Environmental and Economical Aspects of Partial Replacement of Ordinary Portland Cement with Saudi Raw Minerals

Abstract

This study aims to utilize a local natural mineral material from different places in western area of Saudi Arabia namely, (Osfan, Alkamel, Wadi starah, Khulais, Jeddah and Alghowla) as a partial replacement of Ordinary Portland Cement (OPC) in order to increase its productivity, minimizing the problems associated with its production in terms of energy consumption and air pollution. In addition to the reference sample (C:100% wt. OPC), other six mixes were prepared containing 75 wt.% of OPC and 25 wt.% of each raw mineral. They were denoted as C1, C2, C3, C4, C5 and C6. Different cementing, sintering, chemical and mechanical properties of the prepared mixes were tested according to the international standard specifications. It was concluded that OPC blended with 25 wt.% of local natural minerals from Jeddah (C5), Wadi starah (C3) and Alkamel C2 show outstanding cementing and mechanical properties compared with the reference sample. They recorded relatively longer setting time ranges 55–160, 52–145 and 52–144 min respectively compared with the reference sample (C) which recorded only 48–120 min. Relatively higher percent of combined water (23.75–28.23, 20.84–24.59, 16.34–19.31%), respectively at different ages of hydration, compared to the reference sample (C) that recorded 15.59–18,00%. The samples showed higher heat of hydration 81–97, 77–94, 75–90 cal/g, compared with reference sample which recorded 70- 85 cal/g, higher bulk density 1.61–1.96, 1.66–1.84 and 1.65–1.84 g/cm3, respectively compared with the reference sample that recorded 1.61–1.84 g/cm3, lower apparent porosity of (10.41–15.02, 12.75–16.25, 13.96–17.40%), respectively whereas the reference sample noted (14.39–24.11%) and relatively higher values of compressive strength (90–125, 80–120, 75–113 kg/cm2), respectively compared with the reference sample which recorded (60–110 kg/cm2). The remaining samples C1, C4 and C6 showed less cementing and mechanical properties compared with the reference sample (C). The improved properties of C5, C3 and C2 are due to their relatively higher content of portlandite mineral {Ca(OH2)} one of the main hydration products of Portland cement, as well as their relatively better microstructure.