摘   要：磷石膏是生产工业磷酸等的副产物，通常，磷石膏在水泥水化硬化中可起缓凝作用。本文基于低场核磁共振法这一无损检测方法，研究磷石膏的掺入对水泥在水化硬化过程中引起的早期孔结构的变化。结果表明，随着磷石膏的加入，水泥硬化体中的孔径分布逐渐向较小尺寸的方向进行发展；水泥硬化体的最可几半径不仅随养护龄期的增加而逐渐降低，随磷石膏掺量的增加而逐渐增加。基于分形理论研究了在该过程中水泥硬化体的孔径分布的变化，结果表明，其分形维数随养护龄期的增加而逐渐降低，随磷石膏掺量的增加而逐渐降低。

Abstract: Phosphogypsum is a by-product of the production of industrial phosphoric acid. Generally speaking, phosphogypsum plays a retardation role in hydration and hardening of cement. A new nondestructive testing method based on low field nuclear magnetic resonance (NMR) method was used to study the changes of pore structure in the early stage caused by the incorporation of phosphogypsum on cement in the process of hydration and hardening. The results show that with the addition of phosphogypsum, the pore size distribution of hardened cement gradually developed to a smaller size. The most probable radius of hardened cement paste decreases with the increase of curing age and increased with the increase of phosphogypsum content. Based on the fractal theory, the variation of the pore size distribution of the hardened cement paste in this process is studied. The results show that the fractal dimension decreased gradually with the increase of curing age, and gradually decreases with the increase of the amount of phosphogypsum.