海水海砂再生混凝土的基本力学性能

利用海水、原状海砂及再生粗骨料，制备了设计预期强度为C20~C50的海水海砂再生混凝土。通过240个标准立方体(150 mm×150 mm×150 mm)和96个棱柱体(150 mm×150 mm×300 mm)试件，完成了工作性能、立方体抗压强度、轴心抗压强度、劈裂抗拉强度以及弹性模量试验，研究了海水海砂再生混凝土的基本力学性能；最后基于试验数据，得到了海水海砂再生混凝土立方体抗压强度与轴心抗压强度关系公式以及弹性模量与轴心抗压强度关系公式。结果表明:海水海砂再生混凝土工作性能良好，C40和C50强度等级的坍落度比一般再生混凝土分别提高5%和33%；立方体抗压强度、轴心抗压强度和劈裂抗拉强度随着龄期变长而增加，且长期强度趋于稳定；与普通混凝土相比，海水海砂再生混凝土7 d立方体抗压强度提高13%~52%，28 d抗压强度降低约5%，90 d抗压强度降低约15%，180 d抗压强度降低18%~29%；海水海砂再生混凝土28 d弹性模量比普通混凝土略有降低，降低幅度在14%以内；再生粗骨料对混凝土力学性能、工作性能的影响大于海水海砂。

Basic Mechanical Properties of Seawater Sea-sand Recycled Concrete

The seawater sea-sand recycled concrete with the anticipated design strength of C20-C50 was prepared using the seawater, sea-sand and recycled coarse aggregate. Based on 240 standard cubes (150 mm×150 mm×150 mm) and 96 prism specimens (150 mm×150 mm×300 mm), the workability, cube compressive strength, axial compressive strength, splitting tensile strength and elastic modulus were tested to investigate the basic mechanical properties of seawater sea-sand recycled concrete. Finally, based on the test data, the relationships between the cube compressive strength and axial compressive strength, the elastic modulus and axial compressive strength of seawater sea-sand recycled concrete were obtained. The results show that the workability of seawater sea-and recycled concrete is well enough, and the slump of C40 and C50 seawater sea-sand recycled concrete increases by 5%, 33% than recycled concrete respectively. The cube compressive strength, axial compressive strength and splitting tensile strength increase with age, and the long-term strength tends to be stable. Compared with the ordinary concrete, the 7 d cube compressive strength of seawater sea-sand recycled concrete increases by 13%-52%, while the 28 d strength reduces about 5%, the 90 d strength reduces about 15%, and the 180 d strength reduces by 18%-29%. The 28 d elastic modulus of seawater sea-sand recycled concrete is slightly lower than that of ordinary concrete, and the decrease is within 14%. The effects of recycled coarse aggregate on the mechanical properties and workability of concrete are greater than those of seawater and sea-sand.