Study On Preparation And Properties Of Lightweight High Strength Concrete

At present,the laying of the railway lines,the laying of the long span bridge and the pavement and the super high rise buildings all require the lightweight and high strength of the concrete material.However,the ordinary concrete brings some limitations to the application of the special parts of the structure.Lightweight aggregate concrete has attracted more and more attention due to its advantages of lightweight,thermal insulation and sound insulation.At present,the strength of lightweight aggregate concrete is generally below 50 MPa,and the shrinkage is large and the durability is relatively poor.Therefore,a kind of lightweight aggregate concrete with high strength,low shrinkage and high durability is developed in this paper.Through the control variable method,the factors such as water cement ratio,aggregate pre wetting time,gradation mode,cement variety and mineral admixture are systematically studied to obtain more than LC50 concrete,and the strength and durability of the lightweight aggregate concrete are synthetically explored by using different concentration of sodium silicate to modify the aggregate.The microstructure and hydration products were observed and analyzed by MIP,XRD and SEM.The compressive strength of lightweight aggregate concrete increased by about 8% when the prewetting time of lightweight aggregate was 1 h,and the anti-freeze and melt damage performance was excellent,its strength increased by about 3.7%,and its anti-carbonation performance and anti-freezing and thawing ability are excellent by discontinuous grading method.The compressive strength increased by about 18.7% when mixed with fly ash(10%)and silica fume(8%).Sodium silicate was used to modify the aggregate,and its strength increased by 3%,the chloride ion flux decreased by about 412.5% and the anti-freezing and thawing performance was excellent by sodium silicate with 3%.The finite element software ANSYS was emplored to model and analysis prestressed lightweight aggregate concrete pillar.The type 93 buried cantilever pillar and pillar flange soft across a numerical analysis model for verification and optimization were established,respectively.The concrete pillar hole number and diameter of reinforced concrete pillars under the influence of load moment were all optimized.Finally,the optimum opening number of the 93 type directly buried wrists is 18,the optimum opening number of the flanged soft cross strut is 23,and the optimum diameter of the steel bar is 8 mm.It will provide data reference for the future application of lightweight high-strength concrete in prestressed pillars.