Experimental study on fire resistance of lightweight ECC-concrete superimposed slab with steel bar truss
Lightweight ECC-concrete composite slab has the advantages of lightweight,high ductility and good crack resistance.It has a good application prospect,but its fire resistance is questionable.In order to preliminarily prove the fire resistance of lightweight ECC-concrete composite slab,fire tests were carried out on one concrete composite slab,four lightweight ECC-concrete composite slabs and one lightweight ECC composite slab,and the post fire bending test was carried out on the concrete composite slab and one lightweight ECC-concrete composite slab,focusing on the analysis of fire behavior,fire damage and mechanical performance after fire.The test results show that the spalling risk of lightweight ECC is significantly higher than that of concrete,but it has superior thermal insulation performance.If there is no spalling,the temperature of the specimen can be greatly reduced and good fire resistance can be achieved.The steel bar truss has a certain suppression effect on spalling.The greater the spacing between the steel bar truss,the worse the suppression effect on spalling.The thinner the ECC bottom layer,the lighter the spalling severity.The fire-induced spalling results in obvious reduction of stiffness and ductility of lightweight ECC-concrete composite slab.However,due to the short exposure time to fire,the extent of material degradation is limited,the residual bearing capacity of lightweight ECC-concrete composite slab is thus only 3.85%lower than that of concrete composite slab.
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