Qun Pan;Changhui Yang;Lin Liu;
<正>As an environment friendly material,alkali-activated slag cement receives a great deal of attention due to rapid development of early-age strength and high resistance against aggressive ions,e.g.Cl~-,SO_4~(-2).However,the further application of alkali-activated slag cement was limited by its two distinguishing features,low workability and fast setting, which cannot be solved by commercial admixtures for Ordinary Portland cement.As a result,a new admixture is needed to remove these technical barriers. This study reports a new type compound admixture YP developed for slag cement activated by water glass.The effect of the compound admixture on properties of slag pastes,including mini slump,setting time and heat of hydration was examined.It is found that the slump of slag paste was increased from 60 mm to 120 mm by using the admixture.Furthermore,the initial and final setting times of paste with the admixture were 96 min and 132 min,while it only took 18 min and 23 min to achieve initial setting and final setting for the paste without using the admixture.In addition,the results also indicate that the initial peak was delayed for nearly 7 hours and the heat flow of hydration was reduced from 5864μw/g to 461μw/g,when the admixture was added.It can be concluded that the new admixture is capable of imparting a significant improvement of workability of alkali-activated slag cement with a suitable setting behaviour. Originality Low workability and rapid setting are two main factors limiting the further use of alkali-activated slag cement.This study is intended to solve these two issues by adding an innovative admixture developed at Chongqing University.Based on the results presented,the use of new type admixture is able to improve the workability and to prolong the initial and finial setting time of slag cement activated by water-glass.
compound admixture YP;;slag pastes activated by water glasst;;heat evolution of hydration;;setting time;;mini slump
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