Experimental Research On The Effect Of Fireproof Coating On The Performance Of Concrete Exposed To High Temperature

As the most widely used civil engineering material,strengthening the fire resistance of concrete is the key to improve fire limit of the main load bearing structures of buildings.Fireproof coating have been used in some important reinforced concrete buildings to increase their fire resistance currently.In order to further explore the effect of fireproof coating on the mechanical and durability properties of concrete after high temperature,specimens with non-intumescent fireproof coating(5mm,10 mm,15mm)and intumescent fireproof coating(1mm,1.6mm,2mm)were taken as research objects in this paper.Specimens were heated to four target temperatures(200?,400?,600?,800?)and then were cooled down to room temperature.Following researches were carried out separately:The center temperature of specimens during heating process was measured.Temperature field change of concrete during the whole process of temperature rise and fall under working condition of 800? was studied.Concrete temperature field was simulated and compared by ABAQUS.The effect of fireproof coating on temperature change of concrete under high temperature was analyzed.Results showed that fireproof coating can delay temperature rise and reduce internal temperature of concrete.The effect of fireproof coating on the fire resistance of concrete was studied that the compressive strength,splitting tensile strength,elastic modulus,water absorption performance and carbonation resistance of concrete after high temperature were measured.Test results showed that fireproof coating can improve the mechanical and durability properties of concrete after high temperature.The effect regular patterns of fireproof coating on the mechanical and durability properties of concrete after high temperature were obtained so that difference in the protective effect of two kinds of fireproof coating was cleared.Specimens with non-intumescent fireproof coating were heated to target temperatures under different heating rates(5 ?/min,10?/min,15?/min).The compressive strength,splitting tensile strength,water absorption performance and carbonation resistance of concrete after high temperature were measured.Test results showed that the lower the heating rate,the lower the mechanical properties and the worse the durability properties of concrete with non-intumescent fireproof coating.Specimens with non-intumescent fireproof coating exposed to high temperature were cooled down to room temperature by natural cooling and water cooling,respectively.The compressive strength,splitting tensile strength and carbonation resistance of concrete after high temperature were measured.Test results showed that the mechanical and durability properties of specimens cooled in water were obviously lower than those of specimens cooled in air.Fireproof coating can reduce the damage to concrete caused by water cooling.Residual mechanical properties of concrete were analyzed theoretically based on the test results.The calculation formulas of compressive strength reduction coefficient,splitting tensile strength reduction coefficient and elastic modulus reduction coefficient of concrete with fireproof coating after high temperature were established.Applicability of the calculation formulas were verified by comparing calculated values of formulas with experimental values of related references to provide a reference for fire resistance design of concrete structures and damage assessment of concrete structures with fireproof coating after fire.