IMPACT OF GEOLOGICAL STRUCTURE ON ALKALI SILICA REACTION · ON ALKALI SILICA REACTION ... opening on the roadway slab ... When Aggregate identified as, there is no method for preventing

THE EFFECT OF

GEOLOGICAL STRUCTURES

ON

ALKALI SILICA REACTION

Presented by

Bhatawdekar Ramesh Murlidhar

M Phil Student, Faculty of Civil Engineering,

Head of Quarry Operation- Holcim Malaysia

Ex Corporate Quarry Advisor- Holcim Indonesia

Supervisor

ASSOC. PROF. DR. EDY TONNIZAM BIN

MOHAMAD

REVIEW

OF

TEST METHODS

FOR

ALKALI AGGREGATE REACTION

BHATAWDEKAR RAMESH MURLIDHAR

.EDY TONNIZAM BIN MOHAMAD

DANIAL ARMAGHANI

Department of Geoteknik and Transportation,

Faculty of Civil Engineering,

University Teknology Malaysia, 1 中国砂石协会

Ramesh Bhatawdekar Mphil Student –Faculty of civil Enginering

Introduction

Stanton (1940) recognized Alkali Silica Reaction (ASR) as durability challenge for concrete.

Various research projects focused on test methods for determining on acceptable criteria last 75

years but none of test methods can exclusively decide acceptable criteria

Field conditions and laboratory conditions may vary which is a major challenge for reliable and

accurate performance tests for the production of durable of concrete for a life time of 50 to 100

years.

Crucial parameters for co-relation of laboratory and field conditions are alkali content, humidity

and temperature

According to Thomas et al., ASR performance test should meet following criteria

Alkali leaching problem to be identified

Assess all (SCM) supplementary Demetrious Materials

Various test methods exist based on standards such as ASTM, British Standards, RILEM which

are followed by many countries

Today’s discussion is on assessment of these test methods which are suitable for early detection

of Alkali Aggregate Reaction so that demand of concrete structures can be met for modern

growing infrastructure

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Alkali Aggregate Reaction

What is Alkali Aggregate Reactivity (AAR)?

AAR causes deleterious expansion of concrete resulting in cracking, spalling loosing

strength of concrete structure at later stage of construction. Some concrete aggregates can

react in alkaline, humid climate, sea water resulting in internal expansion causing deleterious

cracking. Sodium and potassium from cement or external sources like aggregate also take

part in this reaction. Expansion due to AAR is slow process and may be visible deterioration

after 10 to 20 years in tropical climatic conditions.

Two types of AAR

Alkali Carbonate Reaction (ACR)

ACR occur in limestone aggregate having typical mineralogy and microstructure. Sources of

such aggregates is not common. ACR is more aggregation and can be detected in the early

life of concrete structure

Alkali Silica Reaction (ASR)

ASR occur with specific forms of silica (SiO2) minerals and microstructure in aggregates

which reach in alkaline (pH) medium in concrete creating an expansive gel. The gel expands

by absorbing moisture that causes expansion of concrete and subsequent damage. Three

conditions for ASR are Reactive aggregates, Alkalis in cement and moisture.

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Review- Alkali Silica Reaction The alkali–silica reaction (ASR) - highly alkaline cement paste and

reactive non crystalline (amorphous) silica.

Altered aggregate a swelling gel of calcium silicate hydrate (CSH).

Gel exerts an expansive pressure , spilling and loss of strength of the

concrete, finally leading to its failure.

Ca(OH)2 + H4SiO4 → Ca 2+ + H2SiO4 2− + 2 H2O → CaH2SiO4 · 2 H2O

Cracks in Concrete

[HOOVER DAM

USA] Progression and consequence of

the swelling of the ASR gel

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Crack development due to ASR Innocuous because the primary minerals not reactive

(Chow and Abdul Majid Sahat, 1990; Yeap, 1992; Sazali Yaacob et al. 1994).

Reactive secondary minerals such as opal and chalcedony (Quartz) as

infill discontinuities (Yeap, 1992).

Strained quartz and microcrystalline quartz --potentially alkali silica

reactive (Gogte, 1973; Kerrick and Hooton, 1992; Wigum, 1995).

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Why AAR is a concern?

