摘要
目前采用的喷射混凝土黏结强度较低,在施工后的初始阶段无法满足支护强度的要求.因此通过引入硅灰、微珠、纤维素以及早强减缩剂探究不同复合胶凝材料的力学性能及水化热反应特性.基于Krstulovic-Dabic水化动力学模型开展复合胶凝材料水化过程研究,通过联合喷射混凝土早龄期抗压强度及劈裂强度分析其力学发展规律.结果表明:硅灰及早强减缩剂对混凝土早期力学强度均有显著提高作用,而纤维素及微珠对强度有降低作用;各工况下复合胶凝体系的水化动力学过程为结晶成核与晶体生长(NG)、相边界反应(I)和扩散(D)3个阶段;硅灰掺量的增加会增高溶解峰高度 20.4%且提前反应峰出现时间 22.2%;纤维素的掺加显著提高了溶解峰强度但降低了反应峰高度.
Abstract
The bonding strength of sprayed concrete currently used is relatively low,and it cannot meet the requirements for support strength in the initial stage after construction.Therefore,it explores the mechanical properties and hydration heat reaction characteristics of different composite cementitious materials by introducing silica fume,ceosphere,cellulose,and accelerator.Based on the Krstulovic-Dabic hydration kinetics model,the hydration process of composite cementitious materials was studied.The mechanical development law of the combined sprayed concrete was analyzed through the early age compressive strength and splitting strength.The results show that silica fume and accelerator have a significant effect on improving the early mechanical strength of concrete,while cellulose and ceosphere have a reducing effect on the strength.The hydration kinetics process of the composite cementitious system under various operating conditions consists of three stages,crystallization nucleation and crystal growth(NG),phase boundary reaction(I)and diffusion(D).The increase of silica fume content will increase the height of the dissolution peak by 20.4%and the occurrence time of the early reaction peak by 22.2%.The addition of cellulose significantly increased the dissolution peak intensity but reduced the reaction peak height.
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