桥梁清水混凝土设计方法与匀质性控制

根据桥梁工程结构特点，提出了桥梁清水混凝土的配合比优化设计方法，制备出粘聚性与包裹性好、流动度佳，且具有优良力学性能的C30~C50高性能清水混凝土。通过对混凝土拌合物含气量、硬化试件不同部位显微硬度与微观结构的测试，分析了增粘剂对其匀质性的影响规律。试验表明：对于C30桥梁清水混凝土，掺5×10 -5的纤维素醚或掺6%的硅灰时，混凝土的含气量不超过2%，浆体旋转粘度值在1 900~2 000 MPa·s之间，试件不同部位显微硬度值接近，匀质性好，结构密实。

Design method and homogeneity control of bridge fair-faced concrete

According to the structural characteristics of bridge engineering, the mix optimization design method of bridge fair-faced concrete was presented, and C30~C50 concrete with high cohesion and package, outstanding fluidity and excellent mechanical properties were prepared. Through the test of air content of fresh concrete, micro hardness and micro structure in different parts of hardened concrete specimens, effects of viscosity-modifying admixtures on homogeneity of concrete were discussed. The results showed that the composition of bridge fair-faced concrete were relatively homogeneous, and the microstructure were relatively dense. When C30 concrete mixed with 5 × 10 -5 cellulose ether or 6% silica fume (mass fraction of cementitious material), air content of fresh concrete were less than 2%, and slurry viscosity values were between 1 900 and 2 000 MPa·s. Also, the micro hardness values in different parts of hardened concrete specimens were closed. The results were applied in practical bridge engineering, which generally meets the apparent quality requirements of bridge fair faced concrete.