How do you pour concrete that will never crack?
Technically, concrete mixtures are placed not poured. Due to the volume changes that concrete experiences as it cures and it’s relatively low tensile strength it is unlikely that it will never crack. Concrete requires very little water to hydrate water added to provide workability, otherwise known as water of convenience has to leave the concrete as it hardens, causing s volume change.
The hydration process is exothermic causing the concrete to increase in temperature and volume. As the concrete cools to service temperatures or lower the thermal shrinkage can cause cracking. That is why sprinkling a surface with water is not necessarily the best curing method, especially if it causes rapid cooling at the surface.
I’ve poured a few slabs with competent help. Here’s what I learned:
- The ground needs to be well prepared and compact. Try not to disturb the bottom of any trenches or holes you dig for footers. Leave them as compact as possible after removing loose soil. Compact the ground as needed and lay a well-compacted bed of base course above them.
- Reinforce with well-tied rebar and mesh. Reinforce thick footers in all three dimensions.
- Build a great form and make sure it’s tight and level.
- Use a mix/design that’s suitable in strength to your demands. For my outbuilding, I poured a slab of very high PSI concrete with a continuous, reinforced footer 18” deep all around and mesh reinforcement across the slab. The center is 5” thick.
- Let a knowledgeable tradesperson finish the slab after screeding.
- Cut control cracks as recommended by code and at all inside corners if the slab was poured around anything.
- Keep the slab wet while curing to manufacturer recommendations.
- Wait for the slab to cure per manufacturer specs before loading it.
That’s about the best you can do to avoid cracks. By these methods, you can pour concrete, that will never cracks.