氯盐侵蚀环境下膏体充填体稳定性试验研究

Experimental study of stability of paste backfill under chloride erosion environment

为了研究矿井水对膏体充填体稳定性的影响,制备了质量分数为0,5%,10%,15%的氯盐溶液,进行了为期30,60,90,120 d的膏体充填体试样氯盐溶液侵蚀试验,研究了氯盐溶液对膏体充填体宏观性能和微观结构的劣化效应.研究结果表明:质量分数为0,5%,10%,15%氯盐溶液中的膏体充填体试样质量变化率整体呈递增的趋势,但随着侵蚀龄期的增加,试样内部膨胀性水化产物的溶出和分解程度增大,质量变化率增幅减小.随着侵蚀龄期的增加,试样单轴抗压强度先增加后降低,最后趋于稳定;当浸泡30 d时,与无氯盐溶液中的试样相比,质量分数为5%,10%,15%氯盐溶液中的试样单轴抗压强度分别提高了0.74,0.57,0.37 MPa,这主要是因为试样内发生了二次水化反应生成了弗里德尔盐(Friedel’s盐)而填充了其内部孔隙,提高了试样致密性和宏观强度;但当浸泡120 d时,氯盐溶液中的试样内部生成了更多的Friedel’s盐导致结晶膨胀压力增大,加剧了试样内部损伤,降低了宏观强度;与无氯盐溶液中的试样相比,其单轴抗压强度分别降低了0.17,0.25,0.58 MPa.

In order to study the influence of mine water on the stability of paste backfill,0,5%,10%and 15%chloride solution were prepared,the erosion tests of samples immersed in chloride solution were carried out for 30,60,90,120 d.The deterioration effect of chloride solution on the macro properties and microstructure of paste backfill were studied.The results show that the mass change rate of paste backfill samples immersed in 0,5%,10%,15%chloride solution is increased.However,with the increase of corrosion age,the dissolution and decomposition degree of expansive hydration products in the sample is increased,resulting in the decrease of mass change rate.With the increase of erosion age,the uniaxial compressive strength of the samples increases firstly,then decreases,and finally tends to be stable.When the samples are immersed in 5%,10%,15%chloride solution for 30 d,the uniaxial compressive strength is increased by 0.74,0.57 and 0.37 MPa,respectively,compared with the samples without chloride solution.This is mainly due to the formation of Friedel’s salt in the secondary hydration reaction in the sample,which fills the internal pores and improves the compactness and macro strength of the sample.However,more Friedel’s salt is formed in the sample immersed in chloride solution for 120 d,which increases the crystallization expansion pressure,aggravated the internal damage and reduces the macro strength of the sample.Compared with the samples in the chlorine free solution,the uniaxial compressive strength of the samples immersed in 5%,10%and 15%chloride solution is decreased by 0.17,0.25 and 0.58 MPa,respectively.