Cement Energy Environment

33 Following mixtures were mixed separately in order to have water/solid (w/c) ratio of 0.35, 2 g each of OPC and 10%, 15% and 20% PP+ were mixed with 1 ml of water in different plastic vials. Each Vial was then vibrated for about 30 seconds and then placed into the calorimeter chamber immediately. The rate of heat evolution and total heat evolved were determined as a function of time. The mortars were thoroughly mixed in Hobart mixer. Each mortar was placed in a mould as per IS 2645. After 24 h, the mortars were demoulded and immersed in water tanks separately for 20 days. The moulds were then fixed in a permeability apparatus where pressure of 2.0 kg/cm 2 was applied (pressure was slowly increased from 0.5 kg/cm 2 to 2.0 kg/ cm 2 ). Water percolation was measured every 1h in terms of weight of percolated water for 8 h. Powder X-ray diffraction patterns were recorded with X-ray diffractograph using CuKa radiations. Figure 2:Rate of heat evolution as a function of time Heat evolved during hydration as a function of time is illustrated in Figure 2. It is clear that heat evolved increased with time and the value is maximum in the presence of PP+ with 15% dosage. PP+ powder having smaller size and crystalline in nature might be participating in hydration reaction, giving more heat and accelerating the process. i. 140 g OPC + 700 g sand ii. 126 g OPC + 14 g PP+ + 700 g sand iii. 119 g OPC + 21 g PP+ + 700 g sand iv. 112 g OPC + 28 g PP+ + 700 g sand Compressive strength of cement mortars [OPC:sand-1:3] in the absence and presence of PP+ at different intervals of time were determined with the help of compressive strength testing machine. X-ray diffraction studies Results and Discussions Determination of heat of hydration Determination of water percolation by permeability apparatus Determination of compressive strength