超高强混凝土补偿收缩措施的研究

Study of Shrinkage-Compensating of Ultra High-strength Concrete

针对超高强混凝土水胶比小、自收缩大等特点,研究了不同膨胀源膨胀剂和多孔掺合料对超高强混凝土工作性能、力学性能和自收缩性能的影响。结果表明,膨胀源为Mg O的BTMG膨胀剂水化较慢,反应耗水少,晶体膨胀能大,掺BTMG超高强混凝土早期(3d)膨胀效果不明显,后期具有持续膨胀效果。预吸水的稻壳灰(RHA)和沸石粉(NZ)均能在养护后期释放水分,缓解混凝土内部湿度的降低,一定程度上弥补了混凝土自收缩,但RHA活性较NZ高,孔结构更为丰富,配制的超高强混凝土工作性能和强度损失小;BTMG与RHA复合后使用可将二者优势互补,提高混凝土体积稳定性和后期强度。

As with low water-binder ratio and high autogenous shrinkage of ultra-high strength concrete（UHSC）, influence of expansive agent with different expansion sources and porous mineral admixture on workability, mechanical properties and autogenous shrinkage of UHSC were studied. Results showed that the hydration rate of expansive agent with expansion sources of Mg O was slower and hydration process needed littler water than other expansive agents, which resulted in BTMG had little effect on shrinkage-compensation of UHSC at early age, and much useful effect at later age. Inside water of pre-wet rice husk ash（RHA） and natural zeolite（NZ） would be released along with curing age, which improved volume stability of UHSC because the inside humidity of UHSC increased. The pozzolanic activity of RHA was higher and pore structures diversed more than NZ, making UHSC with better workability and compressive strength. Under the compound use of BTMG and RHA, UHSC got high volume stability and compressive strength with stack effect.