摘要
硅灰是制备超高强水泥基材料重要的组成材料,其对极低水胶比体系水化产物及微结构形成影响显著。硅灰的掺量及特性显著影响极低水胶比体系浆体的新拌性能,硅灰掺量过高或颗粒尺寸较小时,浆液新拌性能迅速劣化、力学性能降低,在无有效分散手段下硅灰的掺量不宜超过25%。硅灰掺量增加水泥水化程度逐渐增加,但其二次水化程度逐渐降低;硅灰的二次水化反应与硅灰中活性组分的含量以及颗粒尺寸有关,二氧化硅含量越高硅灰参与二次水化反应程度越高,而硅灰颗粒尺寸相对越大,其在浆液中越容易分散,亦能充分发挥滚珠效应和微填充效应,进而更有利于极低水胶比体系基体的水化反应。基体的力学性能与浆液新拌状态、水化反应进程以及微结构形成三者紧密相关却又非单调变化,较高的硅灰反应活性再叠加优异的分散性更有利于促进水泥的水化反应过程,但在基体相对致密的情况下大量低模量水化产物的形成反而对基体力学性能提升不利,而基体较低的内部缺陷更易实现力学影响的提升,但其只是实现超高强力学指标的必要条件,基体力学性能提升是三者相互作用的结果。
Silica fume is an important component material for the preparation of ultra-high strength cement-based materials.It has a significant effect on the hydration products and microstructure of very low water binder ratio system.The content and characteristics of silica fume significantly affect the fresh mixing performance of slurry with very low water binder ratio.If the content of silica fume is too high or the particle size is small,the fresh mixing performance of slurry will deteriorate rapidly and the mechanical properties will be reduced.Without effective dispersion means,the content of silica fume should not exceed 25%.With the increase of silica fume content,the hydration degree of cement increases gradually,but the secondary hydration degree of silica fume decreases gradually;The secondary hydration reaction of silica fume is related to the content of active components and particle size in silica fume.The higher the silica content of silica fume,the higher the degree of secondary hydration reaction.The larger the particle size of silica fume,the easier it is to disperse in the slurry,and can give full play to the ball effect and micro filling effect,which is more conducive to the hydration reaction of the matrix of the system with very low water binder ratio.The mechanical properties of the matrix are closely related to the fresh state of the slurry,the hydration reaction process and the formation of microstructure,but do not change monotonically.Higher silica fume reaction activity combined with excellent dispersion is more conducive to promote the hydration reaction process of cement.However,when the matrix is relatively dense,the formation of a large number of low modulus hydration products is unfavorable to the improvement of the mechanical properties of the matrix,and the internal defects of the matrix are easier to improve the mechanical influence,but it is only a necessary condition to realize the ultra-high strength mechanical index.The improvement of matrix mechanical properties is the result of the interaction of high reactivity,excellent dispersion and low internal defects.
作者
夏中升
沙建芳
郭飞
刘建忠
韩方玉
XIA Zhongsheng;SHA Jianfang;GUO Fei;LIU Jianzhong;HAN Fangyu(Jiangsu Sobute New Materials Co.,Ltd.,Nanjing 211103,China;State Key Laboratory of High Performance Civil Engineering Materials,Nanjing 211103,China)
出处
《混凝土》
CAS
北大核心
2023年第12期102-107,114,共7页
Concrete
基金
国家自然科学基金面上基金(51978318)
国家自然科学基金青年基金(52008191)。
关键词
硅灰
极低水胶比
水化产物
微结构
silica fume
extremely low water-binder ratio
hydration products
microstructure
