Study on Properties of Concretes with Manufactured Sands with Typical Lithology in Railway Engineering
In order to discuss the applicability of manufactured sands with different lithology in railway concrete,manu-factured sands with typical rock types including limestone,quartzite,conglomerate,granite and basalt commonly used in China were used to study the developmental rules of workability,compressive strength and durability of manufactured sand concrete in railway engineering.The results show that the manufactured sand with limestone,quartzite and con-glomerate has good physical properties and stable chemical properties,with better workability,compressive strength and durability than those of river sand concrete under the positive effect of stone powder filling.Basalt manufactured sand with high methylene blue value and high water absorption,which is adverse to the maintenance of concrete workability,increases the internal water saturation of concrete,and significantly reduces the frost resistance of the concrete.The high mica content in granite manufactured sand leads to the intercalation adsorption of admixture,which reduces the air en-trainment effect and frost resistance of hardened concrete.The electric fluxes of all manufactured sand concretes are less than 1 234 C,with the chloride ion diffusion coefficients less than 9.5x10-12m2/s,indicating good resistance to chlo-ride ion penetration.The higher volume fraction of harmful pores in granite manufactured sand concrete leads to its resist-ance to chloride ion penetration lower than that of concrete with other lithological manufactured sand.
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