氢氧化镁对过期水泥的改良研究  

Improvement of expired cement by magnesium hydroxide

作　　者：杨圳华 王超林 YANG Zhenhua;WANG Chaolin(School of Civil Engineering,Guizhou University,Guiyang 550025,China;Key Laboratory of Geomechanics and Engineering Safety of Guizhou Province,Guiyang 550025,China)

机构地区：[1]贵州大学土木工程学院,贵州贵阳550025 [2]贵州省岩土力学与工程安全重点实验室,贵州贵阳550025

出　　处：《混凝土》2022年第10期188-192,共5页Concrete

基　　金：国家自然科学基金(52004072);贵州省省级科技计划项目资助([2020]4Y044,[2020]2004)。

摘　　要：采用Mg(OH)_(2)以外掺剂的形式与过期复合硅酸盐水泥混合制备成水泥胶砂试件,利用Mg(OH)_(2)部分溶于水时完全电离为Mg^(2+)和OH^(-),掺加在水泥中既可以碱激发水泥和未溶于水的部分充当惰性骨料的共同作用下,研究其力学强度和微观结构变化,为过期水泥的再利用提供一种行之有效的方法。结果表明:Mg(OH)_(2)可有效激发过期水泥水化反应,填充密实结构,提高抗压强度,但脆性也会相应提高;掺入Mg(OH)_(2)的过期水泥胶砂试件水化产生了大量的C-S-H凝胶联合骨料颗粒连接成整体,孔隙率降低,结构密实,但在超过最佳掺量后会因为过多的骨料颗粒和相应不足的C-S-H凝胶而发生强度略微下降,且有强度低的Ca(OH)_(2)晶体析出。The cement mortar specimens were prepared by mixing Mg(OH)_(2) as an admixture with expired composite Portland cement.When Mg(OH)_(2) was partially dissolved in water,it was completely ionized into Mg^(2+) and OH^(-),and added under the combined effect of the alkali-activated cement and the insoluble part of the cement as the inert aggregate,the mechanical strength and microstructure changes of the cement can be studied.The results show that Mg(OH)_(2) can effectively stimulate the hydration reaction of expired cement,fill the dense structure,improve the compressive strength,but the brittleness will also increase correspondingly.The expired cement mortar sample mixed with Mg(OH)_(2) produces a large amount of the CSH gel and aggregate particles are connected into a whole,the porosity is reduced,and the structure is dense.However,after exceeding the optimal content,the strength will slightly decrease due to the excessive aggregate particles and the corresponding insufficient CSH gel,and there is Ca(OH)_(2)crystals with low strength are precipitated.

关 键 词：过期水泥 碱激发 力学 填充 SEM 声发射 

分 类 号：TU528.01[建筑科学—建筑技术科学]