季冻影响下路用CFB灰混凝土孔隙特征及动态力学性能研究

Research on Pore Characteristics and Dynamic Mechanical Properties of Road CFB Ash Concrete under the Influence of Seasonal Freezing

通过室内冻融循环试验和SHPB动力学试验,探究冻融循环对CFB灰混凝土孔隙率的影响特征,分析高应变率作用下冻融循环次数和CFB灰掺量对混凝土动态力学性能的影响。根据公路建设季冻灾害与动载扰动的影响规律,分析CFB灰混凝土的路用可行性。研究表明:在冻融循环作用下,CFB灰混凝土的孔隙率与混凝土可承受的冻融循环次数呈对数关系,CFB灰掺量的增加使混凝土密实度提高,孔隙率减小;随着冻融循环次数的增加,混凝土的动态弹性模量、动态抗压强度呈对数减小,动态峰值应变呈对数增加,掺量为20%的CFB灰混凝土具有较强的动态抗压性能;在公路建设中,掺量不大于20%的CFB灰能有效降低混凝土孔隙率、提高动荷载承载力、改善混凝土的抗冻性。研究成果对于探究CFB灰混凝土力学性能、促进CFB灰混凝土在公路建设中的应用具有重要意义。

The influence of freeze-thaw cycle on the porosity of CFB ash concrete was studied by the laboratory freeze-thaw cycle test and SHPB dynamic test.The effects of freeze-thaw cycles and CFB ash content on dynamic mechanical properties of concrete under high strain rate are analyzed.The feasibility of CFB ash concrete is analyzed based on the influence of seasonal freezing disaster and dynamic load disturbance in highway construction.The results are as follows.Under the action of freeze-thaw circulation,the porosity of CFB ash concrete is logarithmic with the number of freeze-thaw cycles.With the increase of CFB ash content,the concrete density increases and the porosity decreases.The SHPB dynamic test was carried out on the freeze-thawed sample.With the increase of the number of test cycles,the dynamic elastic modulus and dynamic compressive strength of the sample decreased logarithmically.The dynamic peak strain increases logarithmically,and the 20%CFB ash concrete has strong dynamic compressive resistance.In highway construction,no more than 20%CFB ash can effectively reduce the porosity of concrete,increase the dynamic load bearing capacity,and improve the resistance to freezing damage of concrete.The research results are of great significance and reference value for exploring the mechanical properties of CFB ash concrete and promoting its application in highway construction.