Properties of mortars made by uncalcined FGD gypsum-fly ash-ground granulated blast furnace slag composite binder

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• 作者：Shiyun Zhong ; ^{tjzhongshiyun@163.com} ; Kun Ni ; Jinmei Li
• 关键词：Uncalcined flue gas desulphurization gypsum ; Fly ash ; Ground granulated blast furnace slag ; Release of
• 刊名：Waste Management
• 出版年：2012
• 期刊代码：70_0956053x
• 类别：env
• 出版时间：July, 2012
• 卷：32
• 期：7
• 页码：1468-1472
• 文件大小：721 K

摘要

A series of novel mortars were developed from composite binder of uncalcined FGD gypsum, fly ash (FA) and ground granulated blast furnace slag (GGBFS) for the good utilization of flue gas desulphurization (FGD) gypsum. At a fixed ratio (20%) of GGBFS to the composite binder, keeping consistency of the mortar between 9.5 and 10.0 cm, the properties of the composite mortar were studied. The results show that higher water/binder (W/B) is required to keep the consistency when increasing the percentage of FGD gypsum. No obvious influences of the W/B and content of FGD gypsum on the bleeding of paste were observed which keeps lower than 2%under all experimental conditions tried. The highest compressive and flexural strengths (ratio is 20%FGD gypsum, 20%GGBFS and 60%FA) are 22.6 and 4.3 MPa at 28 days, respectively. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) results indicate that massive ettringite crystals and C-S-H gels exist in the hydration products. At 90 days the mortars with FGD gypsum is dramatically smaller drying shrinkage (563-938 micro strain) than that without FGD gypsum (about 2250 micro strain). The release of the from the mortar was analyzed, indicating that the dissolution of sulfate increases with FGD gypsum. The concentration of releasing from the mortar with 10%FGD gypsum is almost equal to that obtained from the mortar without FGD gypsum. The release of from the mortar with 20%FGD gypsum is 9200 mg路m^鈭?, which is lower than that from the mortar with 95%cement clinker and 5%FGD gypsum.