新型碾压式导电混凝土功能材料力学性能试验与精细仿真分析

Mechanical experiments and precise simulation of a novel functional material:Electrically conductive roller-compacted concrete

碾压式导电混凝土(electrically conductive roller-compacted concrete,ERCC)是一种新型功能性材料,可通过自身电热性能解决高寒地区路面跑道人工除雪去冰效率低、大坝工程结构温控难等问题.本文开展了ERCC材料设计、物理试验与数值仿真分析研究.利用扫描电子显微镜(scanning electron microscope,SEM)测试分析了表面活性剂对ERCC浆体流动性、炭黑分散效果的改善机理;针对碾压成型的大型ERCC钻芯取样试件,开展了力学性能的宏观试验与X射线断层扫描(X-ray computed tomography,XCT)的细观试验;进而在材料试验的基础上,通过耦合连续介质、非连续介质计算方法进行ERCC精细化数值仿真分析,建立了基于真实骨料的ERCC细观模型,解决了传统混凝土细观模拟中XCT模型计算成本过高、非连续介质计算效率低、传统球体/多面体骨料模型的精细化程度差等问题.结果表明:ERCC表面活性剂可明显改善炭黑分散效果,采用碾压施工工艺成型质量较好,抗压强度为22.85 MPa,劈拉强度为1.72 MPa,弹性模量为23.7 GPa,孔隙体积比为1.05‰;在砂浆、界面强度一定时,增大骨料体积比,可不同程度提高ERCC的力学性能;精细化仿真计算结果与多个实际工程混凝土材料特性统计规律相吻合,相比传统混凝土细观模拟方法具有更好的适用性.

Electrically conductive roller-compacted concrete(ERCC)is a novel functional material,which can solve the problems of low efficiency of artificial snow removal and deicing on expressway and airport runway and the difficulty in temperature control of dam engineering structures.In this study,we designed ERCC and conducted an experimental study and numerical simulations on the designed ERCC.The improvement mechanism of surfactants on the fluidity of ERCC slurry and the effects of carbon-black dispersion were analyzed by scanning electron microscopy.Aiming at the large ERCC core-sampling specimen formed by rolling,macroscopic tests for mechanical properties and mesoscopic tests by X-ray computed tomography(XCT)were conducted.Based on the experiment,precise simulation of ERCC was performed by coupling the calculation methods of continuous and discontinuous mediums.We developed a mesoscopic model of ERCC based on real aggregate.The model overcomes the challenges of high cost of XCT models,low efficiency of discontinuous-medium calculation methods,and poor refinement of traditional sphere/polyhedral aggregate models in traditional continuous-medium calculation methods for concrete.The result shows that surfactants can significantly improve the effect of carbon-black dispersion on ERCC,and the forming quality of rolling construction technology is positive with compressive strength of 22.85 MPa,splitting strength of 1.72 MPa,elastic modulus of 23.7 GPa,and pore volume ratio of 1.05‰.The mortar and interface strengths of ERCC were constant,whereas with an increase in the volume ratio of aggregates,the mechanical properties of ERCC could be improved.The precise simulation results are consistent with the statistical laws of concrete material characteristics in many practical projects,and they have better applicability than traditional meso-simulations of concrete.