粉煤灰复合磷酸镁水泥耐火性能研究  

Investigation of Fire Resistance of Fly Ash Blended Magnesium Phosphate Cement

作　　者：刘飞[1] 潘宝峰[1] 周长俊[1] 王宝民[1] 聂嘉宇 LIU Fei;PAN Bao-feng;ZHOU Chang-jun;WANG Bao-min;NIE Jia-yu(School of Infrastructure Engineering,Dalian University of Technology,Dalian 116024,Liaoning,China)

机构地区：[1]大连理工大学建设工程学院,辽宁大连116024

出　　处：《中国公路学报》2024年第10期26-37,共12页China Journal of Highway and Transport

基　　金：中央高校基本科研业务费专项资金项目(DUT17RC(3)006)。

摘　　要：磷酸镁水泥(Magnesium Phosphate Cement,MPC)是一种可以在常温下快速凝结硬化的高性能胶凝材料,因其具有早期强度高、耐久性能好、黏结性强等诸多优点,目前广泛应用于快速修补领域。粉煤灰(Fly Ash,FA)因其较好的化学稳定性在固体废弃物应用领域被广泛关注。制备一种粉煤灰复合磷酸镁水泥(FA-MPC)并研究其耐火性能,通过XRD、MIP、FT-IR、SEM/EDS、TGA和DSC等试验综合分析高温煅烧后的水化产物变化机理。力学试验结果表明:随着温度升高,FA-MPC的抗压强度先逐渐降低后缓慢上升,在900℃时抗压强度为12.7 MPa。FT-IR结果表明:随着温度的增加,结晶水的特征峰逐渐消失。XRD结果表明:高温煅烧过程中K型鸟粪石(MgKPO_(4)·6H_(2)O,MKP)晶体先逐渐失去结晶水;在300℃后从晶态转变为非晶态,无明显的晶体特征峰;在600℃后FA-MPC中出现以MgKPO_(4)为主要晶体结构的体系。通过MIP试验发现:随着水化产物从晶态变为非晶态,最终形成晶态的过程中,体系的孔隙结构发生较大变化,最终伴随着MgKPO_(4)晶体的生成,使得孔隙结构致密,进一步提高了FA-MPC的抗压强度。TGA结果表明:600℃高温煅烧后FA-MPC失重率约为1.1%,说明此时已经形成稳定的体系。DSC结果进一步表明:非晶态水化产物出现在427℃左右。Magnesium phosphate cement(MPC)is a high-performance cementitious material that sets and hardens rapidly at room temperature.It is widely used for rapid repairs because of its high early strength,good durability,and strong bonding.Fly ash(FA)is often investigated in studies on solid waste applications because of its good chemical stability.In this study,the fire resistance properties of prepared FA blended magnesium phosphate cement(FA-MPC)were studied.The hydration product mechanism after high-temperature calcination was comprehensively analyzed using XRD,MIP,FT-IR,SEM/EDS,TGA,and DSC tests.The mechanical test results showed that with an increase in temperature,the compressive strength gradually decreased and then slowly increased.The compressive strength was 12.7 MPa at 900℃.The FT-IR results showed that the characteristic peak of crystalline water gradually disappeared with an increase in temperature.The XRD results showed that the crystal of K-struvite(MgKPO_(4)·6H_(2)O,MKP)lost crystal water in the process of high-temperature calcination.Then,the hydration products reached an amorphous state after 300℃,with no obvious crystal characteristic peaks.The FA-MPC system with MgKPO_(4) as the main crystal structure appeared in the FA-MPC after 600℃.The MIP test showed that the pore structure of the system changed significantly as the hydration product changed from a crystalline state to an amorphous state and finally reached a crystalline state.Finally,with the formation of the MgKPO_(4) crystal,the pore structure was compact,and the compressive strength of the FA-MPC was further improved.The thermogravimetric analysis results showed that the weight loss rate of the FA-MPC was approximately 1.1%after high-temperature calcination at 600℃,indicating that a stable system was formed at this time.The DSC results further showed that amorphous hydration products appeared at approximately 427℃.

关 键 词：路面工程 磷酸镁水泥 耐火性能 水化产物 抗压强度 

分 类 号：U416.2[交通运输工程—道路与铁道工程]