concrete Gas diffusion Water vapour diffusion Water vapour diffusion Ionic diffusion Water absorption Ionic diffusion Ionic diffusion Water permeability Flow constants · Permeability- a rate of flow of fluid into a porous solid of concrete. · Diffusivity- situation where gas or liquid will be transmitted through the substance. · Sorptivity- a process where liquid is absorbed by capillarity Curing Degradation of concrete · Chemical affects- reactions with sulfates, sea water, acids and alkalis · Physical affects- frost, fire, wind and water erosion Degratation of concrete Frost damage Sea water attack Durability of steel in concrete · Shear strenght Corrosion · Compensate tendons, stressed areas
pores and capillaries which fulfill with water. In laboratories several test have been worked out to measure the permeability but in real life we have a similar situations in marine areas. Next, there are three major types of flow constants for concrete. (slide) Firstly there is permeability which is a rate of flow of fluid into a porous solid of concrete. Then comes diffusivity- a situation where gas or liquid will be transmitted through the substance. And finally there is sorptivity which is a process where liquid is absorbed by capillarity. When the concrete is drying, it is very important to cure it well. (slide) It means watering the concrete to keep all the previous factors as low as possible. (slide) Degradation of concrete is mainly caused by chemical affects such as reactions with sulfates, sea water, acids and alkalis and physical affects including frost, fire, wind and water erosion. The chemical processes are complicated and need special circumstances to react
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