Investigation of compressive strength of concrete made by different types of aggregate in marine environment in bangladesh

PRESIDENCY UNIVERSITY

Azimur Rahman School of Engineering

Department of Civil Engineering

Thesis

CE- 494 & 495

“Investigation of Compressive Strength of Concrete Made by

Different Types of Aggregate in Bangladesh in Marine

Environment”

As Partial Fulfillment for Degree of B.Sc. in Civil

Engineering

This Thesis is Prepared By

Supervised By

Prof. Dr. Engr. Zahid Hossain Prodhan

Professor

Department of Civil Engineering

Presidency University, Bangladesh

121 033 045

121 035 045

121 037 045

121 120 045

Md. Jasim Uddin

Md. Nazmul Hasan

Md. Moinur Rahman Abir

Saifullah

Acknowledgement

We would like to express our special thanks of gratitude to our cordial teacher

Prof. Dr. Engr. Zahid Hossain Prodhan who gave us the golden opportunity to do

this wonderful project on the topic “Investigation of Compressive Strength of

Concrete Made by Different Types of Aggregate in Bangladesh in Marine

Environment” which also helped us in doing a lot of research and we came to

know about so many new things we are really thankful to him.

Secondly, we would also like to thank the Department of Civil Engineering, PU

for helping us a lot in finalizing this project within the limited time frame.

Authors

Presidency University, 2016

Abstract

In this thesis project, we created 15 cylinders of concrete using different coarse aggregate We

collect five areas coarse aggregate. Jaflong stone, Bholaganj stone, Dinajpur stone, Mymensingh stone and L.C black stone. The effect of fineness modulus of both fine and coarse aggregates maximum size of coarse aggregate on the compressive strength of concrete was studied in the research work. Water cement ratio, the aggregate-cement ratio was kept constant. Only 28 days’ compressive strength was measured to evaluate the result. A mixture of Sylhet sand was used as fine aggregate and stone chips were used as coarse aggregate We used 4 in. x 8 in. cylinders. We make 5 set cylinder stone chips were used as coarse aggregate. Five set (1:2:4) ratio for five sets of cylinders was crushed in this study with a different combination of coarse aggregate grading for each cylinder.

Concrete structures have been designed on the basis of strength criteria. The compressive strength of concrete is traditionally determined by testing 28 days cured cylinder test and this

strength is used in designing concrete structures.

The goal of this study was to investigate the effect of coarse aggregate on the compressive strength of concrete. Hence, to observe the viability of the use of coarse aggregate in concrete, the method of curing was also investigated to understand its effect on the maximum compressive strength.

All the test result values of coarse aggregates have been compared with standard values of ACI, BS, AASHTO, IS and PWD.

Table of Contents Chapter 01: Introduction ..............................................................................................................1

1.1 General .............................................................................................................................................. 1

1.2 Background ....................................................................................................................................... 1

1.3 Objectives ......................................................................................................................................... 2

1.4 Scope of Study ................................................................................................................................. 2

1.5 Flow Chart ........................................................................................................................................ 3

Chapter 02: Literature Review ....................................................................................................4

2.1 General .............................................................................................................................................. 4

2.2 Compressive Strength ..................................................................................................................... 5

2.3 Concrete ............................................................................................................................................ 5

2.4 Aggregate .......................................................................................................................................... 6

2.4.1 Fine Aggregate .............................................................................................................................. 6

2.4.2 Coarse Aggregate ......................................................................................................................... 7

2.4.3 Shape of Aggregate ...................................................................................................................... 7

2.4.3.1 Rounded Aggregate ................................................................................................................... 7

2.4.3.2 Irregular or Partly Rounded Aggregate .................................................................................. 7

2.4.3.3 Angular Aggregate .................................................................................................................... 7

2.4.3.4 Flaky Aggregate ........................................................................................................................ 7

2.4.3.5 Elongated Aggregate ................................................................................................................. 7

2.4.3.6 Flaky & Elongated Aggregate ................................................................................................. 7

2.4.4 Effect of Aggregate Characteristics ........................................................................................... 7

2.5 Grading of Aggregate ...................................................................................................................... 8

2.5.1 Fine Aggregate Grading .............................................................................................................. 9

2.5.2 Coarse Aggregate Grading ........................................................................................................ 10

2.6 Cement ............................................................................................................................................ 10

2.7 Water ............................................................................................................................................... 11

2.8 Modulus of Elasticity .................................................................................................................... 12

2.9 Drying Shrinkage ........................................................................................................................... 13

2.10 Compaction ................................................................................................................................... 14

2.11 Influence of Aggregate / Cement Ration On Strength of Concrete ...................................... 14

2.12 Influence of Water / Cement Ratio on Strength ...................................................................... 14

2.13 Factors Influencing the Strength of Portland Cement Concrete ............................................ 15

Chapter 03: Methodology ...........................................................................................................19

3.1 Introduction..................................................................................................................................... 19

3.2 Properties of Constituent Materials ............................................................................................. 19

3.3 Cement ............................................................................................................................................ 19

3.4 Coarse Aggregate ........................................................................................................................... 19

3.5 Preparation of Concrete Cylinders .............................................................................................. 20

3.6 Casting of Concrete Cylinders ..................................................................................................... 21

3.7 Curing .............................................................................................................................................. 22

3.8 Drying of Concrete Cylinders ...................................................................................................... 22

3.9 Testing Compressive Strength ..................................................................................................... 23

Chapter 04: Laboratory Investigation ......................................................................................24

4.1 Introduction..................................................................................................................................... 24

4.2 Procedure to Determine Particle Size Distribution of Aggregates .......................................... 24

4.3 Sieve Analysis ................................................................................................................................ 24

4.3.1 Sieve Analysis (Course Aggregate) ......................................................................................... 24

4.3.2 Sieve Analysis (Fine Aggregate) .............................................................................................. 26

4.4 Aggregate Impact Value ............................................................................................................... 27

4.4.1 AIV = Aggregate Impact Value (Bholaganj) .......................................................................... 27

4.4.2 AIV = Aggregate Impact Value (LC Black) ........................................................................... 27

4.4.3 AIV = Aggregate Impact Value (Jaflong) ............................................................................... 28

4.4.4 AIV = Aggregate Impact Value (Mymensingh) ..................................................................... 28

4.4.5 AIV = Aggregate Impact Value (Dinajpur) ............................................................................ 29

4.5 Specific Gravity & Absorption Capacity of Coarse Aggregate ............................................... 29

4.5.1 Specific Gravity & Absorption Capacity of Coarse Aggregate (Bholaganj) ...................... 29

4.5.2 Specific Gravity & Absorption Capacity of Coarse Aggregate (L.C Black)...................... 30

4.5.3 Specific Gravity & Absorption Capacity of Coarse Aggregate (Mymensingh) ................ 30

4.5.4 Specific Gravity & Absorption Capacity of Coarse Aggregate (Dinajpur) ........................ 31

4.5.5 Specific Gravity & Absorption Capacity of Coarse Aggregate (Jaflong) ........................... 31

4.6 Unit Weight of Coarse Aggregate ............................................................................................... 32

4.6.1 Unit Weight of Coarse Aggregate (Bholagonj) ...................................................................... 32

4.6.2 Unit Weight of Coarse Aggregate (LC Black) ....................................................................... 32

4.6.3 Unit Weight of Coarse Aggregate (Jaflong) ........................................................................... 33

4.6.4 Unit Weight of Coarse Aggregate (Mymensingh) ................................................................. 33

4.6.5 Unit Weight of Coarse Aggregate (Dinajpur) ......................................................................... 34

4.7 Specific Gravity & Absorption Capacity of Fine Aggregate (Sylhet Sand) .......................... 34

4.8 Unit Weight of Fine Aggregate (Sylhet Sand) ........................................................................... 35

4.9 Compressive Strength of Concrete Test Result ......................................................................... 36

Chapter 05: Result ......................................................................................................................37

5.1 Introduction..................................................................................................................................... 37

5.2 Results ............................................................................................................................................. 37

Chapter 06: Conclusions & Recommendations .......................................................................44

6.1 Introduction..................................................................................................................................... 44

6.2 Limitations ...................................................................................................................................... 44

6.3 Conclusions .................................................................................................................................... 44

6.4 Recommendations .......................................................................................................................... 45

References ............................................................................................................................................. 46

List of Tables

Table 2.1: BS and ASTM Grading Requirements for Fine Aggregate ........................................... 9

Table 5.1 Result of Fineness Modulus of Coarse Aggregates ........................................................ 37

Table 5.2 Result of Apparent Specific Gravity & Absorption Capacity of Coarse Aggregates 38

Table 5.3 Result of SSD & OD of Coarse Aggregates .................................................................... 39

Table 5.4 Result of Aggregate Impact Value of Coarse Aggregates ............................................. 40

Table 5.5 Result of Unit Weight & % Void of Coarse Aggregates ............................................... 41

Table 5.6 Result of Compressive Strength of Concrete for Different Types Coarse Aggregates

................................................................................................................................................................. 42

Introduction Chapter 01

Chapter One

Introduction

1.1 GeneralConcrete is one of the major building materials use in modern day construction. It is a composite construction material composed of cement and other cementitious materials such as fly ash and slag cement, aggregate (generally a coarse aggregate made of gravels or crushed rocks such as limestone, or granite, plus a fine aggregate such as sand), water, and chemical admixtures [1,2]. Concrete is used for numerous purposes in construction such as the construction of buildings, dams, foundations, highways, parking structures, pipes, poles among others [3], Also, the use of

concrete offshore drilling platforms and oil storage tanks is already on the increase. Concrete piers, decks, break-water, and retaining walls are widely used in the construction of harbors and docks. Floating offshore platforms made of concrete are also being considered for the location of airports, power plants, and waste disposal facilities in order to relieve land from pressures of urban congestion and pollution [4], Seawater is water gotten from the sea, which is salty in taste. Sea water can be said to have a solution containing a great number of elements in different proportions. Primarily sea water contains some chemical constituent such ions of chloride, magnesium, calcium and potassium [1,4]. Most seawater is fairly uniform in chemical composition, which is characterized by the presence of about 3.5 percent soluble salts by weight. The ionic concentrations of Na+ and Cl- are the highest, in the Atlantic Ocean typically 11000 and 20000mg/Liter respectively.