Deleterious to concrete structures

AAR is process is slow and catastrophic failure may not occur if periodic inspection is

carried out and remedial measures are taken

Dimensional stability is important for dams and with AAR the expansion can impact

functioning of structure e.g. flood gates of dam

ASR in concrete pavements can result in concrete pavements and transportation

infrastructure can result in spalling of cracked sections

ASR can accelerate deterioration in concrete structures with other deterioration processes

such as freezing, sulphate attack from soils of concrete foundation, corrosion of reinforced

concrete near sea or river or other water bodies

Moisture variation in tropical climate, additional alkalis from deicing salts, and traffic

loading causing vibration in bridges along with ASR accelerates deleterious impact on

concrete structure.中国砂石协会


ASR Failure in Bridges & Concrete Dam

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ASR in Hirakud Dam, Orissa India

Problems faced due to ASR

Horizontal cracks in the operation gallery,

gates haft, sluice barre

Deflection in the Adit gallery

Buckling of embedded frame of manhole

opening on the roadway slab

Shearing and Snapping of bolts fixing the

guide rails of sluice gates

Horizontal cracks at various levels on the

D/S face of right spillway and vertical

cracks in two blocks and the width of

cracks increasing slowly.

Binding of radial crest gates.

Petrographic Examination &

Electronic Microscope Study

Samples obtained where ASR observed

River shingles/ quartzite pebbles used in

concrete shows occurrence of

cryptocrystalline silica like chert and

chalcedony as well as diorite and granite.

Presence of grano-diorite in crushed rock

aggregate was identified as reactive.

Reactivity mainly to strained quartz having

undulatory extinction

An examination on hardened concrete

revealed that the concrete had adequate

cement content and not attacked by

sulphate, acid waters etc.

Concrete core samples from the right

spillway found to have undergone ASR.

Cracks and voids in the concrete, alteration

of the borders of aggregate.

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Essential Component of ASR

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How AAR can be avoided?

Alkali Carbonate Reactive Aggregate:

When Aggregate identified as, there is no method for preventing ACR. Only alternative is to

have alternative source.

Alkali Silica Reactive Aggregate:

(i)Avoid use of aggregate sources that are determined to be reactive.

(ii) If non reactive aggregates are not available, use low alkali cement with less than 0.6% of Na2Oeq

and total alkali in concrete limited to 3.0 kg / m3 .

(iii) Incorporate Supplementary Cementous Material (SCM) consiting of flyash, natural pozzlana,

slag cement or silica fume

Testing of Aggregates /SCM

.Various test methods exist whether Aggregates are reactive or innocuous

Test methods are used for effectiveness of SCMs on potential ASR中国砂石协会


Types of test methods for ASR

During last various 75 years, various researchers have utilized various test

methods to establish potential alkali silica reactivity of aggregates. None of the

methods can exclusively establish innocuous, potential reactive or reactive

aggregates.

These test methods can be broadly divided into 3 types

Petrographic methods,

Chemical method and

Bar Mortar Methods

There are various test methods which have been experimented and have not

been established yet for consistency of results, comparison with other methods

e.g. Crystallinity Index of quartz with XRD by Bookemans (2004);

Rapid method of alkali silica reactivity of aggregates with a nonlinear resonance

spectroscopy (NIRAS) technique by Chen et al., (2010) and

simple chemical method by Chatarjee and Jensen (1987).

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Summary of Test Methods

.

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Test Methods for determining ACR

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Summary of Test Methods

中国砂石协会


Nonlinear Impact Resonance Acoustic

Spectroscopy (NIRAS)

NIRAS is used to determine alkali silica reactivity of different aggregates.

Bar mortar 25Χ25Χ254 mm is clamped at one end and hammering is done at

central place and free end vibration is measured and resonance frequency is

recorded in a digital oscilloscope.

The resonance frequency are recorded for each sample periodically.

NIRAS is capable of distinguishing ASR damage in bar mortar samples.

NIRAS also provides advantage different levels of reactivity in early stages of

ASR which is significant advantage over conventional testing methods.

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Crystallinity Index of quartz by XRD

Muara and Norman (1976) introduced popular method of crystallinity index of

quartz by X-ray Diffraction (XRD) for susceptibility of aggregates for ASR.

The method involves crushing sample with hammer and grit is pulverized.

Samples are washed with concentrated hydrochloric acid to remove impurities

such as calcite, dolomite or limestone etc.

After washing with distilled water and drying, X-ray difftractograms are

recorded. Difftractograms are made of each sample at different angles and

results are recorded.

Crystallinity Index of quartz may be from 1 to 10.

A straight forward co-relation between CI of quartz with XRD as reported by

Brokemans (2004).中国砂石协会


Simple Chemical Method

A simple chemical method for detection of alkali-silica reactivity of

aggregates was suggested by Chatarjee and Jensen (1987).

The method consists of suspending mixture of CaO and aggregate to be tested

in saturated solution of KCl at 700C for 24 hours. The concentration of OH‾

ion is measured. OH‾ ion concentration is inversely proportional to the

reactivity of the aggregate or sand.

