The influence of active mineral additives on properties of concrete for 3DСP

The purpose of the study is to develop cement fine-grained concrete modified with active mineral additives for 3D concrete printing (3DCP) with optimal rheotechnological properties of raw mixtures and physical and technical characteristics of hardened composites. In the research materials were used that met the requirements of GOST 59097-2020, as well as standard test methods. The molding of the samples was carried out on a portal construction 3D printer AMT S-6044. It has been established that the studied active mineral additives help to reduce the ultimate shear stress of mixtures by 9-48% compared to the control composition. The average density of concrete mixtures increases slightly with the introduction of active mineral additives in amounts up to 10%; a further increase in their content reduces the average density by up to 13%. It has been established that the best performance in terms of increasing dimensional stability (by 16-81%) is achieved by modifying with diatomite, microsilica, kaolin and metakaolin in an amount of 10%, and with biosilica and wollastonite in an amount of 10-20% by weight of Portland cement. In this case, there is a decrease in the values of the maximum shear stress of the mixtures by up to 43%, which is sufficient for the underlying layers to absorb loads from the layers newly laid on them using the layer-by-layer extrusion method. It was determined that metakaolin has the highest efficiency among the studied active mineral additives in terms of increasing the tensile strength of hardened composites. If the content of metakaolin is in an amount of 10% by weight of Portland cement, the compressive strength increases by 19%, and by 35% in bending.

Author: R.Kh. Mukhametrakhimov

Section: Science and production

Keywords: concrete, additive manufacturing in construction, 3DCP, active mineral additives, rheotechnological properties, strength.