Effectofmixing Method And Curingconditions On The Performance Of Different Types Offineaggregate Concrete

This paper mainly studied the effects of improved mixing method(sand-wrapped stone method)and curing conditions on the performance of concrete made from ordinary sand and manufactured sand for fine aggregates.The mechanism of action was analyzed,and river sand was used as fine aggregate.In the case of scarcity of natural sand and gravel resources,the use of new mixing methods and curing conditions to study the application of a new type of fine aggregate(manufactured sand)in concrete.The main research contents are as follows:The fineness modulus,apparent density,bulk density,water absorption,porosity,stone powder content,particle grading,and other physical properties of ordinary sand and manufactured sand were measured,and sand stone method was determined as improved mixing process,natural curing and standard maintenance are the two conservation conditions in this article.By measuring the consistency,air content,bleeding rate,compressive strength,electric flux and carbonization depth of concrete,the influence of improved mixing method on the performance of different types of fine aggregate concrete was studied,and the mechanism of action was analyzed.The results show that improving the mixing method can improve the flow ability,cohesiveness and water retention of different types of fine aggregate concrete.The reason may be that the improvement of mixing method is mainly to reduce the production of coarse aggregate and cement in the first step.The main is the solid-air interface,reducing the water-cement ratio of the shell pulp,shell-like pulp like countless "sponge",hindering the release of water in the slurry.The improvement of the mixing method can improve the compressive strength of different types of fine aggregate concrete.With a water-cement ratio of 0.5,the 28-day and 12.5%,9.4%increase in the strength of the concrete prepared using the river sand as the fine aggregate was improved by the mixing process,respectively;the 28-day strength improvement of the concrete prepared using the ordinary mechanism sand for the fine aggregate was 14.2%,7.5%;Strength of concrete made with fine sand as fine aggregate was increased by 8.7%and 12.1%respectively for 28 days;at a water cement ratio of 0.3,the 28-day strength improvement of the concrete prepared using the ordinary mechanism sand for the fine aggregate was 4.9%,5.4%.The reason may be that the improvement of the mixing process changes the degree of hydration of the cement in the inter facial transition zone.The conventional mixing method makes the surface of the aggregate too high to form a water film due to a one-time addition of water.At the cross section,there are less C-S-H gels,while the improved mixing process cement is in full contact with the aggregates,forming more gels,and the inter facial transition zone has enhanced adhesion.Improved mixing method can improve the durability of different types of fine aggregate concrete.The reason may be that the improved mixing process can make the cement can evenly and fully combine with the coarse and fine aggregate,avoid forming cement groups,increase the dispersion degree of the cement,and reduce the hardening of the concrete.Porosity reduces the amount and rate of chloride ion and C02 infiltration.The effect of curing conditions on the compressive strength of different types of fine aggregate concrete was studied.The results show that compared with natural conservation,standard curing can improve the compressive strength of different types of fine aggregate concrete at different ages.With a water-cement ratio of 0.5,the 28-day and 12-percent increase in the strength of the concrete prepared using the river sand as the fine aggregate was improved by the mixing process,respectively;the 28-day strength improvement of the concrete prepared using the ordinary mechanism sand for the fine aggregate was 14%,14%;Strength of concrete made with fine sand as fine aggregate was increased by 8%and 14.5%respectively for 28 days;at a water cement ratio of 0.3,the 28-day strength improvement of the concrete prepared using the ordinary mechanism sand for the fine aggregate was 4%,12%.The reason is that the normal hydration and normal humidity under normal maintenance,and the cement hydration rate is low,hydration.The product can fully diffuse into the gaps of the cement particles to form a uniform cement stone structure.The concrete has a higher strength in the later period.Under the normal humidity conditions,the internal and external humidity of the concrete have a small difference,which can ensure the effective hydration of the concrete and improve the internal structure of the concrete.,Strengthen the concrete compressive strength.The effects of improved stirring process on the micro structure in-homogeneity of the machined sand concrete were investigated by MIP.At the same time,the effect of improved stirring on the micro structure homogeneity of the machined sand concrete was investigated through core sampling strength testing.The results show that the improved mixing process can reduce the harmful pores of the concrete,improve the distribution of pore size,and improve the non-uniformity of the micro structure of the concrete.The improved mixing process can reduce the non-uniformity of the strength of the concrete components and improve the macroscopic uniformity of the concrete.