The primary chemical constituents of seawater are the ions of chloride, sodium, magnesium, calcium and potassium [1]. The concentration of major salt constituent of seawater is given in percentage such as 78% NaCl, 10.5% MgCl2, 5% MgSO4, 3.9% SO4, 2.3% K2SO4 and 0.3% KBr

[3]. It is evident from above that sodium chloride is by far the predominant salt component of seawater. NaCl and MgCl2 are a total 88.5% of the entire salt content [4].

1.2 BackgroundEarly prediction of concrete compressive strength enables to know quickly about the concrete

and its probable weakness and decide to continue the construction or manage the destruction program. Therefore, prediction of the compressive strength of concrete has been an active area of research. Several methods for early estimation have been introduced in some previously published studies. These attempts were made to predict the 2X day's concrete compressive

strength from early days’ test results but those had some limitations Many efforts are made on using different techniques as computational modeling, statistical techniques. A number of research efforts have concentrated on using a multivariable regression model to improve the accuracy of prediction. In a recent study multivariable power equation is chosen as an effective model for prediction of the strength of different ages of concrete.

In the above equation compressive strength of a particular day variables Age which is considered

as the dependent variable on the has significant correlation with the strength of the water-cement ratio (W/C), cement (C), water (W), sand (FA), Aggregate (CA) content and density of concrete

(𝜌) and then the becomes it is expected that the strength gains pattern of stone aggregate concrete

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would be quite similar to that of stone aggregate concrete, the effectiveness of the proposed

mathematical model for strength prediction is also tested with these stone aggregate concrete test

results. Determined predict the strength of concrete for a particular age directly. To know about

the strength history of the corresponding day it is required individually. Some recent studies

considered the early day’s strength result as an important index for the prediction of concrete

strength and the aim of this study is also to predict the concrete compressive strength from early

days’ strength result. Previously many parameters have been considered for prediction of

concrete strength which influences its strength gaining characteristics. In this study, an attempt is

made to predict the concrete strength from an early day’s concrete strength test result. The model

is developed by exploring the concrete strength gain pattern with age.

1.3 Objectives The objectives of the Study are following:

Comparison of compressive strength of Concrete by using various types of coarse

aggregates in different zone of Bangladesh.

Spatial variation of physical characteristics of coarse aggregates in Bangladesh.

Microstructural characteristics of coarse aggregate in Bangladesh.

1.4 Scope of The Study Chapter 2 will provide a literature review of published material that is relevant to this project.

The portion of Chapter 2 that reviews the factors that affect the compressive strength of concrete

will serve as a general information source concerning the basic properties associated with

concrete strength. The factors affecting the correlation between the strengths of 4 in. x 8 in.

cylinders will be reviewed next. The variability of normal and high-strength concrete will be

discussed as well as changes made to design codes based on the variability of high-strength

concrete. Chapter 4 is a summary the logic used in determining the laboratory testing program

based on the conclusions from the literature review and the available materials and equipment.

Information given in this chapter will consist of concrete mixture proportions and material

properties. Chapter 3 provides the methods and equipment used to carry out the laboratory

testing program. Fresh and hardened concrete test procedures will be explained along with their

accompanying ASTM standards. Chapter 5 is a presentation of the results of the laboratory

testing program in text and graphical form. Fresh concrete properties will be given for each batch

of concrete. The ratio of 4 x 8 in. cylinder strengths and the variability of the results will be

analyzed through graphical representations and statistical analysis. The results of the laboratory

testing program will be compared to the conclusions of the literature review. Chapter 6 is a

discussion of several suggested ways that 4 x 8 in. cylinders could practically be implemented

for quality assurance testing. Recommendations will then be made based on the conclusions of

the literature review, the results of the test data, and previously suggested implementations

procedures. Chapter 4 is a presentation of the comparisons between the literature review

conclusions and the test results. It will also present the recommendations given in Chapter 3.

Appendix A will give, in tabular form, individual test results for all cylinders.

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1.5 Flow Chart

Material Collection

Zaflong Mymensingh Dinajpur LC (Black) Bholagonj

Sieve Analysis Aggregate Impact Value (AIV)

Specific Gravity & Absorption Capacity Test (CA)

Specific Gravity & Absorption Capacity Test (FA)

Result Compressive Strength Test

Cylinder Casting & Curing in Salt Water

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Literature Review Chapter 02

Chapter Two

Literature Review

2.1 General A literature review of the effect of coarse aggregate grading compressive strength on the

performance of portland cement concrete, use of Sylhet sand some proportioning methods is

presented in this chapter.

Since concrete is a large hardened mass of heterogeneous its properties are flanked by a large

number of variables related to difference types and amounts of ingredients, the difference in

mixing, transporting, placing and curing and the difference in specimen fabrication and test

details. Because of the many variables, methods of checking the quality of concrete must be

employed. The usual procedure is to cast strength of the concrete in the structure. The reliability

of this assumption should always be questioned because of different curing condition for the

specimen and the structure, because poor workmanship in placing in the structure may not be

reflected in tests of specimens and because poor testing procedures may provide false results. A

pattern of tests should be used rather than placing reliance only a few tests to cheek uniformity

and other characteristics of concrete. Statistical methods as given in ACI standard 214 should be

used where large quantities concrete are involved.

Most concrete is proportioned for a given compressive strength at a given age and consequently,

a compressive test is most frequently used. A 4 x 8 in the cylinder is most commonly required

but the large cylinder is frequently used with mass concrete to be placed dams. Compressive

strength may also be determined from modified cube tests made on beam specimens remaining

after flexural tests and on cores of various size cut from hardened concrete. The details of all

strength tests are given in ASTM standards.

2.2 Compressive Strength The common design compressive strengths required by the construction industry for cast-in-

place, precast and pre-stressed structures range from 3000 to 8000 psi. These design strengths

are economically met with the use of lightweight aggregate. Some lightweight aggregate

concretes can obtain strengths above 8000 psi; however, not all lightweight aggregates are

capable of obtaining these strengths.

A common concept used to indicate the maximum compressive and/or splitting tensile strengths

of concretes using lightweight aggregate is a “strength ceiling.” A mixture reaches its strength

ceiling when using the same aggregate, it possesses only slightly higher strength with higher

cement content. This property is predominantly influenced by the coarse aggregate fraction of

the mixture. The strength ceiling can be increased by reducing the maximum size of the coarse

aggregate.

As with normal weight concrete, water reducing and mineral admixtures can be used with

lightweight concrete to improve the workability, placing, and finishing.

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Kahn (2004) investigated the development of 8,000 psi, 10,000 psi, and 12,000 psi compressive

strengths for high-performance lightweight concretes for precast, prestressed bridge girders. A

strength ceiling of about 11,600 psi was found using a ½-in. expanded slate aggregate and

normal weight natural sand. Laboratory and field mixtures were developed that met the 8,000

psi and 10,000 psi design strength, with the field mixtures attaining higher strengths. Ozyildirim

(2005) investigated 8,000 psi and 4,000 psi design strengths for lightweight concretes used for

beams and decks, respectively. Test beams were prepared and tested for material properties. A

test mixture was designed for normal weight and lightweight high-performance concretes. The

average 28-day compressive strength of the normal weight mixture was close to the 8,000-psi

design strength; however, the average 28-day compressive strength of the lightweight mixture

was below the 8,000-psi design strength. After 1 year, the average compressive strength for the

normal weight mixture was above the 8,000-psi design strength, and the average compressive

strength for the lightweight mixture was still below the design strength. The low compressive

strength was attributed to excess water in the mixture.

Testing was also performed on the actual mixtures used for the bridge beams and deck. For the

bridge beams, the average 28-day compressive strength was at or near the target value of 8,000

psi. The average 28-day compressive strength of the deck was above the specified 4,000 psi

design strength. From these results, the importance of water control in mixture production is

apparent. Therefore, it was determined that better water control was needed during mixture

production.

