Experimental Study on Compressive Strength Recovery Effect of Fire-damaged High Strength Concrete after Realkalisation Treatment

Realkalisation treatment was used to recover carbonated concrete alkalinity nearby the reinforcing region at normal temperature. The feature of the realkalisation treatment which could restore concrete high alkalinity is applied for the neutralization of concrete suffered from high temperature in this paper. This paper develops important data on the application of realkalisation treatment for the mechanical behavior and durability characteristics recovery of fire-damaged high strength concrete. In this paper, the compressive strength of fire-damaged high strength concrete before and after realkalisation was investigated. The test results indicated that the realkalisation treatment results in compressive strength recovery and its effect extent depends upon exposure temperature, current density, treatment time and concentration of electrolyte. When compared with the original unfired values, the residual compressive strengths of tested specimens of cube compressive strength of 71.2 MPa exposed to temperature from 300 °C to 700 °C for two to three hours ranged from 80.3% to 39.7%, their recovered strengths were 89.6% to 61.4% after 7 days treatment. Compared with obtained experimental results of fire-damaged tested specimens of cube compressive strength of 50.2 MPa, the effect of recovered strengths is better for lower compression strength of compression cube.