Concrete mixture and method of forming the same
A concrete mixture for forming a breathable concrete. The mixture comprises aggregate particles and a paste comprising water, cement or cement substitute, and plasticizer. The plasticizer controls the viscosity of the paste such that the paste forms a substantially uniform layer coating the particles, with the coated particles in contact, while allowing spaces to be retained there between. These spaces interconnect forming channels through the concrete, allowing air to permeate there through such that the concrete exhibits good dynamic insulation properties, whist retaining structural strength.
1. A concrete mixture for forming a breathable concrete, the mixture comprising:
aggregate particles;
a paste comprising water, cement or cement substitute, and plasticizer;
the plasticizer controlling viscosity of the paste such that the paste forms a substantially uniform layer coating the particles, which with the coated particles in contact allows spaces to be retained there between, such spaces being interconnectable to form channels through the mixture;
wherein the average diameter of the aggregate particles is in the range of 1 mm to 8 mm; and wherein the water to cement ratio in the paste is in the range 0.15 to 0.4 by weight; and wherein a degree of filling of the paste to the aggregate particles is in the range of 30 to 80%; and wherein the degree of filling is the volumetric ratio of the paste to the spaces formed between the aggregate particles.
2. A concrete mixture according to claim 1 , wherein the average diameter of the aggregate particles is in the range of 2 mm to 5 mm.
3. A concrete mixture according to claim 1 , wherein the plasticizer is a superplasticizer.
4. A concrete mixture according to claim 1 , wherein the degree of filling of the paste to the aggregate particles is in the range 50 to 60%.
5. A concrete mixture according to claim 1 , wherein the mixture comprises 0.1-1.5% by weight of plasticizer.
6. A concrete mixture according to claim 5 , wherein the mixture comprises 0.2-0.8% by weight of plasticizer.
7. A concrete mixture according to claim 1 , wherein the plasticizer is a melamine formaldehyde series plasticizer.
8. A concrete mixture according to claim 7 , wherein the plasticizer is melamine-formaldehyde condensate.
9. A concrete mixture according to claim 1 , wherein the plasticizer is napthalene-formaldehyde condensate or polycarboxylate-ether.
10. A concrete mixture according to claim 1 , wherein the plasticizer is any high-range water reducer.
11. A concrete mixture according to claim 1 , wherein the cement is Portland cement.
12. A concrete mixture according to claim 1 , wherein the aggregate particles have packing densities of 700 to 2000 kg/m 3 .
13. A concrete mixture according to claim 1 , wherein the aggregate particles have packing densities of 700 to 1600 kg/m 3 .
14. A concrete mixture according to of claim 1 , wherein the aggregate particles are fly ash aggregate having packing densities of 700 to 800 kg/m 3 .
15. A concrete mixture according to claim 1 , wherein the aggregate particles are paper ash aggregates having packing densities below 700 kg/m 3 .
16. A concrete mixture according to claim 1 , wherein the aggregate particles have packing densities of less than 1000 kg/m 3 .
17. A concrete mixture according to claim 1 , wherein the aggregate particles have a natural packing density ratio of 0.50-0.55,
wherein the natural packing density ratio equals V/M
where
V is the volume of aggregate used to fill a mold without compaction or vibration of the aggregate, and
M is the geometric volume of the mold.
18. A method of forming a concrete mixture for forming a breathable concrete, comprising the steps of:
mixing aggregate particles and a paste comprising water, cement or cement substitute, and plasticizer,
said plasticizer controlling viscosity of the paste such that the paste forms a substantially uniform layer coating the particles, which with the coated particles in contact allows spaces to be retained there between, such spaces being interconnectable to form channels through the mixture;
wherein the average diameter of the aggregate particles is in the range 1 mm to 8 mm; and wherein the cement to water ratio is the paste is in the range 0.15 to 0.4 by weight; and wherein a degree of filling of the paste to the aggregate particles is in the range of 30 to 80%; and wherein the degree of filling is the volumetric ratio of the paste to the spaces formed between the aggregate particles.
19. A method according to claim 1 , wherein the aggregate particles have a natural packing density ratio of 0.50-0.55,
wherein the natural packing density ratio equals V/M
where
V is the volume of aggregate used to fill a mold without compaction or vibration of the aggregate, and
M is the geometric volume of the mold.
20. A method according to claim 1 , further comprising the step of allowing the mixture to set.