2.3 Concrete Concrete is the only major building material that can be delivered to the job site in a plastic state.

This unique quality makes concrete desirable as a building material because it can be molded to

virtually any form or shape. Concrete provides a wide latitude in surface textures and colors and

can be used to construct a wide variety of structures, such as highways and streets, bridges,

dams, large buildings, airport runways, irrigation structures, breakwaters, piers and docks,

sidewalks, silos and farm buildings, homes, and even barges and ships. The two major

components of concrete are a cement paste and inert materials. The cement paste consists of

Portland cement, water, and some air either in the loam of naturally entrapped air voids or

minute intentionally entrained air bubbles. The inert materials are usually composed of fine

aggregate, which is a material such as sand, and coarse aggregate, which is a material such as

gravel, crushed stone, or slag. When Portland cement is mixed with water, the compounds of the

cement react to form a cementing medium. In properly mixed concrete, each particle of sand and

coarse aggregate is completely surrounded and coated with this paste, and all spaces between the

particles are filled with it. As the cement paste sets and hardens, it binds the aggregates into a

solid mass. Under normal conditions, concrete grows stronger as it grows older. The chemical

reactions between cement and water that cause the paste to harden and bind the aggregates

together require time. The reactions take place very rapidly at first and then more slowly over a

long period of time.

2.4 Aggregate Since aggregate usually occupies about 75% of the total volume of concrete, its properties have a

definite influence on the behavior of hardened concrete. Not only does the strength of the

aggregate affect the strength of the concrete, its properties also greatly affect durability

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(resistance to deterioration under freeze-thaw cycles). Since aggregately is less expensive than

cement it is logical to try to use the largest percentage feasible. Hence aggregates arc usually

graded by size and a proper mix has specified percentages of both fine and coarse aggregates.

Fine aggregate (sand) is any material passing through a No. 4 sieve. Coarse aggregate (gravel) is

any material of larger size. Fine aggregate provides the fineness and cohesion of concrete. It is

important that fine aggregate should not contain clay or any chemical pollution. Also, fine

aggregate has the role of space filling between coarse aggregates. Coarse aggregate includes: fine

gravel, gravel, and coarse gravel, in fact, coarse aggregate comprises the strongest part of the

concrete. It also has the reverse effect on the concrete fineness. The coarser aggregate, the higher

is the density and the lower is the fineness

2.4.1 Fine Aggregate The term “Sand” is defined as the aggregate with the restriction that it refers to the material

resulting from natural disintegration and abrasion of rock or of completely friable sandstones

(ASTM Designation C 125). Sand is the most common fine aggregate Sand should be free

foreign materials like organic matter, clay etc. The sand grains may be of sharp angular or round.

Sand showing a proper gradation in size from fairly coarse to fairly fine be preferable to either

uniformly coarse or uniformly fine sand. The quality of sand is determined by sieve analysis.

The coarseness or fineness of sand can be identified by fineness modulus the sum (the

cumulative percentage retained in each sieve prescribed by ASTM divided by 100).

2.4.2 Coarse Aggregate The strength of concrete is dependent on size, shape, grading, surface texture mineralogy of the

aggregate, strength, stiffness [5]. Mehta and Monteiro (1993) suggested that the effect of

aggregate strength on the compressive strength of concrete is not considered in the case of

normal-strength concrete, as it is much stronger than the transition zone and cement paste matrix.

Mehta and Monteiro (1993) also explained that the transition zone and the cement paste matrix

would fail before the aggregate and thus nullify the effect of the strength of aggregate. Kosmatka

et al. (2002) also suggested that the aggregate strength is usually not a factor in normal strength

concrete as the failure is generally determined by the cement paste- aggregate bond. Much

research has linked the bonding of the aggregate to the strength of concrete. Neville and Brooks

(1987) explained that greater aggregate surface areas result in better bonding between the

aggregate and the cement paste. They also observed that rough aggregates tend to exhibit better

binding than smooth aggregates. Jones and Kaplan (1957) made similar observations as Neville

and Brooks (1987) but linked the surface properties to the cracking stress suggesting rough

aggregates would crack at a higher stress compared to smooth aggregates, ft. can be seen that

compressive strength decreases with an increase in maximum coarse aggregate size especially

for concretes with low water-cement ratios. It should be noted that the compressive strength is

more sensitive to the water-cement ratio than the maximum aggregate size.

2.4.3 Shape of Aggregate According to ASTM shape the aggregate is classified as:

Rounded aggregate

Irregular or partly rounded aggregate

Angular aggregate

Flaky aggregate

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Elongated aggregate

Flaky and elongated aggregate

2.4.3.1 Rounded Aggregate The aggregate with rounded shape has the minimum percentage of voids ranging from 32 to

33%. It gives a minimum ratio of surface area to given volume and hence requires minimum

water for lubrication. It gives good workability for the given amount of water and hence needs

less cement for a given water cement ratio. The only disadvantages are that the interlocking

between its particles is less and hence the development of bond is poor This is why rounded

aggregate is not suitable for high strength concrete and for pavements subjected to tension.

2.4.3.2 Irregular or Partly Rounded Aggregate The aggregate with irregular shape has a higher percentage of voids ranging from 35 to 37%. It

gives lesser workability than rounded aggregate for the given water content. Water requirement

is higher and hence more cement is needed for constant water cement ratio. The interlocking

between aggregate particles is better than rounded aggregate but not adequate to be used for high

strength concrete and pavements subjected to tension.

2.4.3.3 Angular Aggregate The aggregate with angular shape has the maximum percentage of void ranging from 38 to 45%.

It requires more water for lubrication and hence it gives the least workability for the given water

cement ratio. For constant water cement ratio and workability, the requirement of cement

increase. The interlocking between the aggregate particles is the best and hence the development

of bond is very good. This is why angular aggregate is very suitable for high strength concrete

and for pavements subjected to tension.

2.4.3.4 Flaky Aggregate The aggregate is said to be flaky when its least dimension is less than 3/5th (or 60%) of its mean

dimension. Mean dimension is the average size through which the particles pass and the sieve

size on which these are retained. For example, mean size of the particles passing through 25 mm

sieve and retained on 20 mm sieve is (20+25)/2=22.5 mm. if the least dimension is less than 3/5

x (22.5) = 13.5 mm, then the material is classified as flaky. Flaky aggregate tends to be oriented

in one plane which affects the durability.

2.4.3.5 Elongated Aggregate The aggregate is said to be elongated when its length is greater than 180% of its mean

dimension.

2.4.3.6 Flaky & Elongated Aggregate Aggregate is said to be flaky and elongated when it satisfies both the above condition* Generally

elongated or flaky particles in excess of 10 to 15% are not desirable.

2.4.4 Effect of Aggregate Characteristics Concrete is a mixture of Cementers material, aggregate, and water Aggregate is commonly

considered inert filler, which accounts for 60 to 80 percent of the volume and 70 to 80 percent of

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the weight of concrete. Although aggregate is considered inert filler, it is a necessary component

that defines the concrete’s thermal and elastic properties and dimensional stability. Aggregate is

classified as two different types, coarse and fine Coarse aggregate is usually greater than 4.75

mm, while fine aggregate is less than 4 5 mm the compressive aggregate strength is an important

factor in the selection of aggregate. When determining the strength of normal concrete, most

concrete aggregates are several times normal strength concrete. Lightweight aggregate concrete

may be more influenced by the compressive strength of the aggregates.

Other physical and mineralogical properties of the aggregate must be known before mixing

concrete to obtain a desirable mixture. These properties include shape and texture, sieve

gradation, moisture content, specific gravity, reactivity, soundness and bulk unit weight. These

properties along with the water/concentrations material ratio determine the strength, workability,

and durability of concrete.

The shape and texture of aggregate affect the properties of fresh concrete more than hardened

concrete. Concrete is more workable when the smooth and rounded aggregate is used instead of

rough angular or elongated aggregate. Most natural sands and gravel from riverbeds or seashores

are smooth and rounded and are excellent aggregates. Crushed stone produces much more

angular and elongated aggregates, which have a higher surface-to- volume ratio, better bond

characteristics but require more cement paste to produce a workable mixture.

The surface texture of aggregate can be either smooth or rough. A smooth surface can improve

workability, yet a rougher surface generates a stronger bond between the paste and the aggregate

creating a higher strength [5].

2.5 Grading of Aggregate Grading of aggregate means particle size distribution of the aggregate. If all the particle of an

aggregate were of one size, more voids will be in the aggregate mass. One the other hand an

aggregate having particles of varying size will exhibit smaller voids. The principle of grading is

that the smaller particles fill up the voids left in larger size particles. By adopting proper

percentages, of various size aggregate, composite aggregate mix con is developed which will be

thoroughly Graded. Properly graded aggregate and cement. The grading of aggregate is

expressed in terms of percentages by weight retained on a series of sieves, 75 mm, 20 mm, 4.75

mm coarse are used for grading of coarse aggregate, whereas 10 mm, 4.75 mm, 2.36 mm, 1.18

mm, fine are used for grading of fine aggregate.

Grading determines the workability of the mix, which controls segregation, bleeding water-

cement ratio, handling, placing and other characteristics of the mix. These factors, also affect the

economy, strength, volume change and durability of hardened concrete. The is no universal ideal

grading for the aggregate. However, I S.I. has specified certain limits within a grading must lie to

produce a satisfactory concrete. But these limits depend on upon the shape, surface texture, type

of aggregate and amount of flaky or elongated material variations in the grading of sand, causes

a large variation in workability, strength and other properties. But the variation in the grading of

coarse aggregate does not affect these properties to the extent of fine aggregate.

