Humic acid-based superplasticizer for sustainable concrete

Abstract

Superplasticizers are polymeric agents that improve the workability of fresh concrete and improve the mechanical properties of hardened concrete by reducing the required amount of water in the mixtures. Commonly used superplasticizers are not regarded as ecoefficient products due to their high energy consumption and high cost of raw material used in the production. There are studies in the literature on the use of humic acid as a dispersant, acting as a superplasticizer and created an intermolecular separating force by electrostatic repulsion and steric hindrance. However, the published literature is lack of studies on the use of humic acid as a superplasticizer in cementitious systems. The aim of this study is to investigate the plasticizing efficiency of a commercially available humic acid (HA) based solution, which is actually obtained from leonardite for agricultural use, in cementitious systems as well its effects on hydration and mechanical properties of the systems at various dosages. HA based solution was evaluated comparatively with respect to lignin based and naphthalene-based superplasticizers. HA based solution showed a plasticizing efficiency similar to lignin and the naphthalenebased product. The results suggest that humic acid-based agents should be considered as eco-efficient superplasticizers due to the similar performance on workability, hydration kinetics and mechanical properties of cementitious systems when compared to naphthalene-based superplasticizer