摘要
为探索大流动性高强轻集料混凝土约束收缩特性及抗裂性能,试验采用高强页岩陶粒制备大流动性高强轻集料混凝土(HSLC),测试其基本力学性能,通过外侧面干燥条件下的圆环约束收缩试验,研究高强轻集料混凝土约束收缩开裂性能。研究结果表明:HSLC与普通混凝土(NC)比较,HSLC在7 d前的收缩应变量及应变增长率明显高于NC,7 d后LC收缩应变增长减缓,开裂时HSLC总收缩应变明显小于NC;掺加粉煤灰可以提高混凝土的流动性、减小HSLC的收缩,但粉煤灰掺量应小于25%;硅灰复掺虽对提高HSLC强度有利,但显著增加混凝土收缩变形;与相同强度等级的NC比较,HSLC早期开裂风险系数较小,但从混凝土承载能力的角度NC的抗裂性能要优于HSLC;粉煤灰能降低混凝土约束收缩下的开裂风险;粉煤灰与硅粉复掺的混凝土早期开裂风险明显大于单掺粉煤灰的混凝土;轻集料预湿能对增强HSLC的抗裂性能非常有利。
In order to explore the constrained shrinkage and crack resistance of high workability and high strength lightweight aggregate concrete(HSLC),high strength shale ceramsite,fly ash and silica fume were used to prepare HSLC with good performance,to test its basic mechanical properties and to study the restrained shrinkage cracking behavior of HSLC through the ring-constrained shrinkage test under the dry condition of the outer surface.The experimental results show that:Compared with normal concrete(NC),the shrinkage strain and strain growth rate of HSLC during the first 7 days are obviously higher than those of NC.After 7 days,the shrinkage strain growth of HSLC slows down,and the total shrinkage strain of HSLC during cracking is obviously smaller than that of normal concrete.Fly ash can obviously improve the performance of fresh HSLC paste and reduce the shrinkage strain of HSLC,but its content should be controlled within 25%.Silica fume composite,beneficial to the improvement of the strength of HSLC,can significantly increase the shrinkage deformation of concrete.Compared with NC of the same strength grade,HSLC has smaller risk factor of early cracking,but its cracking resistance is better than HSLC from the point of bearing capacity of concrete.Fly ash alone can reduce the cracking risk factor of confined shrinkage of concrete.The risk factor of early cracking of concrete mixed with fly ash and silica fume is obviously greater than that of concrete with fly ash alone.The pre-wetting of soil and lightweight aggregate can greatly improve the crack resistance of concrete.
作者
张登祥
蒋晓明
ZHANG Dengxiang;JIANG Xiaoming(School of Hydraulic Engineering,Changsha University of Science and Technology,Changsha 410114,China)
出处
《铁道学报》
EI
CAS
CSCD
北大核心
2021年第5期190-196,共7页
Journal of the China Railway Society
基金
湖南省自然科学基金(2017JJ2273)。
