Investigating the effect of adding Pumice and combining it with diatomite powder on compressive strength and water absorption of cement paste

The main material that causes aggregates to adhere to each other and forms a hard object called concrete is the cement paste. Cement paste consists of cement and water. Obviously, the higher the strength of the cement paste, the ultimate strength of the concrete made from the dough will be high. In this research, an additive material as powdered pumice of Bneh-Kohul mine near Bostan Abad and another additive as Mamaghan diatomite were added to the cement paste. Because these two materials have pozzolanic properties, they will exhibit their cementitious properties in close proximity to our cementitious materials and, as a result, are considered as cement materials. Symptoms related to the naming of different mixture ratios are clearly identified in both tables 4 and 5. In brief, the signs that contain the letter P include Pumice Powder and PD symptoms, including Pumice Powder and Diatomite Powder. The ratio of water to cement materials is considered to be 0.35 and 0.4. The results of the experiments have shown that, in terms of water absorption during treatment, all samples gradually absorb water and also show that hydration reactions of cement materials and the formation of crystals continue to occur regularly. In terms of water absorption of 28-day samples according to the ASTM standard, the results show that the porosity of our dough with different ratios of Pumice Powder  or combination of Pumice Powder and diatomite powder, and this porosity is increased by 0.35% To 0.4%. Water absorption during treatment indicates the progression of hydration reactions. While water absorption of concrete specimens at 28 days of age, according to ASTM C642-06, indicates the internal porosity of concrete, including occlusive bubbles and Capillary tubes. It should be noted that the water density of the gel was higher than that of the ordinary water and was about 1.1, and the density of the molecular water inside the crystals resulting from the hydration reactions was higher than that of the gel water. In terms of the compressive strength of doughs that only have pumice  powder additive, their 28-day compressive strength has a loss of resistance, and also for these samples at 90-day age, a slight drop of resistance is observed for the water-to-cement ratio of 0.35 However, for the 0.4% cement ratio, about 10% increased resistance. In the samples that were added to the pumice powder and diatomite powder as additive, the compressive strength changes were as follows: a) for the water-to-cement ratio of 0.35 at the age of 28 days and 90 days, an average increase of 6% Resistance is present and increases resistance for the optimum additive (25%). b) For water-cement ratio 0.4% at 28 days for 20% additive of compound powder, compressive strength reduction is noticeable, but in the 90-day life it is 5% stronger and for 25% additive compound powder at the age of 28-day and 90-day, both increase in compressive strength of 9% and 16%, respectively. Therefore, adding of the combined of Bostan Abad Pumice Powder and Diatomite Powder is recommended.