Experimental Study On Bonding Properties Between HRB500 Bras And Full Lightweight Concrete

The full lightweight concrete is a kind of lightweight aggregate concrete,which is made of light coarse aggregate and lightweight aggregate instead of stone and sand in common concrete,and then added with gelled material and water,and its apparent density is not more than 1950 kg/m3.The full lightweight concrete has the characteristics of light high strength,thermal insulation,good working performance and superior seismic performance.It is especially suitable for areas with insufficient bearing capacity and high seismic fortification,and the preparation of full lightweight concrete can use shale,fly ash,natural coal gangue,pumice and other waste,which is conducive to reduce the use of natural sand,stone and protect the environment,its wide application prospects.In order to promote the application of full lightweight concrete in civil engineering structure,this paper mainly studies the basic mechanical properties of full lightweight concrete and the bonding and anchoring performance of HRB500 tendons.The main work are as follows:(1)Based on the optimization of the mix design of the full lightweight concrete,the influence of the water-cement ratio,the sand rate,the aggregate strength and the pre-wetting of the aggregate on the compressive strength of the cube is analyzed,and the full lightweight concrete is analyzed by mathematical statistics and the compressive strength of 7 d,28 d and its relationship between compressive strength and axial compressive strength and splitting tensile strength.(2)Using the center pull-out test system and analyzing the influence factors of strength,the thickness of protection layer,anchorage length and bar diameter and stirrup ratio of full lightweight concrete and HRB500 bars anchorage performance,through the regression analysis of experimental data the relationship between ultimate bond strength and full lightweight concrete is obtained,which is compared with ordinary bond performance the concrete with the same anchorage conditions;The variation law of bond stress between steel bar and the full lightweight concrete was studied by the method of strain gauges.(3)On the basis of reliability analysis,the recommended values of the anchorage length of the full lightweight concrete under different strength grades are put forward and compared with the standard design value.According to the technical specification of "lightweight aggregate concrete structure" JGJ 12-2006 The specification value design is biased towards safety.