Influence of nanosized magnesia on the hydration of borehole-sealing cements prepared using different methods  

作　　者：Quanle Zou Jinfei Zhan Xin Wang Zhen Huang 

机构地区：[1]State Key Laboratory of Coal Mine Disaster Dynamics and Control,School of Resources and Safety Engineering,Chongqing University,Chongqing 400044,China

出　　处：《International Journal of Coal Science & Technology》2023年第4期343-360,共18页国际煤炭科学技术学报（英文）

基　　金：supported by“Overall Rationing System”Project of Chongqing Talent Program(cstc2022ycjh-bgzxm0077);the National Natural Science Foundation of China(52074041);Natural Science Foundation of Chongqing,China(cstc2020jcyj-msxmX0836);Fundamental Research Funds for the Central Universities(2020CDJ-LHZZ-002),which are gratefully acknowledged.

摘　　要：Gas drainage is an efective technology for gas control in coal mines.A high borehole-sealing quality is the fundamental precondition for efcient gas drainage.The expansibilities of cement pastes used in borehole-sealing processes are critical for the borehole-sealing efect.Nanosized magnesia expansive agents are used to improve the expansibilities of cement pastes and improve the borehole-sealing efect.Nuclear magnetic resonance spectrometry and scanning electron microscopy were adopted to study the efects of nanosized magnesia on the hydration of borehole-sealing cements used with diferent preparation methods.The results showed that an increase in the mass fraction of the nanosized magnesia promoted cement hydration,and the mass fraction was positively correlated with the promotion efect.The use of diferent preparation methods did not change the water-phase distribution in the cement.When using the wet-mixing preparation method,nanosized magnesia promoted the induction,acceleration,and deceleration periods of hydration;when using the dry-mixing preparation method,the nanosized magnesia promoted the induction period of cement hydration,and the promotion efect was less obvious than that seen when using the wet-mixing method.When using the wet-mixing preparation method,the nanosized magnesia was uniformly dispersed,thus enlarging the surface area of the reaction,which provided more nucleation sites for the hydration products of the cement and therefore accelerated the hydration reaction.When using the dry-mixing preparation method,the nanosized magnesia powders were dispersed nonuniformly and aggregated.Under these conditions,only a few nanosized magnesia particles on the surfaces of the aggregated clusters took part in hydration,so only a small number of nucleation sites were provided for the hydration products of cement.This led to inconsistent hydration of cement pastes prepared using the dry-mixing method.The surface porosity of the cement prepared with the wet-mixing preparation method frst decreased and then

关 键 词：Borehole-sealing cement Nanosized magnesia Preparation method HYDRATION Morphological analysis Nuclear magnetic resonance relaxation analysis 

分 类 号：TE37[石油与天然气工程—油气田开发工程] TD82[矿业工程—煤矿开采] TP18[矿业工程—矿山开采]