改性黄河砒砂岩复合材料试验研究

Study on Modified Feldspathic Stone Composite Materials

砒砂岩是黄河泥沙的主要来源之一,可通过碱激发的方法将其转变为建筑材料,实现其资源化。在矿粉掺量为20%、氢氧化钠为2%、密度为2.2 g/cm3及含水率为6%的条件下,研究了碱激发改性砒砂岩的软化系数随龄期的变化,并详细研究了氢氧化钠掺量、密度、矿粉掺量对碱激发改性砒砂岩抗压强度的影响。试验结果表明,碱激发改性砒砂岩软化系数随龄期的增长而提高,在矿粉掺量为20%、氢氧化钠为2%、密度为2.2 g/cm3、含水率为6%及龄期为28 d的条件下,改性砒砂岩的软化系数达到0.76(满足工程需求)。矿粉能够显著地提高改性砒砂岩的抗压强度,当矿粉含量为40%、密度为2.2 g/cm3和碱激发剂含量为2%时,改性砒砂岩7 d抗压强度能够达到32 MPa,相对于不加矿粉试样抗压强度提高627%。SEM和XRD分析结果表明,改性砒砂岩的水化产物为凝胶态的物质(C-S-H等),并且改性砒砂岩基体的微裂纹大量减少甚至消失。

Feldspathic stone is the main source of the Yellow River sediment. Feldspathic stone when combined with suitable alkali activators can be converted into geopolymer cement to realize the resources utilization of feldspathic stone. This paper studied the water resistance and the change of the water resistant coefficient with the age of Pisha Sandstone after the modified. And also studied the influence of the sodium hydroxide dosage,density of the modified feldspathic stone,slag powder dosage to the compressive strength of the modified feldspathic stone. With 20% slag,2% NaOH and 8% water,the water resistant coefficient of modified feldspathic stone reached 0. 76 at 28 days. With slag content was 40%（by weight）,the density of the modified feldspathic stone was 2. 2g/cm3 ,the alkali activator content was 2%,the 7 days compressive strength of the modified feldspathic stone can reach 32MPa. In comparison to samples which had no slag,the 7 days compressive strength increased by 602%. SEM and XRD were used to analysis microscopic morphology and reaction products of the modified feldspathic stone. It found a lot of the amorphous minerals which had gelling properties appeared,and the number of micro cracks in modified feldspathic stone were greatly reduced or even disappeared.