Study On Influence Of Carbonation And Ammonium Sulfate Erosion On The Mechanical Properties Of Concrete Under Stress

In this paper,under the background of environmental problems such as residual ammonium sulfate mother liquor caused by "in-situ leaching method" used in ionic rare earth mining areas,the effects of carbonation,stress level and ammonium sulfate solution on the mechanical properties of concrete were studied.Based on two kinds of engineering reality,two groups of tests were set up.By ammonium sulfate was carried out on the compressive stress state of concrete corrosion test and carbonation and ammonium sulfate solution alternating corrosion test,find out the ultimate compressive strength of concrete,the change rule of rebound intensity and carbonation depth,and establish the related function model,the design of concrete structures for ammonium sulfate erosion environment,construction,maintenance and use to provide the references.The main findings are as follows:(1)By means of a stress loading device,the concrete test block is placed in a stable compressive stress state,immersed in ammonium sulfate solution to the corresponding age,and the effect of stress level and solution concentration on the compressive strength of concrete is found by measuring the ultimate compressive strength of the test block.Based on the test data,the corrosion strength model of concrete is established.The error meets the requirements and has certain universality.The variation of compressive strength of concrete under ammonium sulfate corrosion environment can be calculated and predicted.(2)Alternating test of carbonation and ammonium sulfate corrosion in the stress state of concrete,Starting with the depth of carbonation,To study the effect of stress level and ammonium sulfate solution on the carbonation depth of concrete,By analyzing the variation of carbonation depth,Found that the carbonation depth of 0 to 7 days the fastest growth,Growth slowed 7-14 days,14 to 28 days growth again showed a small increase;The effect of ammonium sulfate solution on concrete is "carbonized ",At the same age,the depth of carbonation increases with the increase of ammonium sulfate concentration,decreases with increasing compressive stress ratio.Treatment of carbonation depth and improvement of existing research results,A prediction model of carbonation depth of concrete containing ammonium sulfate and stress coefficient was established,It provides a reference for the design of the minimum protective layer of concrete structure under ammonium sulfate erosion environment.(3)By analyzing the rebound strength,ultimate compressive strength and carbonation depth of concrete under the action of various factors such as carbonation,stress level and ammonium sulfate solution,drawing the trend map of strength change of each cross-age test block,exploring the influence mechanism of stress and ammonium sulfate on the mechanical properties of concrete.three sets of test data are processed and the corresponding functional equations are obtained based on the regression and the corresponding functional equations are obtained,so that the special strength measurement curves of concrete under ammonium sulfate concentration(1%,2.5%,5%)are made,and the strength of concrete structure under alternating carbonation and ammonium sulfate corrosion is calculated and predicted.