Admixture optimization in concrete using superplasticizers

Abstract

The main goal of this paper is to optimize superplasticizer admixtures in concrete in order to reduce the amount of Portland cement in concrete mixtures. There are two main positive impacts of decreasing the amount of Portland cement: first, less cement in concrete reduces the CO2 that is released into air, so it is more environmentally friendly, and second, less cement reduces the production costs of concrete. Two types of superplasticizers were used with different dosages of admixture. In the first type, dosages were 0.8 and 1.0% (per weight of cement) and in the second type they were 0.9 and 1.1% (per weight of cement). Workability, porosity, compressive strength, granulometry and microscopy tests were conducted for a large number of sample formulations. Compressive strength was tested after 7, 14, 21 and 28 days of curing. The results show the optimal ratio of fine and coarse aggregate, the optimal amount of water, the optimal mixture of cement and aggregates, and the optimal dosage of superplasticizer to increase workability and compressive strength and reduce the cement/water ratio.