FACULTY OF ENGINEERINGDEPARTMENT OF CIVIL ENGINEERING

ECV 3014 CONCRETE AND ENGINEERING GEOLOGY LABORATORYSEMESTER 2 2013/2014LAB TITLE: FLEXURAL TESTDATE OF PRACTICAL: 1ST APRIL 2014GROUP NO: 2No.Matric NumberName

1173555Nur Rabiatul Adawiyah Binti Kamaruddin

2173259Nurfazira Binti Abdul Aziz

3176109Izzat Naim Bin Ibrahim

4175748Abuubakar Abdulkadir Hussein

NAME OF LECTURER: Dr. Azline Mohd NasirNAME OF TECHNICIAN: Mr. Mohd Fairus IsmailNAME OF TEACHING ASSISTANT: Mr.Zain Aliuddin B. Zain Alabidin

DATE OF SUBMISSION: 15thAPRIL 2014

Table of Content

ContentPage

1.0 Introduction

1

2.0 Objectives2

3.0 Procedure

3

4.0 Apparatus and Materials

4

5.0 Results5

6.0 Discussion

7

7.0 Conclusion

7

8.0 References

8

1.0 Introduction

Flexural strength, also known as modulus of rupture, bend strength, or fracture strength, a mechanical parameter for brittle material, is defined as a material's ability to resist deformation under load. The transverse bending test is most frequently employed, in which a specimen having either a circular or rectangular cross-section is bent until fracture or yielding using a three point flexural test technique. The flexural strength represents the highest stress experienced within the material at its moment of rupture. It is measured in terms of stress, sigma. When an object formed of a single material, like a wooden beam or a steel rod, is bent (Fig. 1), it experiences a range of stresses across its depth (Fig. 2). At the edge of the object on the inside of the bend (concave face) the stress will be at its maximum compressive stress value. At the outside of the bend (convex face) the stress will be at its maximum tensile value. These inner and outer edges of the beam or rod are known as the 'extreme fibers'. Most materials fail under tensile stress before they fail under compressive stress, so the maximum tensile stress value that can be sustained before the beam or rod fails is its flexural strength.

Figure 1

Figure 2

2.0 Objectives

In this experiment, the students are able to:

1. Understand the meaning of flexural strength.2. Differentiate between the flexural strength and compressive strength.3. Conduct the flexural test.4. Construct the water cement ratio versus strength graph.

3.0 Procedure

1. The specimen is removed from the curing tank and the excess moisture is wiped from the surface of the specimen. This test is carried out in saturated condition on the scheduled date.2. The specimen is weighed before testing and the nominal dimensions were check and been recorded.3. The bearing surfaces of the supporting and the loading roller is wiped cleans.4. The specimen is placed in the machine. The center with the longitudinal axis of the specimen is corrected at the right angles to the rollers.5. The load is applied at a rate of 0.06 0.04 N/mm.s until the failure occurs.6. The maximum load applied to the specimen is recorded. The flexural strength, is calculated by the equation :

Where, F is the breaking load (N) d1d2 is the lateral dimensions of the cross section (mm) L is the distance between the supporting rollers (mm)

7. The flexural strength is expressed to the nearest 0.1 N/mm

4.0 Apparatus and MaterialsFig 3. Prism mould Hold the fresh concrete to shape it before it hardened.

Fig 4. Weighing balanceTo weigh the prism concrete.

Fig 5. 100mm x 500mm x 100mm concreteAs a material to be tested in this test.

Fig 6. Compressive machine test for prismTo give the flexural force onto the concrete and to obtain the information.

5.0 Results

GroupSpecimen DesignationDimensionWeight (kg)Date of TestingLoad (kN)Flexural Strength (N/mm2)Remark

1Prismatic100mm x 500mm x 100mm11.8271/4/201410.160.185 x 10-2

2Prismatic100mm x 500mm x 100mm11.8861/4/201413.830.252 x 10-2

3Prismatic100mm x 500mm x 100mm11.7741/4/201413.040.237 x 10-2

4Prismatic100mm x 500mm x 100mm11.6081/4/201411.220.2042 x 10-2

Table 1. Results taken from different groups

6.0 Discussion A flexure test produces tensile stress in the convex side of the specimen and compression stress in the concave side. This creates an area of shear stress along the midline. To ensure the primary failure comes from tensile or compression stress the shear stress must be minimized. This is done by controlling the span to depth ratio; the length of the outer span divided by the height of the specimen. For most materials S/d=16 is acceptable. Some materials require S/d=32 to 64 to keep the shear stress low enough. The flexural strength is differed between water/cement ratios. As we can see, group 2 which have 0.55 ratios have a greater strength compare to the other groups. This means that too much water or too less water can affected the strength.7.0 Conclusion In conclusion, we do the experiment to know the ability of concrete to resist an applied bending force such as encountered by concrete pavements or other slabs on ground. A determination of the flexural strength is frequently necessary as part of the design of concrete mixtures to check compliance with established specifications or to provide information necessary to the design of an engineering structure. In the flexural-strength test, a test load is applied to the sides of a test beam. Although the test can be performed upon beams sawed from existing concrete structures, it is more commonly performs upon concrete that are cast for testing purposes. The standard test concrete measures 100mm x 500mm x 100mm. This experiment was conducted in 14 days after moulding to let it age enough.

We are looking forward to know many things about flexure according the lab we have and what we have done as practical we thing as a group it is necessary to know something the student or who ever want to know something about concrete. 8.0 References

1. http://www.ksdot.org/burConsMain/Connections/ConstManual/pdfact5/16_23.pdf2. http://en.wikipedia.org/wiki/Flexural_strength3. http://www.nrmca.org/aboutconcrete/cips/16p.pdf