Effects of SNF and LS superplasticizer on cement paste using electrical measurement

Abstract

A non-contact electrical resistivity measurement is used to study the effects of sulfonated naphthalene formaldehyde condensates (SNF) and lignosulphonate (LS) superplasticizers on cement paste. Other experiments like fluidity test and test of the amount of superplasticizer adsorbed on cement particles are also carried out. Results show that SNF superplasticizer has different effects on the resistivity of cement pastes comparing with LS superplasticizer. The plot of initial resistivity versus SNF dosage can be divided into 4 zones. Each zone reflects the characteristics of SNF as a superplasticizer of cement paste, respectively. The curves of the resistivity developing with time; ρ(<i style="">t</i>), and their derivatives; dρ(<i style="">t</i>)/d<i style="">t</i>(<i style="">t</i>), have distinct changes when the dosages of SNF and LS superplasticizer are high. Electrical method is potentially a very useful method in concrete designing.