Properly mixed concrete for a dense impermeable mass is the most durable of all building materials and there is no cause for concern about its long-term durability in a non-aggressive environment. However, concrete can be attacked by sulfate and sulfuric acid By naturally occurring, corrosive chemicals in the soil that may be present in industrial waste in the fill material and by organic acids and carbon dioxide present in groundwater as a result of rotting vegetables. Attack by sulfates is a decomposition process whereas the action of organic acids or dissolved carbon dioxide is one of leaching. The attack by sulfuric acid combines the characteristics of both processes. The severity of attack by soluble sulfates should be assessed by determining the soluble sulfate content and the ratio of the various Cat ions present in the soil aqueous extract. These determinations should be made in all cases where the sulphate concentration in the soil sample is high 0.5%,

A compact, well compacted concrete provides the best protection against the attack of sulfates on concrete piles, pile caps and ground beams. The low permeability of dense concrete prevents or greatly limits the penetration of sulfates into the pore spaces of the concrete. For this reason high strength precast concrete piles are the most favorable type to use. However they are not suitable for all site conditions and bore cast in situ / driven cast in situ piles if adopted should be designed to achieve the required degree of impermeability and resistance to aggressive action. Neither high alumina cement nor super sulphate cement is used for piling work. Instead, a . The resistance of dense impermeable concrete made from is kept dependent on low water cement ratio, Surface tar or bitumen coating, metal sheet or bitumen impregnated glass fiber wrapping can be adopted.

Pile cap and ground beam may be protected at the bottom by a layer of heavy gauge polythene sheet laid over sand carpet or blinding concrete. Vertical sides can be preserved after deleting the form work Hot Bitumen Spray Coat Applying Bituminous Paint, mastic sculpted on asphalt or adhesive plastic wrap.

Precautions against aggressive action by sea water on concrete should only be considered with respect to precast concrete piles. Cast in situ concrete is used only as a heart for steel tube or cylindrical precast concrete shell tablets. For Precast Concrete Pile for Marine Condition, Minimum Common Portland Cement Content 360 kg/m3 and a maximum 0.45. water cement ratio of Should be adopted by weight.

Er. Mukesh Kumar

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Er. Mukesh Kumar is Editor in Chief and Co-Funder at Civil Engineering Website. Mukesh Kumar is a Bachelor in Civil Engineering From MIT. He has work experience in Highway Construction, Bridge Construction, Railway Steel Girder work, Under box culvert construction, Retaining wall construction. He was a lecturer in a Engineering college for more than 6 years.