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.

Influence of different additives on the rheology and microstructural development of MgO–SiO2 mixes

“…Earlier studies [49] demonstrated that a high compressive strength, along with rheological properties, were found to be influential in attaining a good dimensional accuracy in concrete 3D printing. Accordingly, early strength development, similar to those observed in RMS-OP and RMS-HMP mixes presented in this study, was also found to be critical in concrete 3D printing applications [50,51]. When these factors were taken into account, the two best-performing mixes, RMS-OP and RMS-HMP, were chosen for further analysis leading up to their future potential use in 3D printing applications.…”

Improvement of Strength Parameters of Cement Matrix with the Addition of Siliceous Fly Ash by Using Nanometric C-S-H Seeds

“…An increased amount of heat released during maturation may adversely affect the value of the rheological contraction. However, the studies presented in [62] confirm the lack of such an effect when using the NA. During the whole maturation period (from 1 to 90 days), in samples modified with FA and admixture, a lower shrinkage value was observed compared to samples without NA.…”

3D Concrete Printing: A Systematic Review of Rheology, Mix Designs, Mechanical, Microstructural, and Durability Characteristics

“…Cheng et al [ 44 ] reported an improvement in the thixotropic behavior of 3D-printable concrete with the addition of bentonite. Szostak and Golewski [ 169 ] added nano-calcium silicate hydrate (CSH) seeds in concrete and observed a reduction in setting time and a rapid increase in earlier strength. Nano-graphite platelets increase the thermal conductivity of cementitious materials and induce self-sensing capability in concrete.…”