Structural lightweight concrete with superior thermal insulation
A structural lightweight concrete composition comprising cement, a fine aggregate such as sand, a natural coarse aggregates, such as limestone, scoria or perlite or mixtures thereof, a synthetic coarse aggregate comprising a polymeric material, such as polypropylene beads, an industrial waste byproduct in the form of fine particles, such as silica fume or heavy oil ash, a superplasticizer, such as a polycarboxylate ether and water demonstrating lower thermal conductivity and sufficient compressive strength. Concrete products made therefrom and methods for producing such products are also provided.
1. A structural lightweight concrete composition, comprising:
cement;
a fine aggregate;
a natural coarse aggregate;
spherical polymeric beads;
an industrial waste byproduct in the form of fine particles;
a superplasticizer; and
water;
wherein the average particle size of the fine aggregate and the industrial waste byproduct is less than or equal to 1 mm and the average particle size of the spherical polymeric beads and the natural coarse aggregate is greater than 1 mm;
wherein the weight ratio of water to cement is in the range of 0.33 to 0.8 and is sufficient to affect hydraulic setting of the cement; and
wherein the spherical polymeric beads have a specific gravity of 0.8-0.95.
2. The structural lightweight concrete composition of claim 1 , wherein the spherical polymeric beads are spherical polypropylene beads with an average particle size of 4-15 mm.
3. The structural lightweight concrete composition of claim 1 , which has a weight percentage of the spherical polymeric beads ranging from 2-15% relative to the total weight of the composition.
4. The structural lightweight concrete composition of claim 1 , wherein the cement is present in the composition at 300-500 kg/m 3 .
5. The structural lightweight concrete composition of claim 1 , which has a weight percentage of cement ranging from 20-30% relative to the total weight of the composition.
6. The structural lightweight concrete composition of claim 1 , wherein the fine aggregate is sand with an average particle size of less than 700 μm.
7. The structural lightweight concrete composition of claim 1 , which has a weight percentage of the fine aggregate ranging from 15-30% relative to the total weight of the composition.
8. The structural lightweight concrete composition of claim 1 , wherein the natural coarse aggregate is at least one selected from the group consisting of limestone, perlite, and scoria.
9. The structural lightweight concrete composition of claim 1 , which has a weight percentage of the natural coarse aggregate ranging from 20-45% relative to the total weight of the composition.
10. The structural lightweight concrete composition of claim 1 , wherein the natural coarse aggregate comprises crushed limestone having an average particle size in the range of 1-20 mm.
11. The structural lightweight concrete composition of claim 1 , wherein the industrial waste byproduct is at least one selected from the group consisting of silica fume and heavy oil ash.
12. The structural lightweight concrete composition of claim 1 , which has a weight percentage of the industrial waste byproduct in the form of fine particles ranging from 0.5-10% relative to the total weight of the composition.
13. The structural lightweight concrete composition of claim 1 , wherein the superplasticizer is a polycarboxylate ether.
14. The structural lightweight concrete composition of claim 1 , which has a weight percentage of the superplasticizer ranging from 0.1-2.0% relative to the total weight of the composition.
15. The structural lightweight concrete composition of claim 1 , which has a weight percentage of water ranging from 10-20% relative to the total weight of the composition.
16. The structural lightweight concrete composition of claim 1 , which has a 28-day unit weight in the range of 1600-1900 kg/m 3 after setting.
17. The structural lightweight concrete composition of claim 1 , which has a compressive strength in the range of 20-26 MPa after setting.
18. The structural lightweight concrete composition of claim 1 , which has a thermal conductivity in the range of 0.3-0.7 W/(m·K) after setting.
19. A method for producing a cast concrete product comprising the structural lightweight concrete composition of claim 1 , the method comprising:
mixing the cement, the fine aggregate, the natural coarse aggregate, the spherical polymeric beads and the industrial waste byproduct in the form of fine particles to form a solid cement mixture;
adding water and a superplasticizer to the cement mixture to affect hydraulic setting while maintaining a slump in the range of 50-100 mm to form a fluid concrete mixture;
casting the concrete mixture in a predetermined shape by placing the fluid concrete mixture in a mold to produce a cast concrete product after setting.
20. A cast concrete product comprising the structural lightweight concrete composition of claim 1 .