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2.5.1 Fine Aggregate Grading Over the years, there have been several approaches to specifying the grading requirements for

fine aggregate. First, type grading curves were given as representing ‘good’ grading. The

division into zones was based primarily on the percentage passing the 600 pm (No. 30 ASTM)

Sieve. The main reason for this was that a large number of natural sands divide themselves at just

that size, the grading above and below being approximately uniform. Furthermore, the content of

particles finer than the (No 30 ASTM) sieve has a considerable influence on the workability of

the mix and provides a fairly reliable index of the overall specific surface of the sand. Thus, the

grading zones largely reflected the grading of natural sands available in the United Kingdom.

Little of these sands are now available for concrete making and a much less restrictive approach

to grading is reflected in the requirements. This does not mean that any grading will do rather,

given that grading is one feature of aggregate, a wide range of grading may be acceptable but a

trial-error approach is required. Specifically, requires any fine aggregate to satisfy the overall

grading limits of table 2.1 and also one of the three additional grading limits of the same table,

but one in ten consecutive samples is allowed to fall outside the additional limits. The additional

limits are, in effect, a coarse, a medium, and a fine grading. Other Considerations for Fine

Aggregate.

Very fine sand will increase the water demand of the mix, while very coarse sand could

compromise its workability.

ASTM C33 requires that the sand is less than 45 percent retained on any one sieve. Too much

material on one sieve means gap-grading, which will increase the water demand of the

The amount of material passing the #50 and #100 sieves will affect workability, slab surface

texture, and bleeding. Increased bleeding will occur as the portion passing the #50 sieve

increases. The flatwork finish ability of a mix also increases as the portion passing the #50 sieve

increases.

ASTM C33 limits the amount of material passing the #200 sieve to 3 percent for natural sand

that contains clay. Clay is a very fine particle that greatly increases the water demand of a mix,

reduces strength significantly, and promotes bleeding.

Table - 2.1: BS and ASTM Grading Requirements for Fine Aggregate

Sieve Size Percentage by mass passing sieves ASTM

C33-93 BS 882:1992

BS ASTM

No

Overall Coarse Medium Fine grading grading grading grading

10.0 mm 3/8 in 100 100

5.0 mm 3/16 in 89-100 95-100

2.36 mm 8 60-100 60-100 65-100 80-100 80-100

1.18 mm 16 30-100 30-90 45-100 70-100 50-85

600 mm 30 15-100 15-54 25-80 55-100 25-60

300 mm 50 5-70 5-40 5-48 5-70 10-30

150 mm 100 0-15 2-10

Page 9


For crushed stone, fine aggregate, the permissible limits are increased to 20 percent except for

heavy duty floors.

2.5.2 Coarse Aggregate Grading Coarse in general terms, the ratio of coarse to fine aggregate. When crushed rock, coarse

aggregate is used, a slightly higher proportion of fine aggregate is required than with gravel

aggregate in order to compensate for the lowering of workability by the sharp, angular shape

of the crushed particles.

The requirements of ASTM C 33-93 for the grading of coarse aggregate are reproduced in Table.

The actual grading requirement depends, to some extent, on the shape and surface characteristics

of the particles. For instance, sharp, angular particles with rough surface should have a slightly

finer grading in order to reduce the possibility of interlocking and to compensate for the high

friction between the particles. The actual grading of crushed aggregate is affected primarily by

the type of crushing plant employed. A roll granulator usually produces fewer fines than other

types of crushers, but the grading depends also on the amount of material fed into the crusher.

The larger the maximum size of the coarse aggregate, the lower the water demand of the mix.

For example, a mix containing 1 inch-maximum-size aggregate when both mixes are adjusted to

the same slump. ASTM C33 generally limits the amount of material passing the #200 sieve to 1

percent for natural coarse aggregate containing clay. As stated above, clay is a very fine particle

that greatly increases the water demand of a mix, reduces strength significantly, and promotes

bleeding.

2.6 Cement Construction documents often specify a cement type based on the required performance of the

concrete or the placement conditions. Certain cement manufacturing plants only produce

certain types of Portland cement.

In the most general sense, Portland cement is produced by heating sources of lime, iron, silica,

and alumina to clinker temperature (2,500 to 2,800 degrees Fahrenheit) in a rotating kiln, then

grinding the clinker to a fine powder. The heating that occurs in the kiln transforms the raw

materials into new chemical compounds. Therefore, the chemical composition of the cement is

defined by the mass percentages and composition of the raw sources of lime, iron, silica, and

alumina as well as the temperature and duration of heating. It is this variation in raw materials

source and the plant-specific characteristics, as well as the finishing processes (i.e. grinding and

possible blending of gypsum, limestone, or supplementary cementing materials), that define the

cement produced.

Chemical tests verify the content and composition of cement, while physical testing

demonstrates physical criteria.

In Cl 50/M 85 and C595/M 240, both chemical and physical properties are limited. In L 1157,

the limits are almost entirely physical requirements.

Chemical Jesting includes oxide analyses (SiO2, CaO. Al2O3, Fe2O3. etc.) to allow the cement

phase composition to be calculated. Type II cement are limited in Cl 50/M 85 to a maximum of 8

Page 10


percent by mass of tricalcium aluminate (a cement phase, often abbreviated CTA). Certain

oxides are also themselves limited by specifications: for example, the magnesia (MgO) content

which is limited to 6 percent maximum by weight of Portland cement, because it can impact

soundness at higher levels.

Typical physical requirements for cement are air content, fineness, expansion, strength, heat of

hydration, and setting time. Most of these physical tests are carried out using mortar or paste

created from the cement. This testing confirms that a cement has the ability to perform well in

concrete; however, the performance of concrete in the field is determined by all of the concrete

ingredients, their quantity, as well as the environment, and the handling and placing procedures

user.

Although the process for cement manufacture is relatively similar across North America and

much of the globe, the reference to cement specifications can be different depending on the

jurisdiction. In addition, test methods can vary as well, so that compressive strength requirements

(for example) in Europe don't translate’ directly to those in North America. When ordering

concrete or construction projects, work with a local concrete producer to verify that cement

meeting the requirements of the project environment and application is used, and one that meets

the appropriate cement specification.

2.7 Water Just as water is a source of life for all living things, so it is the primary ingredient for the

beginning of all concrete. Without water or too little water, all that exists is a pile of rocks and

powder. The opposite can also adversely affect the development of concrete. Too much water

and concrete will become a soupy mixture resembling clam chowder rather than a functional

structural material.

Water is imperative for two reasons. One is to hydrate the cement and the second is to create a

workable substance. Hydration of the cement is necessary to form bonds with the aggregate

which in turn give concrete its strength. Conversely, the presence of water-filled spaces within

the concrete is detrimental to its strength. Indications are that concrete strength is directly related

to porosity and the water-cement ratio (W/C). This is shown by the hydration process. As

hydration of cement progress, the volume of solids increases. This volume is in the space

previously occupied by the anhydrite cement. The increase in solids volume indicates a decrease

in porosity.

Porosity affects strength but strength itself is a result of bonding. Developing bonds in mixtures

with high W/C ratios is difficult due to the distances between particles. A high W/C ratio means

a mixture with a high porosity. Therefore, a high porosity means weaker bonds which in turn

lead to lower strength.

The amount of water required to complete hydration and achieve maximum strength has long

been debated. As previously discussed, the strength of concrete is developed through bonds.

These bonds develop through a chemical reaction of cement and water. This reaction produces

calcium silicate hydrate. One gram of cement requires 0.22 grams of water in order to fully

hydrate. However, the volume of the products of hydration is greater than the volume of cement

Page 11


and water used in the reaction. Specifically, it requires a volume of 1.2 mL of water for the

products of hydration for 1mL of cement. This equates to a W/C ratio of 0.42 for complete

hydration (Aitkin and Neville, 2003).

As noted previously, some of the water is required for the workability of the concrete. This

added water is needed because of flocculation that occurs to the particles of cement. This flow

decreases workability and impedes hydration. It is possible to include admixtures which

eliminate flocculation. Water once used to counteract this effect is now used for hydration,

thereby reducing the amount of water needed.

Water and its application in pervious concrete are extremely critical. Since fines are eliminated

from pervious concrete, strength relies on the bond of the cement paste and its interface with the

aggregate. As with conventional concrete, too little water results in no bonding and too much

water will settle the paste at the base of the pavement and clog the pores. The correct amount of

water will maximize the strength without compromising the permeability characteristics of the

pervious concrete.

The concepts of hydration and workability will be considered when creating mixtures of

pervious concrete with varying ratios of cement, aggregate, and water. Water will be added to

various mixtures of aggregate and cement in experiments designed to maximize hydration and

optimize compressive strength. The goal is to determine an appropriate range of W/C ratios that

will yield high compressive strengths in the previous concrete.

2.8 Modulus of Elasticity The modulus of elasticity of a given concrete depends on the relative amounts of aggregate and

paste and their individual module. The modulus of elasticity of normal weight concrete is

typically higher because of the higher modulus of the normal weight aggregate as compared to

that of the lightweight aggregate. Typically, the modulus of elasticity for normal weight

concrete ranges from 3 to 4 x106 psi. Lightweight concretes usually have a modulus of elasticity

of about ½ to ¾ that of a normal weight concrete.

