Mechanical and thermal insulation performance of waste diatomite cement mortar

There are many studies on the application of raw diatomite. Still, there are few studies on using waste diatomite to partially replace cement in concrete, especially in the literature regarding mechanical properties and heat insulation. As such, many waste diatomaceous earths are buried yearly. This study used recycled diatomite to replace part of the cement (10%, 15%, 20%, 30%, 40%) to make mixed cement mortar. Various tests were performed to determine its properties and thermal insulation benefits. According to the results of multiple tests, the amount of replacement diatomite increases the amount of mixing water and setting time. The weight loss and shrinkage rates of the freeze-thaw cycles also increased. However, its water absorption and thermal conductivity decreased. Regarding compressive strength, 10% diatomite substitution had higher strength at 28 days, but 20% diatomite substitution had higher strength at 90 days. The volume change did not exceed the 0.1% critical value specified in ASTM standards. These findings indicate that the most potential results (in terms of mechanical and thermal insulation performance) can be obtained in blends with 20% waste diatomite from the brewing industry.