Effect of fly ash on frost resistance of SCC

The standard determination of frost resistance requires a long period of the test duration, especially for self-compacting concrete characterized by high performance properties. Self-compacting concrete has low water-cement ratio and, as a result, high density, strength and frost resistance, low water permeability and reduced capillary porosity. In this paper is considered a rapid evaluation of frost resistance using the method of dilatometric analysis of the structure. It is based on the dependence of frost resistance of the concrete samples on the characteristics of pore space during only one cycle of freezing and thawing. The dilatometric method is associated with the measurement of deformations of a dry and water-saturated concrete sample caused by the change in temperature, humidity, structure, and also the phase composition of the material. The study of behavior of the concrete under freezing to identify the nature of the occurrence of degradation was conducted. The three-stage water saturation of the concrete samples to determine the content of the different groups of porosity was used. The pore volume of each of the three groups was determined by weighting after each stage of saturation and expressed as a fraction of the volume of concrete. The measurement results of different groups of porosity is: P₁=5.3%; P₂ = 3.8%; P₃=2.0%; P_t = 11.1%. Frost resistance of concrete is function of porosity (P₂) and according to this parameter it can be estimated of 300 cycles. (paper)