AASHTO addresses the lower modulus of elasticity of lightweight concrete by specifying an

equation which includes a term for the unit weight. This equation should be further investigated

for typical high-performance, high-strength lightweight concretes, because the modulus term is

an extremely important component of prestress loss and deflection calculations.

If the modulus is not accurately predicted, the other calculations will also be in error.

Kahn (2004) obtained the modulus of elasticity values for high-performance lightweight

concretes in the range of 2,980 psi to 4,680 psi. Ozyildirim et al. (2005) obtained the modulus of

elasticity values of about 3,000 psi for high-performance lightweight concrete. Ozyildirim’s

investigation also showed that the modulus of elasticity for the lightweight concretes was, as

expected, lower than the normal weight concrete mixtures. Modulus of elasticity was measured

for the beam and deck mixtures used in the investigation and compared to theoretical equations

used by ACI. The values for the beam mixtures were a close match; however, the measured

values for the deck mixtures were lower than the predicted values of the theoretical equations.

Page 12


Stiffey (2005) conducted an investigation to determine a new equation that more accurately

predicts the modulus of elasticity of lightweight concrete. The current equations specified by

ACI 318 (ACI, 2005) and ACI 363 – Guide for High Strength Concrete have been found to be

inaccurate for lightweight concrete. A percent difference statistical analysis between

Stiffed stated that further research is needed to verify the proposed equations for all types of

lightweight aggregate.

Lightweight aggregates have a significant effect on modulus of elasticity as discussed above.

Modulus of elasticity is vital to accurately predict girder camber, girder deflections, and prestress

losses. The verification or modification of existing EC models for lightweight concrete with

compressive strengths up to 10,000 psi is necessary if high performance, lightweight concrete is

to receive widespread use.

2.9 Drying Shrinkage Drying shrinkage is the reduction in concrete volume due to water loss and is important because

it can affect the extent of cracking, prestress loss and warping in concrete structures. For

normally cured concretes, lightweight concretes exhibit greater drying shrinkage than normal

weight concretes at lower strengths. At higher strengths, the drying shrinkage of lightweight

concretes is similar to that of normal weight concretes. The use of partial replacement of

lightweight sand with normal weight sand has been shown to reduce the drying shrinkage.

Steam curing aids in reducing the drying shrinkage of lightweight concrete by approximately 10

to 40%. The lower ranges of these drying shrinkage values are similar to typical normal weight

concretes.

Vincent (2003) investigated the creep and shrinkage of the lightweight, high strength concrete

used in the Chickahominy River Bridge in Virginia. He tested both standard cure and match-

cured specimens, as well as concrete produced in the lab and concrete produced in a precast

plant. He compared his results with creep and shrinkage results from Meyerson (2001) who had

tested high-performance, high-strength normal weight concrete of similar strength. Vincent

noted that the shrinkage strains of the lightweight concrete were 30% higher than the normal

weight concrete.

Kahn (2004) showed that the 620-day drying shrinkage values for 8,000 psi and 10,000 psi

design strengths were 820 and 610 microstrains, respectively. Ozyildirim et al. (2005) showed

that the one-year drying shrinkage for lightweight concrete ranged from 555 to 615 microstrain,

while the normal weight concrete tested had drying shrinkage of 505 microstrains at one year.

Currently the AASHTO models for creep and shrinkage do not address unit weight; however,

this is an area in which uncertainty remains, and which would benefit from further research.

Researchers have generally found that lightweight concrete experiences more drying shrinkage

than normal weight concrete. This appears to be especially true for high performance,

lightweight concrete. Further study of drying shrinkage of high performance, lightweight

concrete is required so that modifications to existing equations that predict prestress loss due to

drying shrinkage can be made.

Page 13


2.10 Compaction

The amount of compaction can have considerable effects on the function of pervious concrete. A

higher degree of compaction that takes place when the concrete is placed will directly lead to a

higher level of strength in the concrete. This is due to the densification of the concrete and the

elimination of voids. These are the same voids necessary for the permeability of the water. Too

much compaction will, therefore, result in a loss of permeability through the concrete and a

failure of the pervious concrete system.

2.11 Influence of Aggregate / Cement Ratio on Strength of Concrete The richness of the mix affects the strength of all medium and high strength concrete, i.e. those

with the strength of about MPA (500 psi) or more. There is no doubt that aggregate / cement

ratio, is only a secondary’ factor in the strength of concrete but it has been found that for a

constant water/cement ratio a leaner mix leads to higher strength.

The reasons for this behavior are not clear in certain cases, some water may be absorbed by the

aggregate a larger amount of aggregate absorbs a quantity of water. The effective water / cement

ratio being thus reduced in other cases a higher aggregate content ratio would lead to lower

shrinkage and lower bleeding and therefore to less damage to the bond between the aggregate

and the cement paste, the content paste, the thermal change caused by the heat of hydration of

cement would be smaller 6.80. The most likely explanation, however, lies in the fact that the

total water content per cube meter of concrete is lower in a leaner mix than in a rich one. As a

result, in the leaner mix, the voids form a smaller fraction of the total volume of concrete and it

is these voids that have an adverse effect on strength.

Studies on the influence of aggregate content on the strength of concrete with a given quality of

cement paste indicate that when the volume of aggregate (as a percentage of the total volume) is

increased from zero to 20, there is a gradual decrease in compressive strength but between 40

and 80 percent there is an increase 6.40. The reasons for this effect are not clear, but it is the

same at various water cement ratio 6.41. The influence of the volume of aggregate on tensile

strength is broadly similar 6.40.

2.12 Influence of Water / Cement Ratio on Strength of Concrete It is the ratio of water to cement in a concrete mixture. Water and cement both are taken by

volume. Strength and workability of the concrete greatly depend on upon the amount of water.

For a particular proportion of materials, there is a specific amount of water which gives the

optimum strength to the concrete.

It was Mr. Duff abrasive who in 1981 stated that the strength that the strength of the concrete is

dependent only upon w/c ration in a workable concrete mix greater will be its strength.

Letter Mr. Power proved that cement does not combine chemically with more than half

quantity of water in the mix- Cement requires about 1/8th to 1/4th of its own weight of water to

become completely hydrated. This suggests that if a W/C ratio is less than 0.4 to 0.5 complete by

hydration of the cement can be secured.

Page 14


2.13 Factors Influencing the Strength of Portland Cement Concrete The formation, structure and consequences of the transition zone have been the focus of much

research since the mid-1980s. Suggested mechanisms for its formation include an increased

water: cement ratio at the paste aggregate/interface due to:

the ‘wall effect’, whereby the cement grains cannot pack as efficiently next to the

aggregate surface as they can in the bulk paste

mix water separation at the interface due to the relative movement of the aggregate

particles and cement paste during mixing, leading to a higher local water: cement ratio.

a very thin surface layer of calcium silicate hydratefibres on the aggregate, also

containing some small calcium hydroxide (portlandite) crystals

a greater concentration of larger calcium hydroxide crystals and fine needles of calcium

sulphoaluminate (ettringite) than in the bulk paste and hence a greater porosity.

Compressive strength is depending upon some factors like aggregates size & shape etc.

Rough-textured, angular, and elongated particles require more water to produce workable

concrete than smooth, rounded compact aggregate.

Larger sizes of well-graded aggregate and improved grading decrease the void content.

Also, harder aggregate can be selected in highly abrasive conditions to minimize wear.

The void content between particles affects the amount of cement paste required for the

mix.

Angular aggregate increases the void content.

Absorption and surface moisture of aggregate are measured when selecting aggregate

because the internal structure of aggregate is made up of solid material and voids that

may or may not contain water.

The amount of water in the concrete mixture must be adjusted to include the moisture

conditions of the aggregate.

Abrasion and skid resistance of an aggregate are essential when the aggregate is to be

used in concrete constantly subject to abrasion as in heavy-duty floors or pavements.

Different minerals in the aggregate wear and polish at different rates. Harder aggregate

can be selected in highly abrasive conditions to minimize wear.

Page 15


A number of studies have shown the effects of the mixing and curing of seawater on the

compressive strength of cement–sand mortars and corresponding concrete. Research indicates

that seawater is not suitable for the mixing and curing of both plain and reinforced concrete in

marine conditions (Akinkurolere et al. 2007). However, concrete made with the seawater may

have a higher early strength than normal concrete and the reduction in strength with age can be

compensated by reducing the water–cement ratio and that the microstructural examination of

concrete detected chloroaluminate salts in some cracks (Shayan et al. 2010).

Mehta (1980) reported after exposing concrete cylinder to sea water that the section of concrete

that always remain above high-tide lines would be vulnerable to cracking and spalling as shown

by the representation diagram in Figure 1. Another investigation recently carried out by Portland

Cement Association (PCA) on long time study of cement performance in concrete (LTS)

program provides key insights into the performance of concrete in seawater. The results of their

Page 16


37-year study revealed that seawater had no damaging effect on submerged concrete specimens,

regardless of their cementitious composition; whereas, concrete positioned above high tide

suffered more corrosion damage than concrete placed at mean tide levels (Stark, 2001).

