磷石膏激发预处理及其制备免烧建材的研究

Excitation Pretreatment of Phosphogypsum and Preparation of Non-Burning Building Materials

磷石膏胶凝活性差,阻碍了它在建材领域的大宗消纳。本文通过研究碱激发预处理后磷石膏物相和微观结构,以及用其制备高掺量免烧建材的抗压强度、物相和微观结构,从而获得磷石膏制备高掺量、高抗压强度免烧建材的工艺参数。结果表明:100 g磷石膏,碱激发剂为100 mL,在室温下预处理24 h后,磷石膏主晶相CaSO 4·2H 2O的晶粒变小,结晶度降低,通过观察微观结构发现硫酸钙颗粒变大,细小颗粒量大幅降低,从而提高了其胶凝活性。当磷石膏掺入量为80%(质量分数)时,与未处理磷石膏相比,所制备的免烧建材保养7 d、28 d和浸水后的抗压强度均明显提高,分别为13.79 MPa、18.22 MPa和11.44 MPa,其微观形貌显示硫酸钙颗粒间没明显边界,几乎融为一体,致密度极高,对材料强度的增加十分有利。

Phosphogypsum has poor cementitious activity,which hinders its large consumption in the field of building materials.By studying the phase and microstructure of phosphogypsum pretreated by alkali excitation,and the compressive strength,phase and microstructure of the non-burning building materials prepared with the high content phosphogypsum,the process parameters of preparing high content and high compressive strength non-burning building materials with phosphogypsum were obtained.The result shows that,when 100 g phosphogypsum is added with 100 mL activator,after 24 h of excitation under room temperature,the main crystalline phase CaSO 4·2H 2O of phosphogypsum has smaller grains and lower crystallinity.Microstructure analysis shows that the size of calcium sulfate particles increases and the amount of fine particles decreases significantly after pretreatment.Thus,its gelation activity is improved.When the content of phosphogypsum is 80%(mass fraction),compared with the untreated phosphogypsum,the compressive strength of the prepared non-burning building materials after maintening for 7 d,28 d and immersion in water are significantly improved,which are 13.79 MPa,18.22 MPa and 11.44 MPa,respectively.Its micromorphology shows that there is no obvious boundary between the calcium sulfate particles,they are almost integrated with high density,which is very beneficial to the strength of the materials.