轻质超高性能混凝土的制备及性能形成机理

以预湿轻集料、硅酸盐水泥、硅灰、粉煤灰微珠、钢纤维、膨胀剂等为原材料,采用轻质、超高强度与低收缩协同设计方法制备了一种轻质超高性能混凝土材料,并研究其性能的主要影响因素和形成机理。结果表明:制备的轻质超高性能混凝土可实现自流平、干表观密度低至2040 kg/m3、28 d抗压/抗折强度可达120/18 MPa、弯曲韧性指数I₂₀可至21.8、56 d收缩率低至2.62×10^–4;其性能的形成主要源于粉煤灰微珠的滚珠效应、轻集料的轻质多孔效应、预湿轻集料的内养护与拱壳效应,以及预湿轻集料内养护与膨胀剂的叠加效应。

Preparation and Formation Mechanism of Lightweight Ultra-high Performance Concrete

Lightweight ultra-high performance concrete(LUHPC)was prepared with pre-wetting lightweight aggregate,Portland cement,silica fume,fly ash microsphere,steel fiber and expansion agent as raw materials.The influencing factors on the performance of LUHPC and the developing mechanism were investigated.The results show that the as-prepared LUHPC has a superior performance.The LUHPC can be self-compacting and has a low dry apparent density of 2040 kg/m3.The 28-d compressive strength and flexural strength are 120 MPa and 18 MPa,respectively.The bending toughness index is 21.8,and the 56-d shrinkage rate is 2.62×10^–4.The superior performance of the LUHPC is mainly due to the ball effect of fly ash microsphere,the lightening,internal curing,"arch-shell"structure effects of pre-wetting lightweight aggregate and the shrinkage-compensating effect of expansion agent.