废弃混凝土代替天然石灰石煅烧水泥熟料实验

从4个不同地点取得4个以破碎石灰石为粗集料的废弃混凝土样品,破碎、分离,获得以石灰石为主的颗粒,取代天然石灰石作为钙质原料煅烧出4个波特兰水泥熟料样品,并与重庆拉法基水泥厂生产的熟料和市售水泥样品进行对比.研究结果表明:废弃混凝土熟料的4种主要矿物的XRD特征峰明显;游离CaO低于1%;可以用其制备出52.5级硅酸盐水泥.

Using waste concrete as a replacement for natural limestone to produce cement clinker

Four samples of waste concrete with crushed limestone as coarse aggregate were collected from four different demolition sites.Each sample was crushed into particles which were then screened by sieves to remove smaller particles of given size.The residue was retained for use.Most of the residue was the crushed limestone;it was used to replace natural limestone as the calcareous raw material to produce cement clinker.These four clinker samples were compared with the similar Chongqing Lafarge cement clinker and some selected Portland cements on the market.The comparison results of XRD indicated that the XRD characteristic apex of the four principal compounds in the usual cement clinkers,C3S,C2S,C3A and C4AF,are strong enough in the clinkers produced by the waste concretes.All the free CaO content in the clinkers produced by the waste concretes was less than 1%,meeting the requirement of a given Chinese standard.It can be used to prepare Portland cements with strength grade of 52.5.The experimental results offer theoretical and technological guidance for efficiently reusing waste concretes.