MOISTURE FLOW INTO CONCRETE EXPOSED TO FROST AND ICE

Exposure of concrete to freeze/thaw, ice and moisture causes transport in the material and the mechanisms responsible are reviewed. Hydraulic pressure may cause transport during both freezing and thawing whereas suction under the curved meniscus between ice and water in the pores is increasingly active as freezing progresses from surface inwards. Diffusion towards cold side requires a “trapping”, here suggested in the air voids. Internal frost damage with cracking causes increased concrete volume and suction of water from the surface. Ice pressure towards a rough concrete surface can cause very high local Hertzian indentation contact pressure for a wide range of concrete surface roughness. Even though plasticity of ice can reduce the contact pressure it can be high enough during short time to cause melted water and water from the liquid like layer on ice to be pressed into the concrete. Damage by abrasion of moving ice sheets on concrete structures is likely caused by this indenting pressure of concrete in ice.