Green concrete containing diatomaceous earth and limestone: Workability, mechanical properties, and life-cycle assessment

Abstract

To arrest the growth of global environmental issues, curbing the greenhouse gas emissions and primary energy consumption in concrete production is among the efficacious strategies. Cement production being the most energy- and emission-intensive activity in concrete manufacture, the partial replacement of cement clinker with supplementary cementitious materials (SCMs), which require less intensive processing, is the effective approach. Due to the unbalanced source distribution of commonly-used SCMs, e.g. fly ash (FA) and ground granulated blast furnace slag (GGBFS), this study analyzed the substitution of Portland cement (PC) in mortar and concrete mixes with up to 40% of the highly-reactive pozzolanic diatomaceous earth (DE) with abundant deposit in western United States and many other countries, aiming to provide an alternative SCM with local availability in many regions of limited FA and GGBFS supply. The influence of DE on the density, compressive strength, workability, soundness, and environmental impacts of the production of a mix was studied at different substitution levels in binary, ternary, and quaternary systems. DE-containing mixes showed improved strength development and early properties suitable for general applications. The approach of life-cycle assessment quantified the influence of DE on environmental impacts from material production, processing, and transportation in mortar or concrete manufacture. Substitution of PC with DE at 30 wt% resulted in over ∼30% lower global warming potential and energy use as well as appreciably reduction in air pollutant emissions. The use of DE as SCMs in concrete is promising, worth the consideration regarding availability and cost.