Synopsis
The rates of development of shear modulus of three fresh Portland cement pastes, two containing accelerating admixtures and one containing a retarding admixture, were compared with the shear modulus of a control mix during the, first few hours after mixing. It was found that the shear modulus equipment used was sensitive enough to detect differences in structure development between the mixes.
The initial setting times were determined using the Vicat apparatus and it was observed that the mixes had diferent shear modulus values at their Vicat initial setting time. However, average shear moduli of at least 1970 k Pa had been reached in all cases by the Vicat initial setting time, with the maximum shear modulus of 3270 k Pa being measured for the control mix without additives.
