Ground Concrete Slabs: the Good, the Bad and the Ugly

Predominantly used as floors and sometimes in roofing systems for multiple story conduction, Sephaku Cement discusses concrete slabs and everything you need to know when using these in your next building project.

Fulfilling a similar purpose to concrete beams, while rarely as thick as supporting concrete beams, concrete floor slabs are made using a steel reinforced framework that offers added Load-bearing strength and assists in reducing damage caused by freeze thaw effects.

While suspended concrete slabs are typically precast, ground concrete slabs are best poured onsite by filling demarcated areas where the sub-grade or foundation has been adequately prepared. Poured to a depth between 15cm and 30cm, onto foundations with a minimum load-bearing capacity of 50 kPa, a key step to fitting concrete floor slabs is ensuring that the sub-grade is prepared to perfection in order to offer a strong and steadfast sub-grade.

So, what if the foundation is less than adequate?

Well prepared foundations on which concrete floor slabs are poured ensure sound footing for load-bearing capacity as well as lasting durability over time. A sub-grade that naturally contains more clay or silt can influence the lasting strength of a concrete slab when coming into contact with moisture, because these soils hold onto water a lot longer than others, the concrete slab is unnecessarily exposed to the added stress of freeze-thaw effects that could otherwise be avoided or at best reduce when the sub-grade is properly prepared.

Another factor to take into account, when pouring a concrete slab onto prepared foundations (which is a recommended practice), the quality of these foundations will determine the concrete slab durability and load-bearing capacity, where foundations are flawed or poorly prepared, this will result in significant damage caused to the concrete slab as well as structural damage to the building.

What are the advantages of concrete floor slabs?

Energy-Efficient: With Energy efficiency being a primary objective in new building construction and concrete slabs offering similar thermal properties to bricks and plaster, they provide a number of thermal advantages and lifestyle benefits;

  • For cooler climates, concrete slabs strategically placed to absorb as much heat from the sun as possible are able to significantly contribute to warmer ambient temperatures of the room in which they are fitted.
  • In hot summer conditions, concrete slabs that are shaded from direct sunlight offer a naturally cooler material compared to others, which will contribute to keeping the temperature of your home comfortably cool.

Lasting Durability: Made to last a lifetime, when concrete floor slabs are poured onto properly prepared foundations, using the correct aggregate and water ratios and are allowed to cure for the appropriate period of time, concrete slabs will stand the test of time with just a little bit of upkeep, maintenance and cleaning.

Optimal Acoustics: An effective way to reduce the transfer of noise, concrete slabs placed between two separate floors of a building offer an excellent sound barrier between upstairs and downstairs floors.

Decorative Finishes: A common misconception is that concrete slabs create a cold and drab feel to a home or place of work which in fact couldn’t be further from the truth. Versatile to a broad range of details, textures, colours and finishes, concrete slabs are by no means limited in their aesthetics.