Degree of MWCNT suspension dispersity and its influence on rheology of cement pastes

Abstract

Modification of cement pastes by MWCNT (multi-walled carbon nanotubes) suspension enables to manage by their rheological properties due to the nanometer size of MWCNT. Dispersity degree of MWCNT suspension may be determined by the number of factors such as type and intensity of homogenization equipment, duration of homogenization and some other. The aim of present research consists in the establishment of optimal methodology of MWCNT suspension homogenization and investigation of dependence between dispersity degree of MWCNT suspension and rheological properties of cement pastes with that suspension. Two types of homogenization methods of MWCNT were tested such as ultrasonication and homogenization based on rotor-stator principle. The ultrasonication treatment about 6 min was established as optimal homogenization technique in the course of the current research. The yield stress and plastic viscosity of cement paste modified by MWCNT suspension increased in comparison with cement paste modified by polycarboxylate ether plasticizer (PCE) in 5 and 30 min after cement pastes mixing. Time of ultrasonication of MWCNT suspension more than 6 min did not have the influence on rheological behaviour of cement pastes. Addition of MWCNT decreased the volume coefficient of water bleeding of cement paste with PCE by 18%.