Study On Application Of C55Machine-made Sand In Bridge Girder

In concrete industry, machine-made sand take place of natural sand with a trend ofsustainable development. It is not only to support the sustainable development of ourinfrastructure, to solve the problem of natural source shortage in some areas, but also toprotect the environment and reduce the cost of project which will have significantpractical value.First,this paper studies the machine-made sand characteristics by proceeding fromboth macro and micro aspects: the natural sand mortar compared with machine-madesand mortar under using the same graduation. research indicated that the machine-madesand has the enhancement effect on strength,but has negative effect on workability. Themorphology and composition of powder is analysis by using SEM and XRD. Testsresult found that the powder is non-vitreous,and the main component of granite andlimestone powder are SiO2and CaCO3.This paper takes cement slurry flow tests withadding and mixing different stone powder content,tests showed that powder hasadsorption to water reducer, and accelerate cement hydration reaction. Paper useuniform design method to study that under1.18mm sand particle content how influenceon machine-made sand and cement mortar performance. Raised the key sieve ofmachine-made sand is0.6mm.Secondly, this paper is based on the proportioning and performance tests of C55machine-made sand concrete and through orthogonal design method acquire the mixproportion parameter. under the same conditions,changing the fine aggregate in concreteto compared with washing machine-made sand, original machine-made sand and sandof different lithologies. The machine-made sand influence on concrete workability,mechanical properties, durability and volume deformation is studied. Moreover, thepaper discusses that machine-made sand production without water washing is possible.The results showed that:washing machine-made sand formulated C55highperformance concrete cracking total areas are320mm2/m2, early crack resistance ofClass is IV, impermeability grade is P17,56days of the electric flux is461C.In thispaper, the original machine-made sand of powder content is6.3%, methylene blue is1.0g/kg. The performance of impermeability, crack resistance and volume deformationof concrete is better than washing machine-made sand concrete. when methylene bluepowder is1.0g/kg, the high performance of high-strength concrete dust content limits may be relaxed to6%. The mechanical properties, crack resistance and volumedeformation performance of concrete mixed with machine-made sand were better thanthose of the concrete mixed with natural sand under the same conditions, but theimpermeability of concrete is not as good as mixed with natural sand; the changesmerely in lithology of the machine-made sand, had no significant effect on theperformance of concrete, when the powder content was within six percent, there was noobvious effect on the long-term performance of concrete mixed with machine-madesand.Finally, by SEM scanning electron microscopy and micro-hardness testingtechnology, the study found that the changes in lithology of fine aggregate do not affectthe morphology of concrete hydration products. the powder has filling effect andnucleation effect, appropriate amount of powder can improve the inhomogeneity of theinterfacial transition zone in concrete’s internal aggregate.The research shows that the the machine-made sand can be used in the formulationof C55concrete with high performance which is applied in bridge girder.