化学激发对煤气化渣-水泥体系抗压强度影响机理研究

Influence Mechanism of Chemical Excitation on Compressive Strength of Slag Cement System in Coal Gasification

针对煤气化渣大量堆存造成的环境污染和固废资源浪费的问题,本工作采用化学激发方法来激发煤气化渣活性,探究不同激发剂对煤气化渣-水泥体系抗压强度的影响。试验选取硫酸盐类、碱类和聚合盐类激发剂,确定最优激发剂种类和掺量;通过扫描电镜(SEM)、X射线衍射(XRD)和热重分析(TG)等微观手段,研究不同激发剂对煤气化渣-水泥体系水化产物的影响。结果表明,硫酸盐类最优激发剂为硫酸钠,最佳掺量为2.5%,试样3 d、28 d抗压强度增长率分别达14.3%、3.4%;碱类最优激发剂为氢氧化钙,最佳掺量为0.5%,试样3 d、28 d抗压强度增长率分别达18.4%、1.8%;聚合铝最佳掺量为2.0%,试样3 d、28 d抗压强度增长率分别达24.0%、3.3%。加入激发剂后试样早期抗压强度均得到提高,微观特征表明试样水化程度加深,且有助于钙矾石和凝胶体等水化产物的生成,提高试样强度,为煤气化渣在水泥基材料中的应用提供了理论依据。

Aiming at the problems of environmental pollution and waste of solid resources caused by large amount of coal gasification slag,this paper uses chemical excitation method to stimulate the activity of coal gasification slag,and explores the influence of different activators on the compressive strength of coal gasification slag⁃cement system.Sulfate,alkali and polymeric salt activators were selected to determine the optimal type and dosage of activators.The effects of different activators on the hydration products of coal gasification slag⁃cement system were studied by means of scanning electron microscopy(SEM),X⁃ray diffraction(XRD)and TG.The results show that the optimal sulfate activator is sodium sulfate,and the optimal dosage is 2.5%.The compressive strength of the sample increases by 14.3%and 3.4%after 3 and 28 days,respectively.The optimal alkali activator was calcium hydroxide,and the optimal dosage was 0.5%.The compressive strength of the samples increased by 18.4%and 1.8%after 3 and 28 days,respectively.When the optimal content of polymeric aluminum is 2.0%,the compressive strength increases by 24.0%and 3.3%after 3 and 28 days,respectively.The early compressive strength of the samples was improved after the addition of the stimu⁃lating agent.The microscopic characteristics showed that the hydration degree of the samples was deepened,which was helpful to the formation of hydration products such as ettringite and gel,and improved the strength of the samples.This provided a theoretical basis for the application of coal gasification slag in cement⁃based materials.