Benefits of adding rice straw coke powder to cement mortar and the subsequent reduction of carbon emissions

Abstract

Pozzolanic materials have been used in civil engineering applications for many years. In recent decades, waste resources have become increasingly indispensable in construction and the built environment for developing feasible ways to increase recycling incentives and avoid pollution. In this study, rice straw coke powder with high carbon content was prepared from rice straw using steam carbonization. The physical and chemical properties of the coke powder were measured using the Brunauer–Emmett–Teller method and elemental analysis. Cement mortar samples were poured containing various coke additions of 0%, 1%, 2%, 4% and 8% so that compressive strength and unit volume mass measurements could be obtained to understand the effects of the added straw coke powder on the mortar’s properties. The results showed that the rate of compressive strength increase (dpt/dt) was proportional to the square of the cement mortar strength gains’ driving capability (pe−pt). The strength evolution of the cement mortar was accurately described with a pseudo-second-order model. The highest specific gravity of the cement mortar was that containing 2% coke. The investigation into the addition of rice straw coke and the estimation of the mass of carbon fixed in the cement mortar illustrated a new possible application of this recycled agricultural waste resource. Such an application could be made for waste and carbon reduction in the construction industry, and would also lower the volume of greenhouse gases generated in civil engineering practice.