Page 17


At 28 days, the rate of strength gain is still increasing in all the concrete cylinders. The fresh

water cylinders also recorded its maximum strength at 28 days. Although, the compressive

strength of the salt water concrete cylinders was slightly higher than that of the freshwater

concrete cylinders.

Page 18

Methodology Chapter 03

Chapter Three

Methodology

3.1 Introduction This chapter includes the experiments required to determine the properties of an ingredient of

concrete. An experimental investigation was carried out on standard size cylinders of 100 mm x

200 mm (4”x8"). The experimental program may be divided into four phases.

The preparation of concrete mix sensing.

The casting of cylinders in the laboratory using Coarse Aggregate and curing for 28-days

as marine environment.

Testing these cylinders to know the crushing strength.

The casting of cylinders in the laboratory using demolish/recycled Coarse Aggregate and

caring for 28-days as before Comprised of the testing result of these cylinders in knowing

the crushing strength.

3.2 Properties of Constituent Materials The concerts mix consisted of ordinary Portland cement, fine aggregate, and coarse aggregate.

Sand was used as fine aggregate and stone chips were used as coarse aggregate.

3.3 Cement OPC 43 grade (JP cement) was used.

3.4 Coarse Aggregate Generally, Bholaganj stone chips, Jaflong stone chips, Dinajpur stone chips, Mymensingh stone

chips, LC black stone chips are aggregate in this study. Study stone chips had been used as a

coarse aggregate as shown in the figure. For the preparation of concrete, 20mm downgraded

crushed stone chips was used as coarse aggregate in case. Coarse aggregates used in this study

were obtained from the crushed cylinders which were cast using coarse aggregate (crushed

stone.) The aggregate most of which are retained on the 4.75mm sieve, the recycled coarse

aggregate was properly washed to remove dust and dried up before using in the preparation of

concrete as shown in the figure.

(a) (b)

Page 19


Sample of CA (a) LC Black (b) Dinajpur (c) Jaflong (d) Bholagonj (e) Mymensingh

3.5 Preparation of Concrete CylindersFive sets of (4”x 8”) cylindered were cast in two successive steps. Then the containing twenty cylinders were cast with those Bholaganj, Jaflong, Mymensingh, Dinajpur, LC black stone chips

(1:2:4) coarse aggregates. Mobil was used as lubricating oil to wipe the inside of the molds for its easy removal after hardening of the concrete. Fresh concrete was prepared as per designed mix in a drum type mixture machine as shown in the figure immediately after unloading from mixture machine, the fresh concrete was placed in the mold in three layers and compacted by using 16mm (5/8”) diameter and 600mm (24”) in length tampering rod with hemispherical tip as shown in the figure. In all cases, the number of tempting was 2.5 per layer proper compaction

was censured over the cross-section of the mold through uniform distribution of the tempting strokes. Then the specimen was stored undisturbed for 24 hours in such a way that it prevents

(c) (d)

(e)

Page 20


moisture loss and maintained the specimen within room temperature. Weight batching is the

correct method of measuring the materials. For important concrete, invariably, weight batching

system is should be adopted. In this study weigh batching, has been used for measuring the

materials.

Cylinder Preparing

3.6 Casting of Concrete Cylinders The casting was done at SM lab of Presidency University, Bangladesh. All stones were cast in

the different cylinder by the proportion of 1:2:4. After casting we merged that cylinder in water

drum for 24 hours.

Page 21


3.7 Curing During this phase, what calls initial curing. the cylinders can stay in this location for up to 24

hours, but must be kept at a temperate between 23/c and in a marine environment gives several

ideas on ways to achieve this marine environment keeping cylinders out of the sun in all cases

curing was done for a period of 28 days. But it was approaching to observe whether it has any

significant impact on the compressive strength of concrete.

3.5% salt was mixed in water as marine environment water. After one day of casting concrete,

the concrete specimen, they removed from the casting cylinders and were kept in the curing

drum. They were kept submerged as long as for 28 days After. that were withdrawn from the

tank and were kept dry in the sun. For the rest of the days prior to the test was performed, they

were covered with jute bags and were watered periodically.

Curing in Salt Water

3.8 Drying of Concrete Cylinders Cylinders were kept submerged as long as for 28 days. After withdrawal from the drum, drying

in the open place for one day.

Page 22


3.9 Testing of Compressive Strength The compressive strength test was performed on the concrete cylinder, tested at the curing age of

28 days using the compression testing machine. The cylinder was placed betn the compressive

plates parallel to the surface and then compressed at a uniform rate (without shock) until failure

occurred. The max load at failure and the compressive strength were read through of the screen

at the top of the machine. The compressive strength was calculated by dividing the maximum

load in Newtons (N) by the average cross-sectional area of the specimen in square millimeter

(mm2). The reported result is the average of even samples. The test was carried out according to

BS 1881: part 3.

Compressive Strength Test

Page 23

Laboratory Investigation Chapter 04

Chapter Four

Laboratory Investigation

4.1 Introduction For a good design. a good concrete is a must It is not very difficult to make a good concrete. The

only necessary thing is to have an idea about (lie physical properties of concrete More than sixty

factors can affect the quality of concrete and for that reason vigorous investigation arc needed.

The design of concrete mix by traditional method requires the properties of concrete materials

e.g. coarse and fine aggregate such as specific gravity, unit weight, fineness modulus etc. Hence

information should be available about the properties of different elements of concrete.

4.2 Procedure to Determine Particle Size Distribution of Aggregates The test sample is dried to a constant weight at a temperature of 110-degree C and

weighed.

The sample is sieved by using a set of IS Sieves.

On completion of sieving, the material on each sieve is weighed.

Cumulative weight passing through each sieve is calculated as a percentage of the total

sample weight.

Fineness modulus is obtained by adding a cumulative percentage of aggregates retained

on each sieve and dividing the sum by 100.

4.3 Sieve Analysis Sieve analysis helps to determine the particle size distribution of the coarse aggregates in this we

use different sieves as standardized by the IS code and then pass aggregates through them and

thus collect different sized particles left over different sieves.

4.3.1 Sieve Analysis (Course Aggregate)

Total Materials = 1500 gm. (Sample: Bholagonj)

Sieve

Number

Sieve

Opening

(mm)

Materials

Retained

(gm)

% Materials

Retained

Cumulative %

Retained

Percent Finer

3/4 19.05 424 28.26 28.26 71.74

3/8 9.5 1071 71.4 99.66 0.34

4 4.75 5 0.43 100 0

100 227.92

Fineness Modulus = 227.92/100 = 2.279

Page 24


Total Materials = 1500 gm. (Sample: Jaflong)

Sieve

Number

Sieve

Opening

(mm)

Materials

Retained

(gm)

% Materials

Retained

Cumulative %

Retained

Percent Finer

3/4 19.05 423 28.2 28.2 71.8

3/8 9.5 981 65.4 93.6 6.4

4 4.75 96 6.4 100 0

100 221.8


Total Materials = 1500 gm. (Sample: LC Black)

Sieve

Number

Sieve

Opening

(mm)

Materials

Retained

(gm)

% Materials

Retained

Cumulative %

Retained

Percent Finer

3/4 19.05 406 27.06 27.06 72.94

3/8 9.5 1087 72.46 99.52 0.48

4 4.75 7 0.48 100 0

100 226.58


Total Materials = 1500 gm. (Sample: Dinajpur)

Sieve

Number

Sieve

Opening

(mm)

Materials

Retained

(gm)

% Materials

Retained

Cumulative %

Retained

Percent Finer

3/4 19.05 32 2.13 2.13 97.87

3/8 9.5 1462 97.46 99.59 0.41

4 4.75 6 0.41 100 0

100 201.72


Page 25


Total Materials = 1500 gm. (Sample: Mymensingh)

Sieve

Number

Sieve

Opening

(mm)

Materials

Retained

(gm)

% Materials

Retained

Cumulative %

Retained

Percent Finer

3/4 19.05 654 43.6 43.6 56.4

3/8 9.5 845 56.33 99.93 0.07

4 4.75 1 0.07 100 0

100 243.53


4.3.2 Sieve Analysis (Fine Aggregate)

Total Materials = 500 gm. (Sample: Sylhet Sand)

Sieve

Number

Sieve

Opening

(mm)

Materials

Retained

(gm)

% Materials

Retained

Cumulative %

Retained

Percent Finer

4 4.75 2 0.4 0.4 99.6

8 2.36 19 3.8 4.2 95.8

16 1.19 110 22 26.2 73.8

30 0.59

175 35 61.2 38.8

50 0.30 155 31 92.2 7.8

100 0.15 32 6.4 98.6 1.4

Pan - 7 1.4 100 0

Total = 282.8


Page 26


4.4.1 AIV = Aggregate Impact Value (Bholaganj)

Weight of mold = 1962 gm

Sample + mold weight = 2545 gm

Sieve (8 No)- 2.36mm Retain 498 gm

Passing = 85 gm

Description Calculation

Weight of Sample (surface dry) "A"

gm

583 gm.

