Some useful tips to enhance the longevity of concrete piles
If concrete is mixed perfectly and compacted to a solid impervious, the longevity of all the construction materials is significantly increased in a non aggressive atmosphere.
The strength of concrete is influenced by sulphate and sulfuric acid that takes place normally in soils, erosive chemicals existent in industrial waste in fill materials and organic acids and carbon dioxide existent in ground water.
A solid, properly compacted concrete can efficiently safeguard the concrete piles, pile cap and ground beams against the attack by sulphates. The low penetrability of dense concrete resists or significantly controls the ingress of the sulphates into the pore spaces of the concrete.
That's why high strength precast concrete piles are mostly recommended for application. Although these are not acceptable for all the site conditions and bored cast in situ / driven cast in situ piles, so, at the time of application, these should be designed perfectly to attain necessary degree of impenetrability and defiance to aggressive action.
Both high alumina cement and super sulphated cement are not suitable for piling work. As an alternative, reliance is provided on the resistance of solid impervious concrete that is formed with a low water cement ratio. Coating of tar or bitumen on the surface, metal sheeting or glass fibre wrapping filled with bitumen may be chosen.
A layer of heavy gauge polythene sheeting provided on a sand carpet or on blinding concrete is arranged to safeguard pile caps and ground beams on the underside. The vertical sides are safeguarded once the formwork is eliminated with the use of hot bitumen spray coats, bituminous paint, trowelled on mastic asphalt or adhesive plastic sheeting.
Preventative measures against the aggressive action caused by sea water on concrete should only be taken into consideration with regard to precast concrete piles. Cast in situ concrete is utilized only as a centering to steel tubes or cylindrical precast concrete shell pills. The precast concrete piles for marine condition, a minimum ordinary portland cement content of 360 kg/m3 and a maximum water cement ratio of 0.45 by weight should be chosen.