Cement, Energy and Environment

5 Flow vs. w/c for 1:6 CM Flow vs. w/c for 1:4 CM Compressive strength of Mortar The compressive strength of the mortars was examined for two flow values of 85 and 100% as per IS 2250. The details are given in Table 3. It has been observed that the compressive strength of the mortar made with Manufactured Sand is twice that of mortars made with river sand. Table3: Compressive Strength of Mortars Mortar Propor on Flow (%) Water-cement ra o Compressive Strength (MPa) River Sand Manufactured Sand River Sand Manufactured Sand 7 Days 28 Days 7 Days 28 Days 1 : 6 85 1.72 1.30 2.10 4.03 5.15 8.53 100 1.75 1.34 1.96 3.82 4.88 8.19 1 : 4 85 1.13 0.84 2.84 7.35 12.89 15.96 100 1.18 0.88 2.77 6.04 11.89 15.50 Water Reten vity Water Reten vity can be defined as the ability of the mortar to retain water against the suc on ac on of the brick or block. Certain amount of water is required for hydra on of Cement in the mortar and simultaneous development of strength. If mortar allows more water absorp on by the brick/block, it leads to low water-cement ra o in mortar and consequent incomplete hydra on of the cement in the mortar, thereby affec ng the mortar characteris cs and the bond between the mortar and brick/block. Water reten vity values for 1:6 cement mortar using river sand and Manufactured Sand were 27.3% and 28.5% respec vely. For 1:4 cement mortar it was 25.6% and 35.6% for river sand and Manufactured Sand respec vely. Thus, water reten vity of mortar was found to improve with the use of Manufactured Sand . Be er water reten vity results in be er strength and bond development. Water-cement ratio Flow(%) 160 140 120 100 80 60 40 20 0 0.75 1 1.25 1.5 1.75 2 M-Sand River Sand Water-cement ratio 0.5 0.65 0.8 0.95 1.1 1.25 Flow(%) 160 140 120 100 80 60 40 20 0 M-Sand River Sand