微胶囊在修补砂浆中延迟释放早强剂的应用及性能分析

Microcapsules for Realizing Delayed Release of Early Strength Agent in Repair Mortar and Their Property Analysis

为使修补砂浆具备合适的凝结时间和较高的早期强度,将无水硫酸钠经微胶囊包覆后掺入到修补砂浆中,进而研究微胶囊对修补砂浆凝结时间、抗压强度、水化进程、水化产物以及水化早期钙矾石生长速率的影响。结果表明,微胶囊的掺入显著延长了浆体的凝结时间,缩短了其初凝、终凝的时间间隔,且对砂浆的早期强度无明显影响;使浆体的水化速度在开始的3 h内处于一个较低的水平,随后其水化速度增大,并最终与掺等量无水硫酸钠浆体的水化程度达到相当水平。另外,掺微胶囊的浆体早期钙矾石的生长速率处在一个较高的水平,且水化4 h后能达到与掺等量无水硫酸钠体水化产物相当的致密度。

Aiming at preparing a kind of repair mortar with proper setting time and higher early strength,anhydrous sodium sulfate was microencapsulated and incorporated into the repair mortar.Then the effects of the microcapsules on setting time,compressive strength,development of hydration process,hydration product and the growth rate of ettringite in early hydration of the repair mortar were investigated in depth.The results showed that the setting process of paste was substantially prolonged,the interval of initial and final setting time was shortened,while no obviously variation of compressive strength was found after the anhydrous sodium sulfate microcapsules were incorporated in the repair mortar.Thanks to the addition of the microcapsules,the hydration rate of the paste maintained at a low level in the first 3 h of hydration,then the hydration rate increased obviously,and finally the paste reached the similar hydration degree with the repair mortar adding the same amount of anhydrous sodium sulfate.Besides,the repair mortar with microcapsules exhibited a high growth rate of ettringite in early hydration,and its hydration product could obtain a similar densification with that of the repair mortar adding the same amount of anhydrous sodium sulfate after hydration for 4 h.