Research On The Reaction Process And Modified Performance Of Alkali-activated Slag Materials

In the era when the construction industry develops rapidly,shortage of resources and environmental pollution have become urgent problems to be solved.In terms of building resources,exploration of new green building materials in line with the current situation has emerged as one of the most important research directions in this field.The alkali-activated slag cement as a kind of environment-friendly resources is made by making full use of waste materials produced in the metallurgical industrial production process and from the perspective of research and development of its long-term application value and market value,it features high tolerance as well as energy and economic efficiency,agreeing with the current idea of pursuing the sustainable development of environment-friendly resources.In the present-day context,the study of the alkali-activated slag materials is not mature,of which the causes mainly lie in two aspects: a)Absence of integrated basic studies on the mechanism of hardening reaction of the alkali-activated slag,leading to insufficiency of referable theoretical knowledge concerning the comprehensive application of the alkali-activated slag materials.b)lack of researches into the ways of optimizing the comprehensive properties of the alkali-activated slag materials based on their characteristics so as to create their wider application values---a problem that calls for immediate consideration and study.Considering the internal factors of alkali activated material reaction,different composite ratio and alkaline excitation environment will change the reaction rate and product structure of the material,resulting in the difference in the performance of the material.Based on the above factors,the effects of water to glue ratio and alkali content on AAS are first explored,including the comprehensive development,trend of product structure,setting time,workability and so on.At the same time,in the course of the study,it was integrated new researches on the electrode resistivity test method and the alkali slag material for the first time,this paper has probed into the relationship between the law of the electrode resistivity development and the hardening of the alkali-activated slag characteristics existing in the hardening reaction process of the alkali-activated slag---the constant changing of the electrode resistivity of the alkali-activated slag was found to be related to the liquid phase ion concentration and porosity and through the linear fitting,the linear relationship between the setting time and resistivity development characteristics points of the alkali-activated slag and that between the compressive strength and the electrical resistivity are revealed.This had provided an innovative idea for studying the changing law of the setting time of the alkali slag and the trend of the development of mechanical strength.In addition,the paper also has made an analysis of the mechanism of the hardening reaction by use of the methods of reaction heat,p H change,pore development and TEM.The comprehensive application of cementitious materials involved the understanding of the reaction mechanism and a good working performance.In its second part,the paper mainly has discussed the modification of the performance of the alkali-activated slag materials,which included the following three perspectives:1?The improvement of autogenous shrinkage of the alkali-activated slag.The improvement of autogenous shrinkage is analyzed by mixing different amounts of metakaolin---it showed that when the mixed amount of metakaolin reached about 30%,the autogenous shrinkage decreased by 38.6%,yielding the best improvement effect.2?The improvement workability of the alkali-activated slag.By adding two kinds of water reducing agents of ADVA100 and Super1000 TK,the improvement of fluidity and viscosity of the alkali slag was analyzed---the experiment showed that the slump fluidity rose from 185.5 mm to 226.5 mm when the dosage of water reducer is 1%,had produced the best improvement effect.3?The improvement of the toughness of the alkali-activated slag.By adding short fiber,polypropylene fiber and polyethylene fiber loaded displacement test and SEM morphology analysis,it can be found that with added fibers,the alkali-activated slag significantly improved its toughness with its flexural strength went upward from 11.5 MPa to 18.5 MPa increased by 60.5%,and its compressive strength ratio changed downward from 10.975 to 5.986.