Modification of early strength parameters of concrete by the addition of fly ash and admixture of nano C-S-H for application in 3D printing

Abstract

In the paper, the authors present the results of tests concerning traditional cement mortars with the addition of silica fly ash and the C-S-H nano-admixture. The use of fly ash results in improved plasticity of the mixture. The use of the C-S-H nano-admixture has a positive effect on shortening the setting time and a rapid increase in the strength of mixtures without losing their subsequent properties, which is presented in the research described in the paper. On this basis, the impact of fly ash and the nano-admixture on the selected parameters of the cement paste in the early maturation periods was determined – after 4, 8, 12, 24, 72h and also 7 and 28 days. The following tests were carried out on previously prepared samples: the compressive strength test on a hydraulic press, the test of setting time and the test of cement matrix shrinkage.