Cementitious Composite Containing Diatomaceous Earth Waste As a Pozzolanic Component

Abstract

Results showed that diatomaceous earth waste (DEW) which is rich in SiO₂, has a highly porous surface and contains more amorphous phases. DEW consists of a mixture of quartz sand and DEW particles with a high specific surface area (8755 cm²/g) and a lower apparent specific mass compared to cement, and moreover uniform particle sizes distribution. Ratio of cement/water (c/w) and setting time increased continuously with the increase of DEW addition. Water absorption and apparent porosity reduced as the addition of DEW increased, while bulk density improved and enhanced, but only up to 24 wt. % DEW, and above this it was adversely affected. Flexural and compressive strengths also improved and enhanced with enhancing DEW addition also up to 24 wt. % and then adversely affected with more addition of DEW. Therefore, the optimum addition of DEW is 24 wt. %. Portlandite or free lime test indicated that DEW showed and exhibited a strong pozzolanic reactivity due to its high content of amorphous silica. So, it could be used in the production of pozzolanic cements, mortars, and/or concretes.