Pavers and block composite materials and methods of preparation thereof
The invention provides novel paving stones and construction block composite materials and methods for preparation thereof. The paving stones and construction block composite materials can be readily produced from widely available, low cost precursor materials by a production process that involves compacting in a mold that is suitable for large-scale production. The precursor materials include calcium silicate, for example, wollastonite, and particulate filler materials which can comprise silicon dioxide-rich materials. Additives can include calcium carbonate-rich and magnesium carbonate-rich materials. Various additives can be used to fine-tune the physical appearance and mechanical properties of the composite material, such as colorants such as particles of colored materials, such as, and pigments (e.g., black iron oxide, cobalt oxide and chromium oxide). These paving stones and construction block composite materials exhibit visual patterns similar to stone as well as display compressive strength and water absorption equal to or better than that of stone.
1. A composite construction material, comprising:
a plurality of bonding elements, wherein each bonding element comprises:
a core comprising primarily calcium silicate,
a silica-rich first or inner layer, and
a calcium carbonate-rich second or outer layer; and
a plurality of filler particles,
wherein the plurality of bonding elements and the plurality of filler particles together form one or more bonding matrices and the bonding elements and the filler particles are configured to be bonded together as a result of a reaction in which an atmosphere comprising more than 50% carbon dioxide is present for about 1 hour to about 80 hours, wherein the composite construction material has a compressive strength in the range of 50 MPa to 300 MPa.
2. The composite construction material of claim 1 , wherein the bonding elements and the filler particles are configured to be bonded together as a result of a reaction in which an atmosphere comprising more than 80% carbon dioxide is present.
3. The composite construction material of claim 1 , further comprising a colorant.
4. The composite construction material of claim 1 , wherein the plurality of bonding elements have a median particle size in the range from about 5 μm to about 100 μm.
5. The composite construction material of claim 1 , wherein the filler particles are made from a silicon dioxide-rich material.
6. The composite of claim 1 , wherein the plurality of filler particles comprise one or more of quartz, mica and feldspar.
7. The composite construction material of claim 1 , wherein the plurality of bonding elements are chemically transformed from ground wollastonite.
8. The composite construction material of claim 1 , wherein the plurality of bonding elements are chemically transformed from a precursor calcium silicate other than wollastonite.
9. The composite construction material of claim 1 , wherein the plurality of bonding elements are chemically transformed from a precursor calcium silicate comprising one or more of aluminum, magnesium and iron.
10. The composite construction material of claim 3 , wherein the colorant comprises one or more of iron oxide, cobalt oxide and chromium oxide.
11. The composite construction material of claim 1 , wherein the weight ratio of bonding elements:filler particles is about 8-50:50-92.
12. The composite construction material of claim 3 , wherein the colorant is present in an amount up to about 10% by weight.
13. The composite construction material of claim 1 , wherein the plurality of bonding elements are prepared by chemical transformation from ground wollastonite by reacting it with CO 2 via a controlled hydrothermal liquid phase sintering process.
14. The composite construction material of claim 1 , wherein the plurality of bonding elements are prepared by chemical transformation from the precursor calcium silicate other than wollastonite by reacting it with CO 2 via a controlled hydrothermal liquid phase sintering process.
15. The composite construction material of claim 1 , having water absorption of less than about 10%.
16. The composite construction material of claim 1 , exhibiting a visual pattern similar to stone.
17. The composite construction material of claim 1 , wherein the weight ratio of bonding elements:filler particles is about 5-50:50-95.
18. The composite construction material of claim 1 , wherein the bonding elements and the filler particles are configured to be bonded together as a result of a reaction in which an atmosphere comprising more than 50% carbon dioxide is present for about 5 hours to about 70 hours.
19. The composite construction material of claim 1 , having a flexural strength of 5 MPa to 30 MPa.
20. The composite construction material of claim 1 , wherein the plurality of bonding elements and the filler particles are configured to be bonded together as a result of a reaction at a temperature in the range from about 60° C. to about 110° C. for about 15 hours to about 70 hours under an atmosphere of water and CO 2 having a pressure in the range from ambient atmospheric pressure to about 30 psi.
21. The composite construction material of claim 1 , wherein the plurality of bonding elements are chemically transformed from ground wollastonite having a median particle size from about 5 μm to about 50 μm, a bulk density from about 0.6 g/ml to about 0.8 g/ml (loose) and about 1.0 g/ml to about 1.2 g/ml (tapped), and a surface area from about 1.5 m 2 /g to about 2.0 m 2 /g.
22. The composite construction material of claim 21 , wherein the filler particles comprise an SiO 2 -based material having a median particle size of 5 μm to 7 mm.