Geochemical and Experimental Investigations of some Egyptian Volcanic Tuffaceous Rocks as Natural Supplementary Cementitious Materials

Abstract

Supplementary cementitious materials are additives that are used to improve the qualities of Portland cement while also reducing its environmental impact. The production of such blended cements relies on the regional availability of additional components. Despite the prevalence of volcanic tuffs in the Eastern Desert and South Sinai encountered in Egypt, there is a scarcity of knowledge regarding experimental research on cement manufacture. The main objective of this study is to analyze the geochemical and experimental characteristics of several volcanic tuffaceous rocks exploited as natural additional cementitious materials and their impact on the characteristics of the resulting blended cement. The partially replacement can play an important role in reducing the local environmental impacts (CO2 emissions). Various volcanic rock specimens have been collected from the Sinai (Wadi Kid) and the Eastern Desert (Gabal Umm Zarabit, Wadi Umm Khariga, Gabal Igla El-Iswid, and Abu Wassat), Egypt. The samples under study were examined for their mineralogy, petrography, and chemical composition in order to identify their specifications. In addition, a total of fifteen blended cement samples were produced by partially replacing clinker with the investigated samples. The substitution ratios used were 10%, 20%, and 25% by mass. A control mix was also designed, consisting of ordinary Portland cement without any other substances. An assessment has been conducted on the effects of partially replacing clinker with volcanic rocks on the characteristics of the resulting blended cement. The physico-mechanical parameters, including Blaine, setting time, flexural strength, and compressive strength, of the hardened blended mortars were measured at specific times (7 and 28 days). The study demonstrated that the strength of the studied blended cement mixes decreased as the fraction of the examined volcanic rocks to clinker ratio increased throughout the early stages. The highest compressive strength among the mixtures evaluated was achieved when using a 10% ratio of volcanic rocks as clinker replacement.