| Alkali-slag material is a new type of cementitious material with great research value and great potential.It is expected to replace traditional Portland cement as a new building material,and has a long-term significance for improving environmental problems and realizing sustainable green development.This paper in view of the hot research direction of the alkali-slag cementing materials--early shrinkage of concrete is studied,will be applied widely in alkali-slag of superabsorbent resin,by the way of curingto improve the alkali slag concrete early age shrinkage(drying shrinkage and autogenous shrinkage)as a research starting point,so as to promote the popularization and application of alkalislag materials.The specific research contents and conclusions are as follows:(1)In this paper,the fineness(A,B,C,D four kinds of fineness)of superabsorbent resin and the resin content(0,0.2%,0.4%,0.6%)were used as variables,A total of 13 groups,the water binder ratio of 0.45 of the alkali-slag pure slurry specimen,The autoshrinkage,drying shrinkage,specimen strength and basic properties were studied,and the deep reasons of shrinkage reduction were analyzed by microscopic tests(MIP mercury injection test and SEM electron microscope test).(2)The absorbability of four kinds of fineness resins in deionized water,tap water and alkali excited solution was tested.The results showed that the smaller the fineness of the resin was,the faster the absorbance rate was,and the fineness had little effect on the saturation absorbance rate.It was found that the faster the suction rate of the resin was,the more obvious the inhibition effect on shrinkage was.(3)As for shrinkage,resin addition can effectively improve the shrinkage property of alkali-slag material,and the shrinkage gradually decreases with the increase of resin content and the decrease of fineness.The study found that the addition of resin can effectively reduce the shrinkage,0.2% resin content,28 days of drying shrinkage decreased by 32%;The corrugated tube method showed that the autocontraction decreased by 64.4% at 7 days.(4)The addition of resin will reduce the strength of alkali-slag specimen,and it decreases with the increase of resin content and the decrease of fineness,and has a great influence on the strength of early age specimen.With the increase of age,the gap gradually shrinks.Compared with G-0,experimental group D,D-2,D-4 and D-6 had the best contractile inhibition,and the 28 d flexural strength decreased by 7.3%,12.7% and21.8% respectively,and the 28 d compressive strength decreased by 8.5%,19% and 30.9%respectively.(5)As for the basic properties of alkali-slag material,the addition of 0.2% resin will not have too much influence on its fluidity,condensation test piece and water absorption rate,which can meet the requirements of national specifications.(6)Through microscopic tests,it is found that the addition of superabsorbent resin can reduce the porosity of alkali-slag material,and the porosity gradually decreases with the increase of the content.The addition of resin can improve the pore distribution of alkali slag material,and make the content of capillary pores(5-20nm)decreased,and the number of macropores increased,so as to reduce the surface tension of capillary pores.From the perspective of shrinkage control,comparing the results of resin and other test data,we can get that the optimal resin content is about 0.2%,and the optimal fineness is D type resin. |
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