Some of the primary problems of construction are brittleness and low the mechanical properties of good thermal insulation materials. Heat-insulating foam concrete has a low thermal conductivity. However, it is practically impossible to transport it over long distances since corners are cracked during transportation, the structure is broken, and, in principle, the fragility of this material is a big problem for modern buildings. The purpose of this study was to develop a heat-insulating foam concrete with improved characteristics by experimentally selecting the optimal dosage of polypropylene fiber and a nanomodifying microsilica additive. Standard methods for determining the characteristics of fiber foam concrete were used as well as the method of optical microscopy to study the structure of the composite. It has been established that the use of polypropylene fiber with the optimal reinforcement range from 1% to 3% allows us to achieve an improvement in the mechanical and physical characteristics of fiber foam concrete. The optimal dosage of the nanomodifier introduced instead of a part of the binder (10%) and polypropylene fiber (2%) by weight of the binder was determined. The maximum values of increments in mechanical characteristics were 44% for compressive strength and 73% for tensile strength in bending. The values of the thermal conductivity coefficient at optimal dosages of the nanomodifier and fiber decreased by 9%. The absence of microcracking at the phase boundary between the polypropylene fiber and the hardened cement-sand matrix due to nanomodification was noted.
Keywords: foam concrete; nanomodification; polymer fiber; polypropylene fiber; silica fume.