Study On The Mechanical Properties Of Concrete With Manufactured-sand In Severe Environment

With good material properties,manufactured sand has wide source of raw materials whose production quality is controllable.During concrete production,replacing natural sand with manufactured sand can not only meet the design requirements,but also save cost.In recent years,manufactured sand has been widely used and promoted in concrete projects.Concrete is a kind of widely used building material which is often used in severe environments.Therefore,it may be damaged by high temperatures,freeze-thaw cycles and chemical attacks inevitably.Currently,studies on mechanical properties of concrete with manufactured-sand in severe environment are few systematic.Research data about mechanical properties of concrete with manufactured-sand brought by freeze-thaw cycles or high temperatures is also less.Researches mainly focus on effects of the performance of single strength grade of raw materials on working performance,instead of a plurality of strength contrasts.Experimental studies on chemical attacks of concrete with manufactured-sand after freeze-thaw or high temperatures are rare.In this paper,mechanical properties and durability of concrete with manufactured-sand in severe environment are researched.The paper focuses on the following aspects:1.Freeze-thaw cycle tests of general concrete with manufactured-sand in different intensity levels were carried out,until concrete achieved freezing standard.Mechanical properties tests of concrete with manufactured-sand after freeze-thaw were done to analyze relationship between residual compressive strength of cubes and freeze-thaw cycles of concrete with manufactured-sand after different freeze-thaw cycles.The formula for calculating the residual strength of concrete with manufactured-sand of different intensity levels after freeze-thaw and the conversion coefficient of engineering were put forward.2.Experimental studies about Chemical attack of concrete with manufactured-sand after freeze-thaw cycles were carried out.In different erosion environments,mechanical properties of machine-made sand concrete were tested and compared.With freeze-thaw and erosion,the deterioration of material properties of concrete was summarized,and the damage mechanism was analyzed.3.Experimental studies about mechanical properties of concrete with manufactured-sand of different intensity levels after high temperatures were carried out.Effects of different temperatures on the strength of concrete with manufactured-sand were analyzed and the trend line between the relationship of residual strength and temperatures after high temperatures was put forward.Taking C60 as an example,the relationship between stress and strain was studied.An improved JNM model with temperature coefficient was presented.4.Experimental studies about erosion-resisting characteristics of concrete with manufactured-sand after high temperatures were carried out.In different erosion conditions,mechanical properties of machine-made sand concrete were tested and compared.With high temperatures and erosion,the deterioration of concrete with manufactured-sand was summarized,and the damage mechanism was analyzed.5.Compression process of concrete with manufactured-sand was simulated with ANSYS software.The destruction of concrete was analyzed from the microscopic view.Furthermore,numerical simulations of freeze-thaw and high temperatures were carried out.Under different conditions,the stress concentration,strain variation and displacement combined value in the concrete were analyzed.