Concrete compositions
A concrete which includes in parts by weight: 100 Portland cement; 50 to 200 of a sand having a single grading with a D10 to D90 between 0.063 and 5 mm, or a mixture of sands, the finest sand having a D10 to D90 between 0.063 and 1 mm and the coarsest sand having a D10 to D90 between 1 and 4 mm; 10 to 50 of a particulate, substantially non-pozzolanic material having a mean particle size less than 15 μm; 0.1 to 10 of a water-reducing superplasticizer; and 10 to 30 of water; which concrete is substantially free of silica fume; the concrete having a compressive strength greater than 100 Mpa at 28 days.
1. A concrete which comprises in parts by weight:
100 of Portland cement;
50 to 200 of a sand having a single grading with a D10 to D90 between 0.063 and 5 mm, or a mixture of sands, the finest sand having a D10 to D90 between 0.063 and 1 mm and the coarsest sand having a D10 to D90 between 1 and 4 mm;
10 to 50 of a particulate, substantially non-pozzolanic material having a mean particle size less than 15 μm;
0.1 to 10 of a water-reducing superplasticizer; and
10 to 30 of water;
wherein the concrete is substantially free of silica fume; and wherein the concrete has a compressive strength greater than 100 Mpa at 28 days.
2. A concrete according to claim 1 , comprising quicklime, burnt lime or calcium oxide.
3. A concrete according to claim 1 , wherein the non-pozzolan comprises a ground limestone or ground quartz.
4. A concrete according to claim 1 , comprising a ground limestone, ground quartz or a precipitated calcium carbonate or a mixture thereof.
5. A concrete according to claim 1 , comprising organic or metal fibres.
6. A concrete according to claim 5 , comprising 0.5 to 3.5% of metal fibres by volume relative to the volume of set cement.
7. A concrete according to claim 5 , comprising 2 to 5% of organic fibres by volume relative to the volume of set cement.
8. A concrete according to claim 5 , which has a compressive strength of more than 120 MPa.
9. A cement mixture comprising the materials specified in claim 1 and optionally calcined limestone or calcined dolomite but excluding water and, if it is liquid, superplasticizer.
10. A Method of using a particulate, substantially non-pozzolanic material having a mean particle size less than 15 μm to replace silica fume in the production of a concrete according to claim 1 .
11. A concrete according to claim 6 , which has a compressive strength of more than 120 Mpa.
12. A concrete according to claim 7 , which has a compressive strength of more than 120 Mpa.