Hornikovska I. Non-autoclave foam concrete for layers of road constructions of highways

The dissertation is devoted to the development of the theoretical foundations of the technology of dispersed reinforced non-autoclaved foam concrete with specified construction, technical and stress-related properties for the possibility of its use as a heat-insulating layer of road surface dressing. In the course of the research the following results were achieved: the effective foam concrete compositions were designed; the construction and technical properties of foam concrete were investigated; the industrial-research and practical approval was carried out; the technical and economic efficiency of using non-autoclaved fiber-reinforced foamed concrete in highways surface dressing was calculated. The thesis studies the matters of improving the performance properties of non-rigid roads by replacing the frost-resistant layer made of building sand with a layer of monolithic 21 non-autoclaved foam concrete reinforced with polypropylene fiber grades of density D600, D800 and D1000. The existing approaches to the use of non-autoclaved foam concrete as road surface dressing layers are analyzed in order to eliminate the effect of frost lift of the subgrade in Ukraine. According to the developed block diagram of studies, the basic physical, mechanical, thermotechnical, power and energy characteristics of the fracture strength of non-reinforced foam concrete and dispersed non-autoclaved foam concrete reinforced with polypropylene fiber grades of density D600, D800, D1000 were analyzed in stages. The method of mathematical and statistical modeling was used to determine the optimum composition of fiber-reinforced foamed concrete. The research of the fracture strength of non-autoclaved foam concrete of unreinforced and reinforced with polypropylene fibers was done. The studies were carried out according to the criteria of fracture mechanics in order to determine the strength and stress-related properties of the developed foam concrete. In addition, the study of the elasticity coefficient by the method based on the equality of the values of concrete elasticity coefficient under compression and tension using the dependency diagram "load-deformation" was performed. It has been established that reinforcing non-autoclaved foam concrete with polypropylene fiber increases both the strength and stress-related properties, as well as the power and energy parameters of the fracture strength of the material, and also inhibits the fracture process from the moment of the development of the highway cracks to its complete defragmentation. In the dissertation, it is proposed the methodology for calculating the value of the antifreeze layer using a monolithic non-autoclave fiber-reinforced foam concrete and nomograms to determine the required value of the antifreeze layer made of a monolithic non-autoclave structural-heat-insulating fiber-reinforced foam concrete of grades of density D600–D1000. Research and industrial approval of the use of monolithic non-autoclave structural and heat-insulating fiber-reinforced foam concrete of the calculated thickness as an antifreeze layer of road surface dressing for the construction of individual sections of highways, access roads and internal development roads, pedestrian areas at the objects of construction and reconstruction of the transport infrastructure was performed. It was calculated the economic effect of replacing the antifreeze layer of road surface dressing made of building sand with non-autoclaved fiber-reinforced foam concrete of the corresponding class which amounts to 7,3% of the cost savings. It has been established that the use of this material as an antifreeze layer of road surface dressing 2.5 times increases the overhaul cycle of operation of a non-rigid road transport network.