有早期受荷经历的钢纤维混凝土强度试验研究

通过对钢纤维混凝土在未达到设计强度前曾受过荷载非破坏性试验的试件进行后期强度试验,研究了这种早期受荷经历对钢纤维混凝土抗折强度、劈裂抗拉强度和轴心抗压强度的影响,进行了改变早期加荷时间、早期荷载水平和钢纤维掺量等因素的比较,并与普通混凝土做对比。试验结果表明,早期受荷使钢纤维混凝土的后期强度降低,这种不利影响比对普通混凝土的影响小,但在低含纤率时要给予足够重视;在工程中如需要在较早时期作用较大荷载时,增加钢纤维掺量是减小其后期抗折和抗拉强度降低幅度的一项有效措施,并做了相关的机理分析。

EXPERIMENTAL STUDY ON STRENGTHS OF STEEL FIBER REINFORCED CONCRETE WITH EARLY-AGE LOADING HISTORY

An experimental research project was carried out to determine the modulus of rupture,splitting tensile and compressive strengths of steel fiber reinforced concrete(SFRC) ever loaded at early ages.The specimens were first subjected to a load nondestructively at early ages and their strengths were then tested at age of 28 days.The effects of the age and the stress level of the early loading,as well as the contents of steel fibers,were investigated.The test results were then compared with those for plain concrete specimens.It shows that the early-age loading decreases the 28-day strengths of SFRC and this unfavorable effect is smaller than that for plain concrete because of steel fibers.With the increase of the contents of steel fibers,the 28-day strengths of SFRC influenced by early-age loading can be significantly improved,especially for the modulus of rupture and the splitting tensile strength.This is a useful measure in engineering practice to avoid severe weakening of concrete when it has to be heavily loaded at very early ages.