Durable concrete and method for producing the same
A concrete mix for producing freeze-thaw durable concrete having enhanced strength properties, like compressive strength, abrasion resistance, impact strength, toughness, is disclosed. The novel concrete mix contains deformable solid elements in place of 4-8% entrained air for good durability of concrete under freeze-thaw cycles.
1. A concrete mix for producing a freeze-thaw durable concrete, comprising cement, inorganic, hollow, spherical, deformable solid elements, which elements are deformable by crushing at a pressure of <1000 psi, and optionally water, wherein said inorganic deformable solid elements are either included in said concrete mix in a dry state, or mixed with said cement at the time of preparing a wet concrete mix, are present at a level of less than or equal to about 2 vol % and 1.56 wt % relative to the volume of said wet concrete mix or a green concrete or a subsequently hardened concrete formed therefrom, or less than 1.7 wt % in the dry state based on the total weight of all dry materials, and have a maximum dimension of less than about 300 micrometers.
2. The concrete mix of claim 1 , further comprising sand, aggregates, admixtures, or reinforcing fibers or combinations thereof.
3. The concrete mix of claim 1 , wherein a total deformable space of said inorganic deformable solid elements is at least 9% of capillary pores volume, wherein the capillary pores volume is equal to the volume of water in excess of 36% by weight of cement in wet concrete mix.
4. The concrete mix of claim 1 , wherein the total volume of said deformable elements is sufficient to accommodate expansion caused by water freezing in capillary pores of said subsequently hardened concrete during a freezing event.
5. The concrete mix of claim 1 , wherein water is present at a water-to-cement weight ratio in said wet concrete mix of at least about 26%.
6. The concrete mix of claim 5 , wherein the water-to-cement weight ratio in said wet concrete mix is 26 to 40%.
7. The concrete mix of claim 5 , wherein water is present at a water-to-cement weight ratio in said wet concrete mix from about 40% to about 60%.
8. The concrete mix of claim 2 , wherein said admixtures include one or more of retarders, accelerators, plasticizers, fillers, silica fumes, fly ash, other pozzolanic materials or combinations thereof.
9. The concrete mix of claim 1 , wherein said inorganic deformable solid elements have a rigid shell.
10. The concrete mix of claim 9 , wherein said inorganic deformable solid elements are made of materials selected from the group of glass, ceramic and silica and combinations thereof.
11. The concrete mix of claim 10 , wherein said inorganic deformable solid elements are cenospheres.
12. The concrete mix of claim 1 , wherein said inorganic deformable solid elements are glass spheres having rigid shells and a crush strength of <1000 psi.
13. The concrete mix of claim 1 , wherein the deformable solid elements have diameters from about 10 micrometers to about 200 micrometers.