Cement Energy Environment

34 Mortars by replacement with 10%, 15% and 20% of PP+ were made with Ennore Sand. The compressive strength was determined, namely Compressive strengths of PP+ additive mortars made from different dosages of PP+ additive and cured for 28 days at room temperature. The results showed that compressive strength increased with the increase of surface area of PP+ additive. Higher surface area means smaller particle size. Because of smaller size, dissolution of PP+ additive in water was more, leading to the formation of a larger amount of C-S-H gel. This is responsible for higher compressive strength in the mortar. The different mineral phases within the cement hydrate with different rates forming various reaction products. Some products deposit on the unreacted cement particle surfaces (surface products) while others form as crystals in the water-filled pore space between cement particles (pore products). For simplicity, cement paste can be thought of as consisting of four phases: (i) unreacted cement, (ii) surface products (like C-S-H), (iii) pore products (like calcium hydroxide), and (iv) capillary pore space. PP+ reduces CH and increases C-S-H. Surface products grow outward from the unreacted cement particles and contain connected (percolated) gel pores, while pore products are generally polycrystalline and fully dense, with no connected pores. The capillary pores are the water-filled space between solid phases and generally range from about 0.01 to 0.1 micrometers in size, in a reasonably well hydrated Detail 3 Days (In Mpa) 7 Days(In Mpa) 28 days(In Mpa) Mix-1 32.5 38.00 50.9 Mix-2 36.2 43.8 58.4 Mix-3 40.6 48.4 65.2 Mix-4 38.5 44.7 59.7 Figure 3: Compressive strength of different mixes of PP+ cement paste, although during early hydration, they can range up to a few micrometers in size. These pores are responsible for water percolation in the mortar and concretes. The percent water percolation for mortars in the presence of PP+ is shown in figure 5. The presence of PP+ during hydration reduces the pore size, giving a dense structure. This is because of the formation of additional amount of C-S-H. Due to decrease in pore size and pore size distribution the water percolation decreases. From figure 5, it is apparent that in the presence of PP+, the structure of hydration products is denser and as a result the water percolation is decreased.