Date: 9/ 04 / 20 mm EXPERIMENT NO. 4 AIM: To determines the effect of w/c ratio on the compressive strength of the concr

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Date 9 04 20 Mm Experiment No 4 Aim To Determines The Effect Of W C Ratio On The Compressive Strength Of The Concr 1 (110.17 KiB) Viewed 27 times

Date: 9/ 04 / 20 mm EXPERIMENT NO. 4 AIM: To determines the effect of w/c ratio on the compressive strength of the concrete. APPARATUS: Balance, mould of size (15 cm x 15 cm x 15 cm), vibrator ctc. THEORY: Strength of concrete primarily depends upon the strength of cement paste and the strength of the paste increase with increase in cement content and decreases with air and water content. The strength of concrete to only dependent upon watcr-cement ratio provided the mix is workable for given cement and acceptable aggregates. The strength that may be developed by workable, properly placed mixture of cement, aggregate and water is influenced by. 1. Ratio of cement to mixing water. 2. Ratio of cement to aggregate. 3. Grading, surface texture, shape strength and stiffness of aggregate particle 4. Maximum size of aggregate. The w/c ratio primarily affects the strength whereas the other factors indirectly affect the strength of concrete by affecting the w/c ratio. PROCEDURE: In order to cast 6 concrete cubes take 8.34 kg of cement, 18.3 kg of fine aggregate and 33.6 kg of coarse aggregates i.e. 1:2.5:4. Spread out the measured quantity of the coarse aggregate and fine aggregate in alternative layers on an impervious concrete floor. Pour the cement on the top of it and mix them. Mix by a shovel turning the mixture over and over again until uniform colour is achieved. Add water as per the specified w/c ratio and then mix properly and drain continuously till a good, uniform and homogenous concrete is obtained. After mixing the concrete is filled into a mould of size 15 cm x 15 cm x 15 cm. compact the concrete on a vibrating table. After the top layer has been compacted brought to a finished level with the help of a mould using trowel. The test specimens are stored in a place free from vibrations in moist air of at least 90% relative humidity and at a temperature 272°C for 24 hrs, from the time of addition of water to the time for drying the ingredients. After this period the specimens are marked and removed from the mould and immediately submerged in clear fresh water and kept there until taken out just prior to teat. Set of three cubes is tested for compressive strength after three days and remaining three cubes are tested after thirty five days.