Reinforced concrete in corrosive environment
Corrosion of reinforcing steel pose a significant threat for RC structures. corrosion will severely affect structures strength and reduce durability. deicing salt, sea water will cause reinforcing steel to corrode. special measures shall be taken for structures built in a corrosive environment such as coastal area and wastewater treatment plant. the influence of the environment shall be considered at the early stage of design. corrosion of steel can adversely affect reinforcing concrete. the following is the adverse effect of corrosion:
- rust will occupy a larger volume than the original volume of reinforcing steel. these will cause stress on concrete which can cause cracks and concrete spalling.
- rust will reduce the cross-sectional area of steel bars. this will reduce the tensile strength of steel.
- rust will impair the bond between concrete and reinforcing bars.
prevention of corrosion required special measures to be implemented during the design and construction stage. the following summarizes the measures can be taken to reduce the rust of reinforcing steel:
- concrete cover: sufficient cover shall be provided to minimize the effects of the aggressive chemical. also, it will delay the carbonation process effects on reinforcing steel.
- concrete mix and admixture: reducing of w/c will increase concrete impermeability. w/c can be reduced by using superplasticizers to enhance workability and reducing w/c at the same time. admixture such as silica fume and GGBS can contribute to increasing concrete impermeability. increasing impermeability will reduce significantly the ingress of aggressive chemical.
- coating of reinforcing steel: reinforcing steel can be coated to resist corrosion. epoxy coating can be used or dual coating of zinc alloy and epoxy coating.
- stainless steel reinforcing: using of stainless steel reinforcing will increase the durability of the concrete structure significantly.