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CONCRETE TECHNOLOGY

by Jntu Heroes
Type: PracticalInstitute: Jawaharlal nehru technological university anantapur college of engineering Offline Downloads: 10Views: 268Uploaded: 10 months agoAdd to Favourite

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MANUAL FOR CONCRETE TECHNOLOGY LABORATORY IV YEAR I SEMESTER UNDERGRADUATE COURSE IN CIVIL ENGINEERING
CONCRETE LABORATORY EXPERIMENTS 1. FINENESS OF CEMENT 2. NORMAL CONSISTENCY OF CEMENT 3. INITIAL AND FINAL SETTING TIMES OF CEMENT 4. SPECIFIC GRAVITY OF CEMENT 5. COMPRESSIVE STRENGTH OF CEMENT 6. SOUNDNESS OF CEMENT 7. FINENESS MODULUS OF FINE AND COARSE AGGREGATE 8. SPECIFIC GRAVITY, VOID RATIO, POROSITY AND BULK DENSITY OF COARSE AND FINE AGGREGATES 9. BULKING OF SAND 10. WORKABILITY TESTS ON FRESH CONCRETE 11. COMPACTION FACTOR TEST 12. TEST FOR COMPRESSIVE STRENGTH OF CEMENT CONCRETE .
FINENESS OF CEMENT (IS: 269-1989 and IS: 4031-1988) AIM: To determine the fineness of the given sample of cement by sieving. APPARATUS: IS-90 micron sieve conforming to IS:460-1965, standard balance, weights, brush. INTRODUCTION: The fineness of cement has an important bearing on the rate of hydration and hence on the rate of gain of strength and also on the rate of evolution of heat. Finer cement offers a greater surface area for hydration and hence the faster and greater the development of strength. Increase in fineness of cement is also found to increase the drying shrinkage of concrete. Fineness of cement is tested either by sieving or by determination of specific surface by air-permeability apparatus. Specific surface is the total surface area of all the particles in one gram of cement. FINENESS BY SIEVING: PROCEDURE: 1. Weigh accurately 100 g of cement and place it on a standard 90 micron IS sieve. 2. Break down any air-set lumps in the cement sample with fingers. 3. Continuously sieve the sample giving circular and vertical motion for a period of 15 minutes. 4. Weigh the residue left on the sieve. As per IS code the percentage residue should not exceed 10%. PRECAUTIONS: Air set lumps in the cement sample are to be crushed using fingers and not to be pressed with the sieve. Sieving shall be done holding the sieve in both hands and with gentle wrist motion. More or less continuous rotation of the sieve shall be carried out throughout sieving. OBSERVATIONS: S.No weight of taken(g) sample weight of residue(g) Average fineness of cement = RESULT: Fineness of given sample of cement = COMMENTS: Fineness (%)
NORMAL CONSISTENCY OF CEMENT (IS: 269 - 1989 and IS: 4031 - 1988 (Part 4)) AIM: To determine the quantity of water required to produce a cement paste of standard consistency. APPARATUS: Vicat apparatus (conforming to IS: 5513 - 1976) with plunger (10 mm in diameter) balance, weights, gauging trowel. INTRODUCTION: The standard consistency of a cement paste is defined as that consistency which will permit the vicat plunger to penetrate to a point 5 to 7 mm from the bottom of the vicat mould. For finding out initial setting time, final setting time, soundness of cement and compressive strength of cement, it is necessary to fix the quantity of water to be mixed in cement in each case. This experiment is intended to find out the quantity of water to be mixed for a given cement to give a cement paste of normal consistency and can be done with the help of vicat apparatus. PROCEDURE: 1. Prepare a paste of weighed quantity of cement (300 grams) with a weighed quantity of potable or distilled water, starting with 26% water of 300g of cement. 2. Take care that the time of gauging is not less than 3 minutes, not more than 5 minutes and the gauging shall be completed before setting occurs. 3. The gauging time shall be counted from the time of adding the water to the dry cement until commencing to fill the mould. 4. Fill the vicat mould with this paste, the mould resting upon a non porous plate. 5. After completely filling the mould, trim off the surface of the paste, making it in level with the top of the mould. The mould may slightly be shaken to expel the air. 6. Place the test block with the mould, together with the non-porous resting plate, under the rod bearing the plunger (10mm diameter), lower the plunger gently to touch the surface of the test block and quickly release, allowing it to penetrate into the paste. 7. This operation shall be carried out immediately after filling the mould. 8. Prepare trial pastes with varying percentages of water and test as described above until the amount of water necessary for making the standard consistency as defined above is obtained. 9. Express the amount of water as a percentage by weight of the dry cement. PRECAUTIONS: Clean appliances shall be used for gauging. In filling the mould the operator hands and the blade of the gauging trowel shall alone be used. The temperature of cement, water and that of test room, at the time when the above operations are being performed, shall be 27 + 2 C. For each repetition of the experiment fresh cement is to be taken.

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