基于河套灌区盐碱环境及凌汛期含冰水冻结作用下对改性废旧轮胎胶粉自保温混凝土在水工建筑物的适应性研究

The researches are focused on discussing the unconventional frozen condition of hydraulic structures in the saline environment of Hetao Irrigation and found A special modified concrete, adding waste tire rubber powder and natural pumice, could reduce thermal conductivity and improve hydraulic concrete capabilities to resist unconventional freeze damage in this paper. Based on the preliminary research projects, we proposed a plan to build dam and lining segment in typical branch of Yongji canal. Using embedded temperature conduction and displacement sensing device, with reverse deduction method to study mechanical properties and pore state of insulation concrete, which were modified with adding waste tire rubber powder, under salinity environment of Hetao Irrigation and freeze damage during Yellow river ice flood season. We intend to systematically analyze the mechanical properties distribution in the transition zone around the coarse aggregate during freeze damage. United CT image reconstruction with technology of NMR (nuclear magnetic resonance), it researched on the microscopic mechanism and the mix proportion parameters which were impacted by mechanical properties of different of powder size and modified program at interfacial region. We can acquire important ideas from the result of micromechanical analysis under salinity environment and freeze damage. It could be used to design optimization of dam concrete mix proportion and improving the durability of dam concrete. This projects, research on extending irrigation service life of hydraulic structures, expanding utilization of waste tire and increasing employment rate. It will have important scientific and engineering applications.

本文针对河套灌区特殊盐碱环境和黄河分凌分汛过程中水工建筑物非常规的冻结状态，利用特殊改性橡胶天然浮石降低混凝土导热系数和改性胶粉温变弹性性能改善水工混凝土抵抗非常规冻结破坏能力。在前期研究基础上，拟在灌区永济渠典型支段建制坝体段和衬砌段，利用预埋温度传导及位移传感装置，采用“逆向推演法”研究盐碱环境及凌汛期含冰水冻结作用下混凝土中改性胶粉颗粒与浆体界面区的力学特性、孔隙状态；拟系统研究在冻结过程中粗骨料周围过渡区力学性能的分布规律，结合界面区CT 图像重建和核磁共振检测技术，研究胶粉不同粒径、不同改性方案下配合比参数对界面区力学特性的影响规律并揭示其微观机理。研究成果为优化本地区水工混凝土配合比设计，改善混凝土材料的耐久性能，并为盐碱环境及凌汛期含冰水冻结作用下水工混凝土细观力学分析提供重要思路，提高灌区水工建筑物使用寿命，增加地区废旧轮胎利用率，提高就业，具有重要的意义。

本项目针对河套灌区特殊盐碱环境和黄河分凌分汛期为研究背景，以内蒙古地区天然浮石作为粗骨料，通过对废旧橡胶颗粒进行改性，研究改性橡胶对天然浮石混凝土力学特征的影响。应用核磁共振检测技术，从研究改性橡胶影响天然浮石混凝土宏观性能的本质出发，以改性橡胶天然浮石混凝土孔隙度、横向弛豫时间T2谱等参数为依据，同时结合力学性能测试、BT-1800动态图像颗粒试验、亲水性试验和环境扫描电镜试验等技术手段对核磁共振结果进行对比和论证。研究盐碱环境及凌汛期含冰水冻结作用下天然浮石混凝土中改性胶粉颗粒与浆体界面区的力学特性、孔隙状态。研究在冻结过程中粗骨料周围过渡区力学性能的分布规律，结合界面区CT图像重建和核磁共振检测技术，研究胶粉不同粒径、不同改性方案下配合比参数对界面区力学特性的影响规律并揭示其微观机理。结果表明，表面改性剂对胶粉表面产生的侵蚀作用和极性化学官能团的引入是改性成功的关键，利用司班40、十二烷基苯磺酸钠、二氯异氰尿酸钠改性剂可以提高橡胶颗粒球状度、圆形度，减少了橡胶粉表面不规则形状的纤维。改性橡胶可以提高橡胶颗粒与水泥混凝土的相容性和适宜性，使得橡胶天然浮石混凝土T2谱分布峰值减小并全部向小孔隙方向偏移，减小了孔隙率和孔径分布，从而改善了橡胶天然浮石混凝土的力学性能和抗冻耐久性。其原因归结于，改性橡胶天然浮石混凝土的多孔特征，橡胶粉弹性体特征均对冻胀裂缝的发展起到阻碍作用。研究成果为优化本地区水工混凝土配合比设计，改善混凝土材料的耐久性能，并为盐碱环境及凌汛期含冰水冻结作用下水工混凝土细观力学分析提供必要的研究背景和理论基础。