According to the provided reference, when laying readymix concrete, it should be placed on a prepared base consisting of several specific layers.
For laying concrete, specifically readymix concrete as described in the reference, you should prepare a base that includes a well compacted hardcore sub-base, followed by a thin layer of sand, and finally a layer of plastic sheeting or damp proof membrane (dbm).
Preparing the Concrete Base Layers
Creating a suitable base is crucial for the longevity and stability of a concrete slab. The reference outlines a specific sequence of materials to use:
- Sub-Base (Bottom Layer): Start with a well compacted hardcore sub-base. Hardcore typically consists of crushed stone or recycled construction materials. Proper compaction is essential and can be achieved using tools like a tamper, roller, or mechanical compactor.
- Levelling Layer: On top of the compacted hardcore, spread a thin layer of sand. This layer helps to provide a smooth, level surface.
- Barrier Layer (Top Layer): The final layer before pouring the concrete is a layer of plastic sheeting or a damp proof membrane (dbm). This membrane acts as a barrier against moisture rising from the ground, which can otherwise affect the concrete.
Therefore, the concrete is ultimately laid directly onto the plastic sheeting or damp proof membrane, which sits on the sand layer covering the compacted hardcore sub-base.
Layer Structure for Laying Concrete
To visualize the base layers from the ground up, consider the following structure:
- Ground / Existing Subgrade
- Well Compacted Hardcore Sub-Base (Requires compaction with tamper, roller, or mechanical compactor)
- Thin Layer of Sand (Applied on top of the compacted hardcore)
- Layer of Plastic Sheeting or Damp Proof Membrane (dbm) (Applied on top of the sand)
- Readymix Concrete (Poured directly onto the membrane)
This layered approach, starting with a well compacted hardcore sub-base and including sand and a membrane as described in the reference, provides a stable and protective foundation for the concrete slab.
