缓释型硅酸钠微胶囊的制备及其对砂浆孔隙率的影响  

Preparation of sustained release sodium silicate microcapsule and its effect on porosity of mortar

作　　者：李中航 王金玉 肖悦 张帆 王秦伟 但建明[1] LI Zhonghang;WANG Jinyu;XIAO Yue;ZHANG Fan;WANG Qinwei;DAN Jianming(Key Laboratory for Green Processing of Chemical Engineering of Xinjiang Bingtuan,School of Chemistry and Chemical Engineering,Engineering Research Center of Materials-Oriented Chemical Engineering of Xinjiang Production and Construction Corps Key Laboratory of Materials-Oriented Chemical Engineering of Xinjiang Uygur Autonomous Region,Shihezi 832003,China)

机构地区：[1]新疆兵团化工绿色过程重点实验室/省部共建国家重点实验室培育基地材料化工新疆维吾尔自治区重点实验室,新疆石河子832003

出　　处：《混凝土》2023年第3期135-140,共6页Concrete

基　　金：国家自然科学基金(51368053)。

摘　　要：为保障硅酸钠内掺后能在水泥基材料固化成型后发挥结晶反应修复孔隙和裂缝的作用,使用乙基纤维素(EC)包覆二氧化硅含量高的高模数硅酸钠制得缓释型硅酸钠微胶囊,并在成型时内掺到砂浆中。利用SEM、FTIR及UV-VIS分光光度计探究微胶囊的形态、包覆效果及缓释行为。以吸水率、力学强度以及孔隙率为考察指标,并结合TG、XRD分析等探究微胶囊对砂浆内部孔隙及裂缝的修复作用及反应机理。试验结果表明,经EC包覆后的硅酸钠表面粗糙,缓释效果随壁芯比的升高而提升;取0.7 g乙基纤维素,3.5 g硅酸钠为最佳制备条件,硅酸钠释放量最高降低75%;当微胶囊掺量为5%,修复时间达21 d时,孔隙率降低8.92%,吸水率降低29.67%,抗压强度提高12.37%。机理分析表明缓释型硅酸钠微胶囊内掺后会与氢氧化钙反应生成水化硅酸钙,从而能在一定程度上堵塞孔隙和裂缝,降低砂浆孔隙率。To ensure that sodium silicate can play the role of crystallization reaction to repair pores and cracks after cement-based materials are solidified,ethyl cellulose(EC)is used to coat high modulus sodium silicate with high silica content to prepare sustained release sodium silicate microcapsules,which are mixed into mortar during molding.Water absorption,mechanical strength and porosity were used to examine the effect of the repair,combined with TG analysis and XRD analysis,the repair effect and reaction mechanism of microcapsules on the internal pores and cracks of mortar were explored.The results indicated that after being encapsulated by EC,sodium silicate exhibited a rougher surface,and the sustained-release effect improved with the increase of the wall core ratio.Taking 0.7 g ethyl cellulose and 3.5 g sodium silicate as the optimal process condition,the release of sodium silicate can be reduced by up to 75%.When the content of microcapsules was 5%and the repair time was 21 d,the water absorption of mortar mixed with microcapsules decreased by 29.67%,the compressive strength increased by 12.37%,and the porosity decreased by 8.92%.The mechanism analysis indicate that the sustained sodium silicate microcapsules will react with calcium hydroxide to form calcium silicate hydrate,which can block pores and cracks to a certain extent and reduce the porosity of the mortar.

关 键 词：微胶囊 硅酸钠 缓释性能 砂浆 孔隙 渗透结晶反应 

分 类 号：TU528.01[建筑科学—建筑技术科学]