高强流态膨胀混凝土力学性能和膨胀行为

研究了高流态膨胀混凝土的强度性能、膨胀性能以及强度与膨胀的协调发展性能,考察了流态条件下中强和高强混凝土中膨胀剂的作用效应及细掺料对其的影响。研究表明高强流态膨胀混凝土的膨胀行为有其特殊性：在不加磨细矿渣(blast furnace slag,BFS)时,水养1d出现自收缩,整个硬化过程膨胀受到抑制,原因在于高强流态膨胀混凝土较高的强度,特别是较高的早期强度限制了膨胀的发挥,在混凝土内部存在“自约束效应”。掺加BFS后,未发现自收缩现象,限制膨胀率大于对应的未掺BFS时的限制膨胀率。BFS的加入使高强膨胀混凝土早期强度降低,膨胀效应得以较充分发挥。对比中低强膨胀混凝土分析认为：过高的强度(特别是早期强度)会抑制混凝土膨胀的发挥,而较低的强度(特别是早期强度)则会导致更多的膨胀变为无效膨胀。强度与膨胀协调发展这一膨胀混凝土的基本规律对于高强流态膨胀混凝土仍然适用且更为重要。

INVESTIGATION ON MECHANICAL PROPERTY AND EXPANSION BEHAVIOR OF HIGH STRENGTH SUPERPLASTICIZED EXPANSIVE CONCRETE

s: The characteristics of strength, expansion as well as coordination between strength and expansion of a superplasticized middle-strength and high-strength concrete were investigated. The effects of expansive admixture and fine possolanic powder(such as fly ash, blast furnace slag, etc.) in the concrete were also researched. The results show that the expansion of superplasticized high-strength expansive concrete has its characteristics: autogenous shrinkage occurs in 1 d standard curing, and expansion is compressed in whole hardening process. The reason is high strength especially high early strength in the concrete confines expansion effect, and there is "self-restricted effect" in it. When blast furnace slag(BFS) is added in, autogenous shrinkage of superplasticized high-strength expansive concrete in 1 d standard curing is disappeared, restricted expansion ratio of it increases than that without BFS. Use of BFS makes early strength of the concrete decreases, so expansion effect is bring into play. Too much high strength (especially high early strength) can confine expansion, but low strength(especially low early strength) can make expansion to be no effect. Coordination development between strength and expansion , the basic principle of expansive concrete, is not only suitable for superplasticized high-strength expansive concrete, but also more important.