植物纤维增强碱矿渣胶凝材料砌块砌体耐高温性能研究

Aiming at the traditional masonry structure with large energy consumption during production and insufficient ductility or other issues, the mechanical property tests, thermal performance tests and fine finite element analysis of the plant fiber reinforced alkali-activated slag cementitious material (AASCM) block masonry, have been chosen as breakthrough point to investigate the key parameters on the work and mechanical properties of block and slurry systematically, and then the mechanical behavior, optimized ratio, setting time and failure mechanism are revealed. Through the high-temperature mechanical property tests, the failure modes and damage mechanism of the plant fiber reinforced AASCM block, slurry and new masonry are revealed at high temperature and after high temperature. In addition, the high-temperature resistant safety design, damage assessment and repairing methods of new masonry will be put forward. Through the microscopic analysis after high temperature, the influence rules of microstructure change on these macroscopic mechanical properties of the block and slurry are shown. After completing the thermal performance tests of the AASCM block masonry and new masonry, their thermal parameters are determined. On the basis of experimental and analytical results, the section temperature field and finite element analyses are completed, and the finite element models of AASCM block masonry and new masonry are proposed. The advantages and disadvantages of their thermal performance are given intuitively, qualitatively and quantitatively. Finally, the effectiveness of the plant fiber reinforcing the thermal insulation properties of AASCM block is proved. The results from above research can provide the evidences and decision supports for the revise of relevant standards.

针对传统砌体结构生产能耗大和延性较差等问题，以植物纤维增强碱矿渣胶凝材料（AASCM）砌块砌体的力学性能试验、热工性能试验及精细化有限元分析为切入点，系统研究关键参数对砌块、砌筑浆体工作性能和力学性能的影响，揭示砌块、砌筑浆体的受力性能、优化配比、凝结时间和失效机理；通过高温力学性能试验，揭示高温下和高温后植物纤维增强AASCM砌块、砌筑浆体和新型砌体的破坏模式和损伤机理，提出新型砌体耐高温设计方法及高温损伤评估与修复方法；通过高温后微观分析，揭示砌块、砌筑浆体微观结构变化对其宏观力学性能的影响规律；完成AASCM砌块砌体和新型砌体的热工性能试验，确定其热工参数。在此基础上，完成截面温度场和变形有限元分析，建立AASCM砌块砌体和新型砌体的有限元模型，直观、定性和定量的给出其热工性能优劣，证明植物纤维对增强AASCM砌块保温隔热性能的有效性，为相关标准的进一步修订提供理论依据和决策支持。

植物纤维增强碱矿渣胶凝材料（AASCM）克服了AASCM抗拉强度低、延性和耗能能力差、收缩徐变大等缺点，兼有高比强度、高比刚度、优良的耐高温性能和节约资源、绿色环保的优点，是将工农业副产品资源化的有效途径之一，应用前景广阔。本项目进行了植物纤维增强AASCM力学性能和优化配比试验，获得了植物纤维增强AASCM砌块砌体的应力-应变关系曲线，揭示了其破坏模式，建立了植物纤维增强AASCM导热系数随温度变化的计算公式，揭示了纤维种类、纤维掺量、纤维处理方式和纤维弹性模量等对AASCM基体力学性能的影响规律，提出了植物纤维增强AASCM砌块砌体抗压强度随温度变化的计算公式。具体工作如下：.1.通过改变关键参数（碱激发剂种类、水玻璃模数、碱含量、水用量），考察关键参数对AASCM的力学性能（抗压强度、抗折强度）及工作性能（凝结时间、流动度）的影响。获得了以钾水玻璃模数为1.0、碱含量为14%，用水量为32%为砌块基体的优选配比，以钾水玻璃模数为1.0、碱含量为12%，用水量为35%为砌筑浆体的优选配比。考察植物纤维种类（麦秆、稻秆。玉米秆）和掺量对基体力学性能的影响；对比三种纤维处理方式（碱处理、酸处理、未处理），确定采用经碱处理的麦秆为所选植物纤维。获得了棱柱体应力-应变关系曲线、破坏形态及极限承载力。.2.得到麦秆增强AASCM单排孔砌块常温的抗压强度为10.75MPa，相当于标准混凝土砌块MU7.5，其高温抗压强度随温度升高而呈线性降低。600℃高温后，植物纤维对基体仍具有一定的拉结作用；而聚丙烯纤维在200～400℃高温后逐渐熔化，使基体呈突然性脆性破坏；200～400℃高温后，微细钢纤维改善了砌块受压破坏特征，呈明显塑性变形。通过回归分析，建立了植物纤维增强AASCM砌块抗压强度随温度变化的计算公式。完成了砌块热工性能试验，确定其导热系数、热扩散系数和比热容，证明植物纤维增强AASCM砌块属于保温材料，具有良好的保温隔热性能。分析不同纤维增强AASCM微观结构，揭示试件宏观力学性能急剧下降的主要原因。.3.获得不同纤维增强AASCM砌块砌体的常温和高温力学性能指标，揭示800℃高温后，植物纤维增强AASCM砌块砌体应力-应变关系曲线下降段呈明显塑性特征，表明植物纤维对AASCM基体塑性变形能力起到了改善作用。揭示不同纤维增强AASCM砌块砌体的高温破坏模式和损伤机理