Research On Application Of Qinghai Sandstone Crushed Stone In C40 Cement Concrete

In the current process of accelerated infrastructure construction,the reduction of energy and building materials is becoming increasingly prominent.How to use local resources rationally and ensure the quality of the project has become one of the main topics studied by many scholars.As a kind of natural rock,sandstone has many types,and its properties vary greatly depending on its lithology.Relying on the Qinghai Jiaxi Highway Project,this article conducted the following research on the application of sandstone crushed stone in C40 concrete:(1)An experimental study was made on the parent rock of sandstone gravel.XRD rock analysis showed that the sandstone had 92.4%British composition.The crypto-microcrystalline quartz and the wave-shaped extinction quartz in the quartz composition had potential alkali silicic acid reaction.The half-year expansion rate of the activity test is 0.03%,indicating that it does not have alkali silicic acid activity,and the uniaxial compressive strength,frost resistance,water absorption and disintegration resistance of the sandstone are tested.And durability.(2)The saturated compressive strength of the sandstone mother rock producing crushed stone should not be less than 100MPa,and the content of the flaky granules of the sandstone crushed stone needle should not be greater than 10%;the technical indicators of the sandstone crushed stone meet the requirements of the class II aggregate Technical standard,can be used as aggregate of C30～C60 ordinary concrete.(3)Design the mix ratio of sandstone crushed stone concrete,use sandstone crushed stone and natural sand,sandstone crushed stone and sandstone machine-made sand to prepare concrete with different water-binder ratio,and linearly fit different glue-ratio to 28d compressive strength to obtain sandstone crush The empirical formula regression coefficients for estimating the water-binder ratio of the mix ratio design of stone ordinary concrete areα_a=0.66 andα_b=0.59.(4)The microstructure of sandstone gravel concrete was analyzed by SEM,and compared with basalt gravel concrete,it was found that the structure of the transition zone of the concrete interface caused by different types of aggregates was different.Stone and sandstone mechanisms are relatively loose in sand concrete structures.(5)The mechanical properties and durability of sandstone crushed stone C40concrete at different ages were studied and compared with basalt crushed stone concrete.The results showed that:under the condition of the same water-binder ratio and workability,the splitting of sandstone crushed stone and natural sand concrete The crack tensile strength is slightly lower;the compressive strength and elastic modulus of sandstone crushed stone and natural sand concrete are the best,the mechanical properties of basalt crushed stone concrete are in the middle,the mechanical properties of sandstone machined sand concrete are relatively worst,and the elastic modulus of sandstone machined sand concrete The amount does not meet the requirements of the specification and should not be used for C40 concrete;sandstone crushed stone and natural sand concrete have the best permeability resistance,chloride ion permeability,carbonation resistance,frost resistance,sulfate resistance and early crack resistance.The anti-carbonation evaluation grade is T-Ⅴ,the early cracking resistance evaluation grade is L-Ⅳ,basalt crushed stone concrete is second,and the sandstone machined sand concrete has relatively poor durability;the durability meets the design requirements of100 years.This study shows that C40 concrete made of sandstone crushed stone and natural sand with water saturated compressive strength of parent rock higher than 100MPa has good mechanical and durability properties,which can meet the requirements of engineering design indexes,and can be applied to the concrete projects under C40 and C40 of Jiaxi highway.