Weight of Materials

Retained on 2.36mm Sieve

498 gm

Weight of Materials Passing

2.36mm Sieve “B" gm

85 gm

AIV = B/A x l00

= 85/583 x 100

14.57%

4.4.2 AIV = Aggregate Impact Value (L.C Black)



Sieve (8 No)- 2.36mm Retain = 597 gm

Passing =121 gm


Weight of Sample (surface dry)

“A”gm

718 gm.

Weight of Materials


597 gm


2.36mm Sieve “B” gm

121 gm

AIV = B/A x 100 = 121/718 x 100 16.86%

Page 27


4.4.3 AIV = Aggregate Impact Value (Jaflong)



Sieve (8 No)- 2.36mm Retain = 503 gm

Passing = 95 gm



“A" gm

598 gm.

Weight of Materials

Retained on 2.36mm Sieve “C gm

503 gm


2.36mm Sieve “B" gm

95 gm

AIV = B/A x l00 = 95/598 x 100 15.89%

4.4.4 AIV = Aggregate Impact Value (Mymensingh)


Sample + mold weight = 2600 gm Sieve (8 No)- 2.36mm

Retain = 540 gm

Passing = 98 gm


Weight of Sample (surface dry) ‘A’

gm

638 gm.

Weight of Materials


540 gm



98 gm

AIV = B/A x l00 = 98/638x100 15.36%

Page 28


4.4.5 AIV = Aggregate Impact Value (Dinajpur)



Sieve (8 No)- 2.36mm

Retain = 562 gm

Passing = 101 gm



“A” gm

663 gm.

Weight of Materials


C gm

562 gm



101 gm

AIV = B/A x 100 = 101/663 x 100 15.24%

4.5.1 Specific Gravity & Absorption Capacity of Coarse Aggregate

(Bholaganj)

Data Sheet:

Wt. of S.S.D Sample in Air,

B(gm)

Wt. of S.S.D Sample in Water.

C (gm)

Wt. of O.D Sample in Air.

A (gm)

3100 2000 2969

Tests Formula Calculation Results

Apparent Specific

Gravity

A/(A-C) 2969/ (2969-2000) 3.06

Bulk Specific Gravity

(S.S.D. basis)

B/(B-C) 3100/ (3100-2000) 2.82


(Oven dry Basis)

A/(B-C) 2969/ (3100-2000) 2.70

Absorption Capacity,

D%

(B-A) * 100/A (3100-2969) * 100/

2969

4.43%

Page 29


4.5.2 Specific Gravity & Absorption Capacity of Coarse Aggregate (L.C

Black)

Data Sheet:


B (gm)

Wt. of S.S.D Sample in Water,

C (gm)

Wt. of O.D Sample in Air,

A (gm)

3100 1957 2966


Apparent Specific

Gravity

A/(A-C) 2966/ (2966-1957) 2.94


(S.S.D. basis)

B/(B-C) 3100/ (3100-1957) 2.71


(Oven dry Basis)

A/(B-C) 2966/ (3100-1957) 2.57


D%

(B-A) * 100/A (3100-2966) * 100/

2966

4.52%

4.5.3 Specific Gravity & Absorption Capacity of Coarse Aggregate

(Mymensingh)

Data Sheet:


B (gm)


C (gm)


A (gm)

3000 1899 2868


Apparent Specific

Gravity

A/(A-C) 2868 / (2868-1899) 2.96


(S.S.D. basis)

B/(B-C) 3000 / (3000-1899)

2.72


(Oven dry Basis)

A/(B-C) 2868 / (3000-1899) 2.60


D%

(B-A) * 100/A (3000-2868) * 100/

2868

4.60%

Page 30


4.5.4 Specific Gravity & Absorption Capacity of Coarse Aggregate (Dinajpur)

Data Sheet:


B (gm)


C (gm)


A (gm)

3000 1895 2883


Apparent Specific

Gravity

A/(A-C) 2883/ (2883-1895)

.

2.92


(S.S.D. basis)

B/(B-C) 3000/ (3000-1895) 2.71


(Oven dry Basis)

A/(B-C) 2883/ (3000-1895)

2.61


D%

(B-A) * 100/A (3000-2883) * 100/ 2883

4.06%

4.5.5 Specific Gravity & Absorption Capacity of Coarse Aggregate (Jaflong)

Data Sheet:


B (gm)


C (gm)


A (gm)

3000 1855 2895


Apparent Specific

Gravity

A/(A-C) 2895/ (2895-1855) 2.78


(S.S.D. basis)

B/(B-C) 3000/ (3000-1855) 2.62


(Oven dry Basis)

A/(B-C) 2895/ (3000-1855) 2.53


D%

(B-A) * 100/A (3000-2895) * 100/ 2895 3.63%

Page 31


4.6.1 Unit Weight of Coarse Aggregate (Bholagonj)

Data Sheet

Type of

Aggregate

Wt. of

Bucket (lb)

Wt. of

Bucket +

Materials

(lb)

Wt. of

Materials

(lb)

Avg. Wt.

of

Materials

(lb)

Volume of

Bucket

(cft)

Unit

Weight, M

(lb/cft)

Shoveling 3.84 12.63 8.79

Rodding 3.84 13.78 9.94 9.58 0.098 97.75

Shaking 3.84 13.86 10.02

Unit Weight

M

(lb/cft)

Bulk Sp. Gr.

S

(O-D basis)

Density of Water

W

(lb/cft)

% Void

𝑆 𝑥 𝑊 − 𝑀

𝑆 𝑥 𝑊 𝑥 100

97.75 2.7 62.4 41.98%

4.6.2 Unit Weight of Coarse Aggregate (LC Black)

Data Sheet

Type of

Aggregate

Wt. of

Bucket (lb)

Wt. of

Bucket +

Materials

(lb)

Wt. of

Materials

(lb)

Avg. Wt.

of

Materials

(lb)

Volume of

Bucket

(cft)

Unit

Weight, M

(lb/cft)

Shoveling 3.84 12.52 8.68

Rodding 3.84 13.81 9.97 9.90 0.098 101.05

Shaking 3.84 14.90 11.06

Unit Weight

M

(lb/cft)

Bulk Sp. Gr.

S

(O-D basis)

Density of Water

W

(lb/cft)

% Void


𝑆 𝑥 𝑊 𝑥 100

101.05 2.57 62.4 37.48%

Page 32


4.6.3 Unit Weight of Coarse Aggregate (Jaflong)

Data Sheet

Type of

Aggregate

Wt. of

Bucket (lb)

Wt. of

Bucket +

Materials

(lb)

Wt. of

Materials

(lb)

Avg. Wt.

of

Materials

(lb)

Volume of

Bucket

(cft)

Unit

Weight, M

(lb/cft)

Shoveling 3.84 12.44 8.6

Rodding 3.84 13.50 9.66 9.42 0.098 96.12

Shaking 3.84 13.85 10.01

Unit Weight

M

(lb/cft)

Bulk Sp. Gr.

S

(O-D basis)

Density of Water

W

(lb/cft)

% Void


𝑆 𝑥 𝑊 𝑥 100

96.12 2.53 62.4 39.12%

4.6.4 Unit Weight of Coarse Aggregate (Mymensingh)

Data Sheet

Type of

Aggregate

Wt. of

Bucket (lb)

Wt. of

Bucket +

Materials

(lb)

Wt. of

Materials

(lb)

Avg. Wt.

of

Materials

(lb)

Volume of

Bucket

(cft)

Unit

Weight, M

(lb/cft)

Shoveling 3.84 12.90 9.06

Rodding 3.84 14.30 10.46 9.83 0.098 100.31

Shaking 3.84 13.81 9.97

Unit Weight

M

(lb/cft)

Bulk Sp. Gr.

S

(O-D basis)

Density of Water

W

(lb/cft)

% Void


𝑆 𝑥 𝑊 𝑥 100

100.31 2.60 62.4 38.17%

Page 33


4.6.5 Unit Weight of Coarse Aggregate (Dinajpur)

Data Sheet

Type of

Aggregate

Wt. of

Bucket (lb)

Wt. of

Bucket +

Materials

(lb)

Wt. of

Materials

(lb)

Avg. Wt.

of

Materials

(lb)

Volume of

Bucket

(cft)

Unit

Weight, M

(lb/cft)

Shoveling 3.84 12.67 8.83

Rodding 3.84 13.99 10.15 9.89 0.098 100.91

Shaking 3.84 14.53 10.69

Unit Weight

M

(lb/cft)

Bulk Sp. Gr.

S

(O-D basis)

Density of Water

W

(lb/cft)

% Void


𝑆 𝑥 𝑊 𝑥 100

100.91 2.61 62.4 38.04%

4.7 Specific Gravity & Absorption Capacity of Fine Aggregate (Sylhet Sand)

Data Sheet

Wt. of pycnometer filled

with water to calibration

mark. (B gm)

Over Dry

Wt. in Air

(A gm)

Wt. of pycnometer with specimen

and water to calibration mark (C

gm)

Wt. of S.S.D

sample in Air

S gm

1158 gm 487 gm 1463 gm 500 gm


Apparent Specific A 487 2.675

Gravity B+A-C 1158+487-1463

Bulk Specific Gravity A 487 2.497

(Oven Dry Basis) B+S-C 1158+500-1463

Absorption Capacity

D%

S-A 500-487 2.67%

A 487

Bulk Specific Gravity S 500 2.74

(S.S.D. Basis), G B+S-C 1158+487-1463

Page 34


4.8 Unit Weight of Fine Aggregate (Sylhet Sand)

Data Sheet

Type of

Aggregate

Wt. of

Bucket (lb)

Wt. of

Bucket +

Materials

(lb)

Wt. of

Materials

(lb)

Avg. Wt.

of

Materials

(lb)

Volume of

Bucket

(cft)

Unit

Weight, M

(lb/cft)

Shoveling 3.84 13.27 9.43

Rodding 3.84 13.8 9.96 9.86 0.098 100.61

Shaking 3.84 14.04 10.2

Unit Weight, M

(lb/cft)

Bulk Sp. Gr.

