钢渣激发剂对近海混凝土力学性能和耐久性的影响

Influence of Steel Slag Activator on Mechanical Property and Durability of Offshore Concrete

为提高近海混凝土的耐久性和钢渣粉在混凝土中的利用率,通过测试掺钢渣混凝土的流动度、凝结时间、力学性能、碳化深度和氯离子电通量,研究了硫酸钠、脱硫石膏、脱硫灰这3种激发剂以单掺或复掺方式对钢渣活性和混凝土抗氯离子能力和抗碳化性能的影响。结果表明:钢渣使水泥净浆的流动度下降,凝结时间延长,Na_(2)SO_(4)作激发剂可略微缩短凝结时间,矿粉和钢渣粉可一定程度减少混凝土坍落度的经时损失,但加入一定量的激发剂后会减弱这种效果;脱硫灰、Na_(2)SO_(4)、脱硫石膏这3种激发剂对混凝土的抗折强度有显著提升,特别是3%Na_(2)SO_(4)对抗折强度的贡献较大;Na_(2)SO_(4)与脱硫石膏复合激发剂对混凝土抗折强度的提升作用大于Na_(2)SO_(4)-脱硫灰复合激发剂和单掺激发剂;3种激发剂单掺对钢渣-矿粉混凝土7 d抗压强度略有改善效果,对后期抗压强度的改善效果不明显,但复合激发剂对混凝土抗压强度的提升较为显著,特别是3%Na_(2)SO_(4)和4%脱硫石膏复合激发剂对力学性能的提升效果较为显著;Na_(2)SO_(4)使混凝土的抗碳化性能和抗氯离子渗透性能分别提高了23.9%和43.7%,Na_(2)SO_(4)和脱硫石膏复合激发剂对耐久性的提升效果优于单一激发剂。脱硫灰、脱硫石膏、Na_(2)SO_(4)激发剂提高了钢渣的活性,进一步改善了混凝土的微结构,使得混凝土的力学性能和耐久性能提升。

To improve the offshore concrete durability and the steel slag powder utilization rate in concrete,the fluidity,setting time,mechanical properties,carbonation depth and chloride ion electric flux of steel slag concrete were tested.The influences of 3 kinds of activators(i.e.,sodium sulfate,desulfurization gypsum and desulfurization ash)on steel slag activity,chloride ion resistance and carbonation resistance of concrete were studied.The result indicates that the steel slag decreases the cement paste fluidity,and prolongs the setting time.As an activator,Na_(2)SO_(4) can slightly shorten the setting time.The mineral powder and steel slag powder can reduce the time loss to a certain extent caused by concrete slump;but a certain amount of activator will weaken this effect.The desulfurization ash,Na_(2)SO_(4) and desulfurization gypsum improve the flexural strength of concrete significantly,especially 3%Na_(2)SO_(4) contributes more to the flexural strength.The effect of Na_(2)SO_(4) and desulfurization gypsum composite activator on the flexural strength of concrete is greater than that of Na_(2)SO_(4) and desulfurization ash composite activator and single activator.When each of the 3 activators is mixed alone,the 7 d compressive strength of concrete with steel slag-slag powder is slightly improved,and the improvement effect on the later compressive strength is not obvious.However,the composite activator has the significant effect on the compressive strength of concrete,especially 3%Na_(2)SO_(4) and 4%desulfurization gypsum composite activator has the significant effect on mechanical properties.Na_(2)SO_(4) increases the carbonation resistance and chloride ion penetration resistance of concrete by 23.9%and 43.7%respectively.The effect of Na_(2)SO_(4) and desulfurization gypsum composite activator on durability is better than that of single activator.The desulfurization ash,desulfurization gypsum and Na_(2)SO_(4) increase the steel slag activity,further improving the microstructure of concrete,and improving the mechanical properties and durability of concrete.