可自修复的高延性混凝土(ECC)在机场道面的适用性分析

Feasibility study of engineered cementitious composites(ECC)with self-healing capacity for airfield pavement

在飞机荷载与环境荷载长期共同作用下,机场道面易出现裂缝、接缝和竖向位移类病害,使运营阶段维修成本高。提出将具有自修复功能的高延性水泥基材料(ECC)用于机场道面,以控制裂缝发展、实现无缝连接;并利用ECC因二次反应而使微裂缝愈合的特性,减少路面维护工作,延长使用寿命。通过试验手段研究了ECC材料应用于机场道面的力学行为、自修复行为和早期开裂潜能。试验结果表明:机场道面用ECC材料在拉伸荷载作用下,其拉伸应变可达3.67%(约为普遍混凝土的400倍);在弯曲荷载作用下,其竖向弯曲变形可达6.33 mm;抗压强度与弯曲强度分别为43.9 MPa和12.68 MPa,可满足机场道面的使用要求。在受约束条件下,ECC表现出较低的早期开裂潜能。由于自修复能力,裂损ECC的拉伸刚度、拉伸应变与拉伸强度几乎可恢复至未裂时的程度;其水渗透系数随自修复进程逐渐降低,最终达到未裂时的渗透水平。研究结果表明ECC材料用于无缝机场道面具有较高适用性。

Under the effects of mechanical and environmental loading,airfield pavement is prone to distresses of cracking,joints damage and vertical displacement of panels,which results in frequent maintenance.In order to control propagation of cracks and achieve jointless function,this study attempts to use engineered cementitious composites(ECC)as an airfield pavement material for its high ductility and intrinsic self-healing capacity.Damage in ECC can be healed by secondary hydration,thus reducing the maintenance cost and prolonging service life.In this paper,the mechanical properties of ECC and its self-healing behavior as well as the cracking potential at early age of ECC were investigated.The result shows that the tensile strain of ECC can reach 3.67%under the action of tensile load,(about 400 times higher than that of ordinary concrete)and the vertical deflection can reach 6.33 mm under flexural load.The flexural and compressive strength is 12.68 MPa and 43.9 MPa,respectively,which meets requirements of airfield pavement.Under restrained shrinkage,ECC is expected to have a low tendency towards fracture failure.With self-healing,the tensile stiffness,tensile strain and tensile strength of damaged ECC can almost be restored to the extent that it was not cracked.The water permeability coefficient of pre-damaged ECC decreases gradually to that of a virgin one.It can be concluded that ECC material has strong feasibility for jointless airfield pavement.