Complex Modification of Cement Matrix and Bloated Vermiculite Surface to Increase the Strength of Heat-Izolating Constructional Blocks

Abstract

The technological and structural prerequisites for increasing the strength of heat-insulating structural blocks based on expanded vermiculite without significantly increasing cement consumption have been considered. The scientific idea of the work lies in the comprehensive modification of the "cement matrix - vermiculite aggregate" system, including the introduction of microcrystalline, fly ash, and superplasticizer into the binder composition, as well as sequential treatment of the vermiculite surface with NaOH solution, liquid glass, and the GKJ-11 hydrophobizer. It has been shown that the increase in strength is determined not only by the compaction of cement stone and the formation of additional hydrosilicate phases but also by the state of the interphase transition zone. Based on the results of composition analysis, X-ray phase data, and microstructural images, it is substantiated that complex treatment reduces the open porosity of the filler surface, increases adhesion, and forms a more stable "filler-cement stone" contact. The proposed approach ensures a rational combination of low density, thermal insulation efficiency, and increased operational reliability for vermiculite blocks.