Study On Resistance To Sulfate Attack Of Recycled Aggregate Concrete

Urbanization needs a lot of concrete, which brings about the shortage of mineralresources and waste disposal problems. In order to solve environmental problems causedby waste disposal and relieve the contradiction between concrete bone materials supplyand demand, scientists start with the recycling of waste concrete. The research on basicproperties of recycled aggregate concrete is helpful to promote its commercialization ofproduction, which ultimately will achieve solutions to environmental degradation andresource shortages. However, we need to research the sulfate resistance of recycledaggregate concrete before it is large-scale applied in practical engineering.Firstly, the difference of the physical properties between recycled aggregate andnatural aggregate is researched. Then following related specification, recycled aggregateconcrete is prepared and its working performance is observing. To research the sulfateresistance of recycled aggregate concrete in sulfate solution and dry-wet circulationenvironment, experiment combined with numerical simulation is used as the mainmethods in this thesis. Compressive corrosion coefficient and mass loss rate are selectedas the evaluation index to research the sulfate resistance of recycled aggregate concrete.We focus on researching water-cement ratio, recycled aggregate replacement ratio andmineral content as the impact of sulfate resistance of recycled aggregate concrete. Usingthe curve fitting method, the experiment results are quantified to influence function. Basedon the law of substances delay, the damage decay model of recycled aggregate concrete isestablished. It can preliminarily forecast the sulfate resistance ability of recycled aggregateconcrete. Meanwhile, the following conclusions appear:(1) within a reasonable range,sulfate resistance of recycled aggregate concrete increase with the decrease ofwater-cement ratio;(2) sulfate resistance of recycled aggregate concrete decrease with theincrease of the ratio of recycled aggregate;(3) recycled aggregate concrete mixed with acertain amount of fly ash can improve the micro-structure of recycled aggregate concreteand enhance its sulfate resistance ability.