不同养护方式对铁尾矿砂制备的再生粗骨料性能影响

Effects of different curing methods on the properties of recycled coarse aggregate prepared from iron tailings sand

为了提高铁尾矿沙的利用率,本文采用成球技术使用铁尾矿沙制备粗骨料,将经过界面预处理后的铁尾矿砂采用喷洒预处理液水雾,同时撒入胶凝材料的方式生成骨料颗粒,最后将骨料颗粒进行养护得到再生粗骨料。探究不同的养护方式对再生粗骨料的性能的影响,结合SEM和MIP探究养护方式对再生粗骨料微观形貌和孔结构的影响。结果表明:改进的成球技术制备铁尾矿沙再生粗骨料具有一定的可行性。另外,自然养护条件骨料的性能表现最差,蒸汽养护骨料的压碎指标最小,碳化养护骨料的吸水率最小。从微观结构来看碳化养护的骨料体系结构致密,孔隙和微裂缝含量相对较少,因此骨料吸水率最小;蒸汽养护水化产物含有大量的凝胶状和网状结构的水化硅酸钙、针状钙矾石和少量的氢氧化钙晶体,这是压碎指标小的原因。这些研究结果为铁尾矿沙制备再生粗骨料应用于混凝土的后期服役过程中提供了指导意义。

To improve the utilization rate,the pelletizing technology was adopted to prepare coarse aggregate from iron tailings sand.The iron tailings sand,after interface pretreatment,was sprayed with a pretreatment liquid of water mist,which was mixed with cementitious materials to generate aggregate particles.Finally,the aggregate particles were cured to obtain recycled coarse aggregate.Moreover,the effects of different curing methods on the properties of recycled coarse aggregate were explored,and the effect of curing methods on the micromorphology and pore structure of recycled coarse aggregate was additionally explored by combining SEM and MIP.Results showed the feasibility of using the improved pelletizing technology to prepare recycled coarse aggregate of iron tailings sand.Moreover,the performance of aggregates under natural curing conditions was the worst,the crushing index of steam curing aggregates was the smallest,and the water absorption of carbonated curing aggregates was the smallest.In terms of microstructure,the aggregate system cured by carbonization had a dense structure,relatively few pores,and microcracks.Therefore,the water absorption of aggregate was the smallest;the hydration product of steam curing contained a large amount of calcium silicate hydrate with gelatinous and netlike structures,needle-like ettringite,and a small amount of calcium hydroxide crystals;The crushing index was small.These findings guide the preparation of recycled coarse aggregate from iron tailings sand and its application in the subsequent service of concrete.