S

(O-D basis)

Density of Water

(lb/cft)

% Void


𝑆 𝑥 𝑊 𝑥 100

100.61 2.5 62.4 35.5%

4.9 Compressive Strength of Concrete Test Result

Data Sheet: Fresh Water

Name of

Aggregate

Avg. Dial Reading

(Ton)

Avg. Dial

Reading

(lb.)

Cylinder’s

Surface Area

Πr2

(Sq. inch)

Avg. Concrete’s

Compressive

Strength

(psi)

Bholagonj 20.2 45248 3602.548

LC Black 24 53760 4280.255

3.1416 x 22

Jaflong 23.6 524864 = 12.56 4208.917

Dinajpur 17.4 38976 3103.185

Mymensingh 17 38080 3031.847

Page 35


Data Sheet: Salt Water

Name of

Aggregate

Avg. Dial Reading

(Ton)

Avg. Dial

Reading

(lb.)

Cylinder’s

Surface Area

Πr2

(Sq. inch)

Avg. Concrete’s

Compressive

Strength

(psi)

Bholagonj 22.4 50176 3994.904

LC Black 25.2 56488 4494.268

3.1416 x 22

Jaflong 25 56000 = 12.56 4458.599

Dinajpur 18 40320 3210.191

Mymensingh 18 40320 3210.191

Page 36

Result Chapter 05

Chapter Five

Result

5.1 Introduction Testing of harden concrete plays an important role in controlling and confirming the quality of

cement concrete work. As per. ASTM, standard requirements of the specification. 100 mm x 200

mm (4” x 8") cylinders are tested after curing. Two different sets containing a total number of

fifteen and three cylinders respectively were cast. They were differentiated in terms of the type

of the type of coarse aggregate used. Which are shown in the tables onward Water cement ratio

of 0.68 and mix proportion of 1:2:4 and by selected during the investigation.

5.2 Results The compressive strength test results are explained and explained from one aspect in tabular

forms as well as graphically. The variation of compressive strength with respect to the type of

coarse aggregate used and the method of curing employed are discussed. The total number of

concrete cylinder is divided into two sets based the type of aggregate used and the method of

curing applied is the rest results of compressive strength.

Table & Chart 5.1 Result of Fineness Modulus of Coarse Aggregates

Type of Aggregates FM

Bholagonj 2.279

LC Black 2.266

Jaflong 2.218

Mymensingh 2.435

Dinajpur 2.017

0

0.5

1

1.5

2

2.5

3

Bholagonj LC Black Jaflong Mymensingh Dinajpur

Page 37

Result Chapter 05

Table & Chart 5.2 Result of Apparent Specific Gravity & Absorption Capacity of Coarse

Aggregates

Type of Aggregates Apparent Specific Gravity Absorption Capacity (%)

Bholagonj 3.06 4.43

LC Black 2.94 4.52

Jaflong 2.78 3.63

Mymensingh 2.96 4.60

Dinajpur 2.92 4.06

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5


Apparent Specific Gravity Absorption Capacity (%)

Page 38

Result Chapter 05

Table & Chart 5.3 Result of SSD & OD of Coarse Aggregates

Name SSD (gm) OD (gm)

Bholagonj 2.82 2.70

Jaflong 2.62 2.53


Dinajpur 2.71 2.61

LC Black 2.71 2.57

2.35

2.4

2.45

2.5

2.55

2.6

2.65

2.7

2.75

2.8

2.85

Bholagonj Jaflong Mymensingh Dinajpur LC Black

SSD (gm) OD (gm)

Page 39

Result Chapter 05

Table & Chart 5.4 Result of Aggregate Impact Value of Coarse Aggregates

Name AIV

Bholagonj 14.57

Jaflong 15.89

Mymensingh 15.36

Dinajpur 15.24

LC Black 16.86

13

13.5

14

14.5

15

15.5

16

16.5

17

17.5


Page 40

Result Chapter 05

Table & Chart 5.5 Result of Unit Weight & % Void of Coarse Aggregates

Type of Aggregates Unit Weight (lb/cft) % Void

Bholagonj 97.75 41.98

LC Black 101.05 37.48

Jaflong 96.12 39.12


Dinajpur 100.91 38.04

0

20

40

60

80

100

120


Unit Weight (lb/cft) % Void

Page 41

Result Chapter 05

Table & Chart 5.6 Result of Compressive Strength of Concrete for Different Types Coarse

Aggregates

Name Mix

Properties

W/C Avg. Compressive

Strength (Fresh Water)

(psi)

Avg. Compressive

Strength (Salt Water)

(psi)

Bholagonj 1:2:4 0.5 3602.548 3994.904

Jaflong 1:2:4 0.5 4208.917 4458.599

Mymensingh 1:2:4 0.5 3031.847 3210.191

Dinajpur 1:2:4 0.5 3103.185 3210.191

LC Black 1:2:4 0.5 4280.255 4494.268

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000


Avg. Cmpressive Strength: Fresh Water (psi) Avg. Cmpressive Strength: Salt Water (psi)

Page 42

Result Chapter 05

5.3.1 Failure Pattern of Concrete Cylinder

(a) Cone & Shear (b) Columnar (c) Columnar

(d) Columnar (e) Shear

Cylinders: (a) Bholagonj (b) LC Black (c) Mymensingh (d) Jaflong (e) Dinajpur

Page 43

Conclusions Chapter 06

Chapter Six

Conclusions & Recommendations

6.1 Introduction In this study, five sets of cylinders were fifteen cylinders prepared with Bholaganj. Jaflong, L.C

Black, Dinajpur, Mymensingh stone chips (1:2:4) coarse aggregate.

6.2 Limitations The compressive strength of the concrete depends on upon various factors like water cement

ratio quality of cement, curing period, mix proportion compaction.

6.3 Conclusions The objectives of the study were to find the relation of concrete especially compressive strength

with the both fine and coarse aggregate grading & the maximum size of coarse and combine

finance modules of aggregate. On the basis of this study following conclusion can

be drawn.

To compare the Compressive Strength of Concrete made by different types of aggregate, we got highest in both fresh water & salt water for LC (Black) coarse aggregate and lowest for Mymensingh coarse aggregate. Also, we have found that there was a marginal increase in the of concrete cylinders which were cast and cured with salt water as

compared with the concrete cylinders cast and cured with fresh water. The rate of the

strength gain in fresh water cylinders is slow as compared with the salt water cylinders.

Strengths are also affected by the aggregate type, properties, cement type, age and

curing conditions but with a lower rate than the effect of cement content.

Highest FM: Mymensingh & lowest: Dinajpur.

Highest Absorption Capacity for Mymensingh coarse aggregate and lowest for Jaflong

coarse aggregate.

Got highest Impact Value (AVI) of LC (Black) coarse aggregate and lowest for

Bholaganj coarse aggregate.

Bulk Specific Gravity (S.S.D & O.D Basis) of coarse aggregate; highest for Bholagonj

and lowest was for Jaflong.

Highest Unit Weight: LC (Black) & lowest: Jaflong

From the above finding, we have found that the LC (Black) coarse aggregate was better than the

others coarse aggregate.

Also, we can conclude that there is no reduction in the strength if we use salt water casting and

curing the concrete. There is some increase in the strength if salt water is used for casting and

curing. This concrete can be used for mass concreting without any decrease in strength

properties.

Page 44

Conclusions Chapter 06

6.4 RecommendationsThis is a short scale research work due to the limitation of time and resource. To get the more accurate result large scale research should conduct changing various parameters. Few guidelines were suggested below for future study on this topic.

The use of salt water should be welcomed and not feared for casting and curing of

concrete during construction most especially in the coastal environment.

Water/Cement ratio that will give the minimum value of slump with adequate

workability, as well as minimum cement content, should be used with maximum

aggregate size in order to minimize the shrinkage cracking.

Mix ratio was constant in this study research should be revised for different mix ratio.

With the increases of the aggregate size required water cement ratio lower. So, this study

should be conducted with the different water-cement ratio.

This study should perform for coarse aggregate and it is necessary to prepare standard

grading requirement for both fine and coarse aggregate (stone).

Further study should be made on prevention of reinforcement from sulfate attack in order

to avoid the fear of reinforcement from being easily corroded and on the effect of salt

water on other important characteristics of concrete.

Page 45

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415.

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[14] Regourd, M. L. (1980) “Physio-chemical Studies on Concrete Paste”, New Brunswick, Vol.2, pp.

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[15] Stark, D.C. (2001) “Long-Term Performance of Plain and Reinforced Concrete in Seawater

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Page 46

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