Calcareous sands have abundant intraparticle pores and are prone to particle breakage. This often leads to poor engineering properties, which poses a challenge to coastal infrastructure construction. A study using bio-cementation to improve the engineering properties of calcareous sand is presented in this paper. The macro- and microscopic properties of bio-cemented calcareous sand were characterized by drained triaxial tests and scanning electron microscopy observations. Experimental results show that the precipitated calcium carbonate can effectively fill the intra- and interparticle pores and bond adjacent particles, thus enhancing the shear strength of calcareous sand. The special structures (e.g. abundant intraparticle pores and rough surface) and mineral components (i.e. calcium carbonate) of calcareous sand are beneficial for improving bacterial retention in soil, which leads to a relatively uniform and dense calcium carbonate distribution on the sand particle surface, exhibiting a layer-by-layer growth pattern. This growth pattern and the abundant interparticle pores would result in less effective calcium carbonate. The strength enhancement of bio-cemented calcareous sand is significantly lower than that of bio-cemented silica sand at the same calcium carbonate content, which may be caused by the differences in the following: (a) soil skeleton strength; (b) the amount of effective calcium carbonate; and (c) interparticle pore-filling of calcium carbonate.

钙质砂具有丰富的颗粒内孔隙，并且易于破碎。这通常导致不良的工程性能，这对沿海基础设施建设构成了挑战。本文提出了一种利用生物胶结来改善钙质砂的工程性能的研究。通过排水三轴试验和扫描电子显微镜观察表征了生物胶结钙质砂的宏观和微观特性。实验结果表明，析出的碳酸钙可以有效地填充颗粒内和颗粒间的孔隙并结合相邻的颗粒，从而增强了钙质砂的剪切强度。特殊结构（例如大量的颗粒内孔隙和粗糙的表面）和矿物成分（即 钙质砂质的碳酸钙）有利于改善细菌在土壤中的滞留性，从而导致砂粒表面碳酸钙分布相对均匀且致密，表现出逐层生长的模式。这种生长方式和丰富的颗粒间孔将导致碳酸钙的有效性降低。在相同的碳酸钙含量下，生物水泥钙质砂的强度增强明显低于生物水泥硅砂的强度增强，这可能是由于以下方面的差异造成的：（a）土壤骨架强度；（b）有效碳酸钙的量；（c）碳酸钙的颗粒间孔填充。呈现出逐层增长的模式。这种生长方式和丰富的颗粒间孔将导致碳酸钙的有效性降低。在相同的碳酸钙含量下，生物水泥钙质砂的强度增强明显低于生物水泥硅砂的强度增强，这可能是由于以下方面的差异造成的：（a）土壤骨架强度；（b）有效碳酸钙的量；（c）碳酸钙的颗粒间孔填充。呈现出逐层增长的模式。这种生长方式和丰富的颗粒间孔将导致碳酸钙的有效性降低。在相同的碳酸钙含量下，生物水泥钙质砂的强度增强明显低于生物水泥硅砂的强度增强，这可能是由于以下方面的差异造成的：（a）土壤骨架强度；（b）有效碳酸钙的量；（c）碳酸钙的颗粒间孔填充。（b）有效碳酸钙的量；（c）碳酸钙的颗粒间孔填充。（b）有效碳酸钙的量；（c）碳酸钙的颗粒间孔填充。