After the plumber finishes installing the drain pipes for the sinks and toilets in the villa’s floor according to the plan, the area where the pipes were laid is backfilled with soil and thoroughly sprayed with water. An ant termite pesticide is sprayed only on the inner edges of the foundation (ant termite pesticide is available from companies specializing in pest control), after which a thick layer of nylon is laid on the villa’s floor.
The contractor calculates the amount of concrete needed to pour the floor and schedules the pour with the concrete supplier. The villa’s floor concrete (clean mix) should be 250-grade reinforced concrete or as specified in the project specifications, with a thickness of no less than 10 cm. Some owners prefer to use 350-grade reinforced concrete for the pour out of concern for settlement.
The rebar installer will begin laying the reinforcing bars for the floor. Pre-cut 8-mm reinforcing mesh is used, while others prefer to use 10-millimeter rebar—or even thicker—to avoid the risk of floor subsidence, God forbid. The rebar is properly raised off the floor using tile pieces or concrete blocks prepared on-site.
Once the pump arrives on site, the floor is sprayed with water, and the contractor begins the pouring process. The concrete must be leveled using a screed machine; the contractor is prohibited from adding water to the concrete. Some prefer to have workers pour the concrete on-site; however, ready-mix concrete is undoubtedly much better than on-site mixed concrete when there is no site engineer present, especially since it is rare to have a qualified site engineer for a residential villa project.
Three hours after the concrete is poured, it is sprayed with water as if it were raining. Water spraying continues for at least 7 days, twice daily, With this, we have completed all underground work for residential villas without basements. Next week, we will continue with the steps to construct the basement ceiling until we also finish the underground work for residential villas with basements.
Readers" questions?
After flooding the backfill with water and compacting the ground, it became apparent that there are scattered areas that feel spongy; when a bullet passes through or someone walks on them, the ground sinks, but when the person leaves, the ground immediately returns to its normal state?
If the backfill used in the project is clay soil, when it is saturated with water or even when water reaches it in the future—whether from gardens or other sources—this soil is "expansive soil" that is affected and sinks when any heavy object passes over it, then returns to its normal state. and its effect is not limited to subsidence alone; these types of soil may also cause mounds to form in courtyards when exposed to water, whether from sewage system leaks or even rainwater and the like.
In such cases, the backfill must be removed and replaced with high-quality backfill. Removing the backfill is limited to areas where the soil has turned into expansive soil due to the presence of clay lumps in these locations; therefore, care must be taken to use high-quality backfill.
@majedmohaimeed
