Zou Meng, He Zhaoyi, Xia Yuhua, Li Qinghai, Yao Qiwen, Cao Dongwei
School of Civil Engineering, Chongqing Jiaotong University, Chongqing 400074, China.
School of Traffic and Transportation, Chongqing Jiaotong University, Chongqing 400074, China.
Materials (Basel). 2024 Dec 19;17(24):6201. doi: 10.3390/ma17246201.
This study investigated the potential for efficient and resourceful utilization of phosphogypsum (PG) through the preparation of a High-volume Phosphogypsum Cement Stabilized Road Base (HPG-CSSB). The investigation analyzed the unconfined compressive strength (UCS), water stability, strength formation mechanism, microstructure, and pollutant curing mechanism of HPG-CSSB by laser diffraction methods (LD), X-ray diffraction (XRD), fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and inductively coupled plasma-mass spectrometry (ICP-MS). The optimal mix ratio of HPG-CSSB was 4% cement, 1% CA2, 35% PG, and 60% graded crushed stone. The UCS reached 6.6 MPa, 9.3 MPa, and 11.3 MPa at 7, 28, and 60 d, respectively. The alkaline curing agent stimulated cement activity and accelerated the release of Ca and SO from the PG. This formed many C-S-H gels and ettringite (AFt). The curing agent converted Ca to C-(A)-S-H gels due to high volcanic ash activity. The diverse hydration products strengthened HPG-CSSB. The HPG-CSSB exhibits favorable water stability, demonstrating a mere 7.6% reduction in strength following 28 d of immersion. The C-S-H gel and AFt generated in the system can carry out ion exchange and adsorption precipitation with F and PO in PG, achieving the curing effect of toxic and hazardous substances. HPG-CSSB meets the Class A standard for integrated wastewater discharge.
本研究通过制备高掺量磷石膏水泥稳定道路基层（HPG-CSSB），探讨了磷石膏（PG）高效且资源节约型利用的潜力。该研究采用激光衍射法（LD）、X射线衍射（XRD）、傅里叶变换红外光谱（FTIR）、扫描电子显微镜（SEM）、能量色散X射线光谱（EDS）和电感耦合等离子体质谱（ICP-MS），分析了HPG-CSSB的无侧限抗压强度（UCS）、水稳定性、强度形成机制、微观结构及污染物固化机制。HPG-CSSB的最佳配合比为4%水泥、1% CA2、35% PG和60%级配碎石。在7、28和60 d时，UCS分别达到6.6 MPa、9.3 MPa和11.3 MPa。碱性固化剂激发了水泥活性，加速了PG中Ca和SO的释放。这形成了许多C-S-H凝胶和钙矾石（AFt）。由于火山灰活性高，固化剂将Ca转化为C-(A)-S-H凝胶。多样的水化产物增强了HPG-CSSB。HPG-CSSB表现出良好的水稳定性，浸泡28 d后强度仅降低7.6%。体系中生成的C-S-H凝胶和AFt可与PG中的F和PO进行离子交换和吸附沉淀，实现有毒有害物质的固化效果。HPG-CSSB满足综合废水排放的A类标准。
