The foundation is the part of the structure that is in direct contact with the ground. Hence the foundation is attacked by soil, chemicals present in the water and mechanical abrasion and erosion.
The extent of degradation depends on the concentration of chemicals, the level and fluctuations of groundwater level or changes in tide and river levels, or climatic conditions.
The only way to increase the durability of the foundation is to protect the foundation material from the above attacks.
Usually 4 kinds of material are used as foundation material, such as
- timber foundation
- metal foundation
- solid foundation
- brick work foundation
Let us discuss the ways to protect various foundation materials from spoilage.
1. Preservation of Timber Foundation
Wood piles are liable to fungal attack and termites if kept in moist conditions. Wood protection is best achieved by pressure treating the copper arsenic type of waterborne preservative with coal tar creosote.
Molluscans and crustacean borers living in brackish or brackish water on wood piles in marine formations.
Protection may also be provided by concrete prior to stacking in driving, or by ganite mortar after installation.
Concrete can be used in the foundation of the land, either in mixed concrete-wood piles, or under deep piles to groundwater level.
2. metal foundation protection
Steel piles can be given an impervious coating of bitumen, coal tar pitch, synthetic resins. These coatings are not effective and are partially removed. Generally, a sufficient cross-sectional area of steel must be provided to allow dissipation over the useful life of the structure while leaving enough steel to keep the working stress within a safe range. in critical condition; It may be necessary to adopt a system of cathodic protection.
3. Concrete Foundation Protection
Concrete foundations below ground level are liable to be attacked by sulfates in the soil or groundwater. Because of the inhibitory effect of chlorides in sea water, sulfates do not cause a wide range of reactions for ordinary Portland cement concrete. However, it is good practice to use sulfate-resistant cement in reinforced concrete structures submerged in sea water.
High alumina and super sulfate cements provide protection in acidic ground conditions where pH values can be as low as 3.5. However, high alumina cement concrete cannot be used where alkalis are present in strong concentrations.
In severe exposure situations, a dense concrete mix with a water-cement ratio of less than 0.5 should be used. If the ratio is between 0.5 to 0.6, there is a risk of frost attack and above 0.6 the risk becomes progressively higher.
4. Protection of Brick Work Foundation
Bricks with high absorption are responsible for the dissolution of frost. They can absorb sulfates or other aggressive substances from the soil or from coming into contact with the brickwork. In sulphate-rich soils or groundwater, the brick work mortar should be a 1:3 (cement:sand) mixture made of sulphate-resistant cement or under severe conditions with super-sulphated cement.