Influence of Addition of Gluconic Acid as a Retarding Admixture in Concrete

Due to the increasing demand for advanced high-performance concrete, research for diverse admixtures is crucial in construction scenarios like long-distance transport, hot climates, and oil well cementing. Gluconic acid (GA) is among the organic additive showing promise as a viable retarder for concrete construction. This paper presents results of a study carried out to assess and evaluate the possibility of utilizing GA as a retarder in concrete. The retarding effect of up to 0.1% GA, by weight of cement, was evaluated with a superplasticizer and compared with sodium gluconate (SG). The effects of GA and SG on the setting time, heat of hydration, adsorption, workability, compressive, flexural and split-tensile strength, and durability were investigated, along with microstructural analysis (XRD and SEM). The results showed that GA has a significant effect in delaying the setting time of cement by calcium chelation which might interfere with the growth of hydration products.