氢氧化铝/有机改性蒙脱土复合改性沥青性能研究

采用氢氧化铝(ATH)和两种有机改性蒙脱土(OMMT-C、OMMT-F)对沥青进行阻燃抑烟改性,旨在提高隧道沥青路面的阻燃抑烟性能。通过测试三大指标来评价ATH/OMMT复合改性沥青的常规性能,测试极限氧指数(LOI)与烟密度(SDR)来评价其阻燃抑烟性能,利用动态剪切流变(DSR)试验研究其流变性能。基于综合指数法优选出ATH/OMMT复合改性沥青的最佳复掺配比,通过热重(TG)试验分析了ATH/OMMT复合改性沥青的热解燃烧特性并建立了阻燃性能预测模型。研究结果表明,ATH/OMMT复合阻燃剂提高了沥青的稠度与软化点,降低了沥青的低温性能。当ATH掺量为10%(质量分数),OMMT-C掺量为3%(质量分数)时,复合改性沥青的综合性能最优,其极限氧指数大于23%,符合路用阻燃沥青的标准,同时烟密度相对基质沥青降低了33.9%,初始分解温度较基质沥青提高了3~6 ℃,分解残余量提高率最高可达61.3%。ATH/OMMT-C复合阻燃剂通过阻隔热交换通道提高了沥青的阻燃抑烟性能,通过增加沥青的弹性成分提高了沥青的复数模量与车辙因子,以及高温抗变形能力。

Properties of Asphalt Modified by Aluminum Trihydrate/Organic Montmorillonite Composite

The objective of this research is to develop a flame retardant asphalt modified by aluminum trihydrate (ATH) and two kinds of organic montmorillonites (OMMT-C, OMMT-F) and investigate the effect of ATH/OMMT composite flame retardant on properties of styrene-butadiene-styrene (SBS) modified asphalt. The conventional performance of ATH/OMMT modified asphalt was evaluated by testing penetration, softening point and ductility. The limit oxygen index (LOI) and smoke density (SDR) were obtained to investigate the flame retardant and smoke suppression performance of ATH/OMMT modified asphalt. The optimum content of ATH/OMMT composite flame retardant was determined based on the comprehensive index method. The rheological properties of ATH/OMMT modified asphalt were investigated by dynamic shear rheological (DSR) test. The pyrolysis and combustion characteristics of ATH/OMMT modified asphalt were analyzed by thermogravimetric (TG) test. The results reveal that ATH/OMMT composite flame retardant increases the softening point and reduces the low temperature performance of SBS modified asphalt. However, the flame retardant and smoke suppression performance are greatly enhanced by the additive of ATH/OMMT composite flame retardant. The initial decomposition temperature of the composite modified asphalt is 3 ℃ to 6 ℃ higher than that of SBS modified asphalt. When the ATH content is 10% (mass fraction) and the OMMT-C content is 3% (mass fraction), LOI value of asphalt is more than 23%. At the same time, the smoke density of asphalt is reduced by 33.9%. Compared with SBS modified asphalt, the decomposition residual rate of composite modified asphalt increases up to 61.3%. ATH/OMMT-C composite flame retardant significantly increases the complex modulus and rutting factor, and improves the deformation resistance of asphalt at high temperature.