Improving the behaviors of foam concrete through the use of composite binder

Abstract

The most important task in the production of foam concrete is the selection of silica-containing components from both natural and technogenic raw materials, the use of which can not only reduce the consumption of the most energy-intensive and expensive component of foam concrete/Portland cement, but also allows to control the process of structure formation. The novelty of the paper is to identify the scientific patterns of the process control to foam concrete microstructure formation by using the system “Portland cement - opoka marl-fly ash” as a composite binder. The composite binders obtained by mechanochemical activation of Portland cement, opoka marl and fly ash were prepared as the novel compositions, based on which the concretes with improved behaviors are created. The physico mechanical characteristics of the concretes were researched by a series of tests including heat intensity of hydration, shrinkage, average density, and compressive strength, in addition to the durability characteristics (freeze-thaw resistance, vapor permeability) and thermal conductivity. The morphology and microstructure of the obtained cement pastes and concretes was studied by a complex of methods, including SEM images, XRD analysis and DTA analysis. For the first time, the scientific data on the properties of the composite binders and the foam concrete based on it were obtained. The nature of the influence of fly ash on the microstructure formation processes of the foam concrete mix for wall materials is revealed. The composite binders obtained by milling components have a compressive strength of up to 60 MPa with cement savings of up to 40%. Based on the composite binder, the foam concrete with a density of 500–700 kg/m3 with a compressive strength of up to 4.26 MPa were obtained.