Effects of mineral admixtures and superplasticizers on micro hardness of aggregate-paste interface in cement concrete

This paper presents quantitatively the results of an experimental investigation on influence of mineral admixtures and superplasticizers on Vickers micro hardness (HV) of aggregate-paste interface in cement concrete. The HV was measured by Vickers hardness testing equipment. The results indicate that addition of fly ash decreases HV of the concrete. Although it decreases with the increase of ground granulated blast furnace slag (GGBS) replacement, the HV is higher than that of concrete containing fly ash at all replacements. The flying ash and GGBS composition increases HV in later curing ages, but does not improve it in early curing ages. Aminosulfonic acid based superplasticizer and aliphatic hydroxy sulphonate condensate superplasticizer can enhance HV in early curing ages. The HV of concrete with polycarboxylic acid superplasticizer is higher in later curing ages.