This method developed was in research stage and was not practiced by other

researches.

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Comparison of Test methods

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Factors affecting ASR test results at

laboratory and field Aggregate : Grading in the field Vs excessive crushing, representative sample, Failure to identify

alkali release from aggregates in long term vs short duration of test at laboratory

Temperature : Constant temperature at laboratory Vs temperature variation in the field

Humidity : In tropical climate, due to seasonal rainy season, humidity around concrete sturcture

varies which may not be correlated in laboratory

Comparison of Test Methods

中国砂石协会


Multilaboratory Study of ASTM C1260

The accelerated mortar bar test, developed by the National Building Research Institute (NBRI) in

South Africa, has been adopted in North America for the rapid identification of potentially alkali-

silica reactive aggregates and may also be used for assessing the effectiveness of supplementary

cementing materials. The purpose of the multi-laboratory studies, involving 46 and 32

laboratories, was to obtain data to develop a multi-laboratory precision statement for the test.

In a study involving 46 laboratories, it was found that the multi-laboratory coefficient of variation

after 14 days in solution was 13.3% when the same cement was used and 14.9% when each

laboratory chose a different cement.

In a second study involving 32 laboratories, it was found that the average coefficient of variation

at 14 days in solution was 15.5%.

For mortars giving average expansions after 14 days in solution of greater than 0.1% the multi-

laboratory coefficient of variation (1s% of ASTM C 670) has been found to be 15.2%. Therefore,

the results of two properly conducted tests in different laboratories on specimens of a sample of

aggregate should not differ by more than 43% (d2s% of ASTM C 670) of the mean expansion.中国砂石协会


Test results comparison by researchers

Ghaffori and Islam (2013) reported positive correlation with mineralogy of aggregates and Bar

Mortar Test ASTM C1260 & Prism Mortar Test AXTM C 1293

Jesen , Sintef (2000) compared petrographic methods for potential ASR of aggregates.

ASTM C 295 and BS 812 Part 104 specify grain counting while RILEM AAR 1 compares both

grain counting and point counting.

Raja et al (2014) suggest aggregate tested with presence of reactive with petrographic

examination ASTM C 295 to have further screening with ASTM C 1260 and chemical method

and for effectiveness of SCM ASTM C1567 to be adopted at preliminary stage of project.

Hack ( 2001) verified predictability of ASR Test methods and concluded that there is litle

evidence developed from chemical test ASTM C 289, Mortar Bar Test ASTM C227 AND

Petrographic Analysis ASTM C295.The effect of grading affected mortar bar expansion test

results in consistent. Prism test was suggested in place of mortar bar test.

The concrete prism test (CPT) ASTM C 1293, RILEM AAR-3 is recognized as most reliable for

evaluation of ASR and ACR, Mississauga, (2000); Philadelphia, (2002); Struct (2000). Hooton

(1995) evaluated different test procedures for ASR and concludes that lack of reliability of

traditional test ASTM C 227 or C 289 resulted in development of ASTM C 1260 ABMM and

Canadian concrete prism test (CSA A 23.2- 14A- M94) or ASTM 1105. He further suggested that

in case ASTM C 1260 suggests potentially deleterious, further CPT should be carried out.

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Many researches have reported lack of reliability with chemical method ASTM C 289 and lacks

reliability for confirming reactivity of aggregates (Grattan-Bellew, 1983; Shyan et al, 1988;

Sorrenntio, et al, 1988).

As per ASTM 1987a it has been reported that for reactive rocks containing carbonates such as

dolomite and calcite or silicious magnesium Chemical method ASTM C 289 is not suitable.

Slowly reactive aggregates may not be detected as potential reactive by the chemical method

ASTM C 289 as the amount of reactive material is low or the amount of dissolved silica is

underestimated due to precipitation of certain elements in the constituents of material Shyan ,

(1991).

Shayan (2007) has reported that for 5 slowly reactive Australian aggregates which has damaged

extensive damage to concrete structures were classified as non-reactive or uncertain by

ASTM C 1260. He suggested that the Australian acceptance limit of < 0.1% expansion at 21 days

or that the currently applied 14-day expansion limit be lowered from 0.10% to 0.08% for ASTM

C 1260. However, the AMBT test has to be conducted with other methods or there may be other

reason like high alkali cement used in construction or alkali contribution from aggregates or

external source need to be investigated.

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In a study by Thomas, et.al, (2006) on different test methods for controlling ASR in concrete,

ASTM C 1260 is appropriate rapid method for measuring potential reactive aggregates and can be

compared with other methods like field test, concrete prism test ASTM C 1293 and Mortar bar

ASTM C 227.

