Water-cured concrete made with Portland cement is capable of hardening even when submerged in water. This is due to the cement particles being hydrated, which is a chemical reaction between the cement and water. The biggest challenge when pouring concrete underwater is movement, as it can cause the cement paste that holds the sand and gravel together to be removed. To prevent this, it is important to keep the water calm and cover the concrete with sheets, using something heavy such as bricks or rocks to secure them.
Gravel is especially important in clay soils as it helps with drainage and prevents water from accumulating under the concrete slab. To ensure optimal strength and durability, it is necessary to keep the concrete moist during the curing period. This can be done by creating temporary berms around the new concrete slab and flooding the interior area with water up to one foot (30.48 cm).When building a bridge or pier, concrete foundations are often poured through large tubes to the bottom of the ocean or river. The chemical hydration reaction that allows microscopic Portland cement crystals to grow and interconnect all the sand and gravel together continues to occur for days, weeks and months after concrete is poured and needs water to complete the chemical reaction.
Mixtures are specific ingredients other than aggregate, portland cement and water that are added before or during mixing. Still, others penetrate the concrete to form a permanent sealant that waterproofs the concrete and gives it a freshly poured look. It is important to wait for concrete to dry before covering it or taking precautions to prevent the migration of water or water vapor to other building materials. This will help ensure that the drying process goes smoothly and that the concrete will reach its final position without falling through the water.
