磨细矿物掺合料对水泥硬化浆体孔结构及砂浆强度的影响

采用压汞法研究了钢渣、矿渣、粉煤灰单掺或复掺对水泥硬化浆体孔结构的影响.同时还研究了掺合料单掺或复掺对水泥砂浆抗压强度的影响.结果表明:掺合料单掺或复掺对早期水泥硬化浆体的孔结构有一定的劣化作用;水化后期,矿渣与钢渣均明显降低了水泥硬化浆体的孔隙率,矿渣与粉煤灰均明显降低了水泥硬化浆体的中值孔径并改善了水泥石的孔径分布,掺合料复掺对改善水泥硬化浆体的孔结构有积极作用,尤其是掺合料三元复合可取得最佳的效果.3种掺合料降低水泥硬化浆体孔隙率能力的大小顺序为:矿渣>钢渣>粉煤灰.3种掺合料降低水泥硬化浆体孔径并改善孔径分布能力的大小顺序为:矿渣>粉煤灰>钢渣.掺合料降低了水泥砂浆早期的抗压强度,却增加了水泥砂浆90 d的抗压强度.掺合料的活性大小顺序为:矿渣>钢渣>粉煤灰.

INFLUENCE OF GROUND MINERAL ADMIXTURES ON PORE STRUCTURE OF HARDENED CEMENT PASTE AND STRENGTH OF CEMENT MORTAR

The influence of singly and compositely adding steel slag, blast furnace slag and fly ash on the pore structure of handened cement paste was studied using mercury intrusion porosimetry (MIP). Furthermore, their influence on the compressive strength of cement mortar was also investigated. The results show that the pore structure of cement paste become worse at early ages by singly or compositely adding any of the mineral admixtures. At later ages, adding either blast furnace slag or steel slag remarkably reduces the porosity of cement paste, while either blast furnace slag or fly ash remarkably reduces median pore diameter and improves pore size distribution. The most reduction in the porosity of cement paste is observed for the cement with blast furnace slag, while the cement with steel slag less, and the cement with fly ash the least. The biggest improvement on pore structure is observed for the cement with blast furnace slag, while the cement with fly ash smaller, and the cement with steel slag the smallest. Pore structure of cement paste can be improved by compositely adding these three types of mineral admixtures at later ages, while the best result is achieved by compositely adding three mineral admixtures. The study also shows that mineral admixtures reduce the compressive strength of cement mortar at early ages, but enhance it at 90 d . Blast furnace slag showed the highest activity, while steel slag lower and fly ash the lowest.