Petrographic examination of volcanic rocks at Anderson quarry showed microcytalline to

cryptocrystalline quartz and strained quartz showing potential reactive minerals and the same was

confirmed through ASTM C 1260. Chemical method ASTM C 289 could not identify reactivity

of samples. Volcanic tuffs in Pengarang area of Johor showed strained quartz, crypto to

microcrystalline quartz and fine quartz grains showing undulose extinction ( Chow and Sahat ,

1990; Yacoob et al., 1994)

中国砂石协会


Researchers Views on ACR Vs ACR

The widely used screening test for alkali-silica reactivity ACR , the Accelerated Mortar Bar

Method AMBT , e.g., ASTM Standard C1260, CSA A 23.2-25A, RILEM AAR-02 , is not

appropriate for the evaluation of the expansively of alkali-carbonate reaction aggregates.

In order to reliably screen carbonate aggregates, an accelerated concrete microbar method was

developed in recent years in China. The concrete microbar method was quite similar to the

AMBT, with the main difference being that a relatively coarse single-sized aggregate, 5 -10 mm,

and short fat bars, 40 mm by 40 mm by 160 mm, are used for the new method.

Expansion of 0.1 % at 28 days in the concrete microbar test seems to be reasonable criteria for

screening the alkali-carbonate reactive aggregate based on the concrete prism test results. Alkali-

carbonate reactive aggregates would normally induce limited expansion in the accelerated mortar

bar method e.g., ASTM Standard C 1260, CSA A23.2-25A or RILEM AAR-02 .

Carbonate aggregates inducing high expansions i.e., higher than the proposed limits for the tests

in both the concrete microbar and the accelerated mortar bar tests could possibly be susceptible to

combined alkali-silica and alkali-carbonate reactions.

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An multi-laboratory study on

Accelerated Concrete Microbar Test

As part of an multi-laboratory study on accelerated concrete microbar test for alkali-carbonate

reaction, the effect of a number of variables on expansion were evaluated, including the effect of

alkali content of the cement, the type and source of alkali, the aggregate particle size, and the bar

size.

The addition of alkali in the microbar matrix resulted in reduced ultimate 28-day expansion.

For the two particle sizes and bar sizes tested in this study, particle size 4 - 8 mm and long bars

led to a slight higher expansion than 5- 10 mm particles and short bars at 28 days. Generally, the

bar sizes and particles sizes investigated had no significant influence on concrete microbar

expansion.

The different effect of fly ash on the expansion of bars made with ASR and ACR aggregates

reported in literature was observed in the microbar test. The use of a sufficient amount 25 to 30 %

of a low/moderate calcium or ASTM Class F and low-alkali fly ash in the concrete microbar

method appears to offer a simple test to differentiate the type of aggregate reactivity中国砂石协会


Conclusion

During last 75 various test methods have been developed to establish ASR/ACR.

Exclusive of any test method is not suitable for identifying potential ASR hence more

than 2 or more tests are practiced by researchers.

Petrographic Examination ASTM C 295 is equivalent to RILEM AAR 1 is good method

to find minerals which contribute to potential reactivity.

Bar Mortar Test is most accepted test to establish potential ASR in aggregate as mortar

bar represents concrete and can be correlated with concrete structure in the field.

Accelerated Bar Mortar Test ASTM C 1260 is equivalent to RILEM AAR 2 and practiced

by many researchers to establish potential ASR. ASTM C1260 is also useful for finding

out effectiveness of SCM.

Researchers have found inconsistent results with Chemical Method ASTM C 289.

Chinese Micro Bar Test Method is good method to identify ACR in aggregates.

There are various test methods like simple chemical method, NIRAS, XRD etc for

which further research is required

Use of Information Technology for advanced testing techniques need to be established

for identifying potential ACR/ASR in the field with laboratory testing.

中国砂石协会


Points for discussion-Future challenges in AAR Test development

Chinese Microbar Test is developed for evaluating Alkali Carbonate Reaction.

Whether the similar test can be utilized

With the revolution in Information Technology, how test methods can be

improved to evaluate ASR/ACR/AAR in following aspects: ASR as chemical reaction

ASR as thermodynamic reaction

Image analysis of ASR gel

Computerized model for correlating field condition and laboratory test as field

condition vary as compared to laboratory level中国砂石协会


.

.

中国砂石协会


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中国砂石协会

http://www.nrmca.org/aboutconcrete/cips/43pr.pdf


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IMPACT OF GEOLOGICAL STRUCTURE ON ALKALI SILICA REACTION · ON ALKALI SILICA REACTION ... opening on the roadway slab ... When Aggregate identified as, there is no method for preventing