Dolomitic Limestone Powder: Cement Substitute in the Production of Structural Concrete Paving Blocks

Abstract

Manufacturers are replacing or combining cement with mineral additives such as slags, natural pozzolans, sand, diatomaceous earth and limestone to reduce carbon dioxide emissions and energy usage. Due to its high magnesium content, dolomitic limestone has long been utilized in concrete production to reduce costs and environmental risks associated with making cement. This study aimed to produce a reliable and appropriate concrete mixture for concrete paving blocks using dolomitic limestone powder that passed the no. 24 sieve as cement replacement at replacement levels of 0 (control mix), 8, 12, 16, 20, 24, 28 and 32%, satisfying the minimum compressive strength requirement for structural concrete of 20.7 MPa (3,000 psi). The ASTM E877-13 was used to sample the dolomitic limestone, and the 1:1.5:3 concrete class combination was utilized to proportion the quantities of cement, sand and aggregates (3/8”). After 28 days, the specimens were cured and the compressive strength, through the varying water-cement ratios in the concrete mixture, was determined. Results showed that dolomitic limestone powder can substitute cement by 16% by weight, using a concrete mix of 523-g cement, 936-g sand, 1,868-g gravel, 100-g dolomitic limestone powder, and 166-g water with a water-cement ratio of 0.318, exceeding the minimum necessary compressive strength of concrete of 20.7 MPa by 24.9% or 5.16 MPa. Therefore, it is advised to utilize this proven concrete mixture as a basis for a potential business venture in the production of concrete paving blocks for structural concrete applications such as walkways, sidewalks, parking lots and commercial areas, as well as in places where loads are very high, like airports, courtyards, docks and freight yards.