Increase of Temperature and Fire Resistance for Reinforced-Concrete Structures by Surface Treatment with Protective Coating

摘要

Purpose of the study was to research the effect of protective coating, based on polysiloxane filled with oxide components, on temperature and fire resistance of reinforced-concrete structures. Influence of hardening conditions on micro-hardness of the coating was studied in different regimes. It was found that, regarding the process conditions of hardening, energy saving, and satisfactory indicators of micro-hardness, it is reasonable to use quite simple regime to obtain the protective coating, namely, 24 hours at room temperature (293 K). Dependence of coating swelling factor on its thickness and heating rate/temperature was found, thus indicating its parameters in wide range. So, when heated up to 573 K, the swelling factor depends on thickness and heating rate. Optimal hardening regime of protective coating was found for concrete surfaces: heating up to 473 K or keeping at room temperature for 24 hours. It was proved that, at change of coating thickness from 300 to 800 urn (due to expansion), porosity index grows in 5.0-7.5 times; at change of temperature gradient from 20 to 60 degrees/minute - in 8.2-9.4 times. Effectiveness of fire protection with developed coating compounds for reinforced-concrete structures has been proved. At their use fire-resistance limit of reinforced-concrete structures for the termal insulating capacity increases by 1.8-2.1 times. Effect of coating thickness on the total porosity index during thermal-oxidative degradation of polysiloxane film-forming material (in temperature range 573-873 K) has been studied. It was found that increase of the total porosity index, by 6-16%, occurs at heating up to 573 K and coating thickness 400-600 um. Obtained results confirm the practicability of applying the developed coating compounds, based on polysiloxane filled with oxide and silicate components, for increasing the fire resistance limit of reinforced-concrete structures by loss of thermal insulating capacity in 1.8-2.1 times.