Synthetic aggregate from waste materials

Patent metadata

Field	Value
Publication number	US-2018179107-A1
Application number	US-201615389357-A
Country	US
Kind code	A1
Filing date	Dec 22, 2016
Priority date	Dec 22, 2016
Publication date	Jun 28, 2018
Grant date	—

Abstract

Synthetic aggregates are fabricated from greater than approximately 70 wt % waste starting materials. Starting materials may be selected from granulated ground blast furnace slag, waste concrete fines, or sewage sludge ash, and mixtures thereof. The starting materials are bound together by a hydraulic cementitious binder either added to the starting materials or formed in situ. The waste starting materials, binder, and water are formed into pellets and subjected to a hydraulic reaction and carbonation in an atmosphere of greater than approximately 50% carbon dioxide at temperatures less than approximately 100° C. The resulting synthetic aggregate has a crush strength after a period of hardening equal to or greater than approximately 0.5 MPa.

First claim

1 . A synthetic aggregate fabricated from greater than approximately 70 wt % waste starting materials selected from granulated ground blast furnace slag, recycled concrete waste fines, or sewage sludge ash, and mixtures thereof, the starting materials being bound together by a hydraulic cementitious binder, the waste starting materials, binder, and water having been formed into pellets and subjected to a hydraulic reaction and carbonation in an atmosphere of greater than approximately 50% carbon dioxide at temperatures less than approximately 100° C., the aggregate having a crush strength after a period of hardening equal to or greater than approximately 0.5 MPa.

2 . The synthetic aggregate of claim 1 wherein the binder is selected from Portland cement or fresh concrete waste.

3 . The synthetic aggregate of claim 1 wherein the carbonation occurs while the pellets are being formed and the density is less than about 1200 kg/m 3 .

4 . The synthetic aggregate of claim 1 wherein the carbonation occurs after the pellets are formed and the density is above about 1700 kg/m 3 .

5 . The synthetic aggregate of claim 1 wherein the aggregate is fabricated from the waste starting materials, binder, water and hydrogen peroxide and the density is less than 1200 kg/m 3 .

6 . The synthetic aggregate of claim 1 wherein the water absorption is less than approximately 20%.

7 . The synthetic aggregate of claim 6 wherein the starting material is sewage sludge ash and the pellets are treated with a silane-based agent.

8 . The synthetic aggregate of claim 1 wherein the waste starting material is sewage sludge ash in an amount greater than 75 wt %.

9 . The synthetic aggregate of claim 1 wherein the waste starting material is recycled concrete waste fines in an amount greater than 75%.

10 . The synthetic aggregate of claim 1 further comprising an additional material selected from fly ash, lime, kaolin and silica fume.

11 . A concrete product including the synthetic aggregate of claim 1 .

12 . A concrete product including the synthetic aggregate of claim 3 .

13 . A concrete product including the synthetic aggregate of claim 4 .

14 . A concrete product including the synthetic aggregate of claim 5 .

15 . A synthetic aggregate fabricated from greater than approximately 90 wt % ground granulated blast furnace slag, being bound together by one or more reaction products of a combination of water, alkali and slag, the synthetic aggregate having been formed into pellets and subjected to carbonation in an atmosphere of at least approximately 50% carbon dioxide at temperatures less than approximately 100° C., the aggregate having a crush strength equal to or greater than approximately 0.5 MPa.

16 . The synthetic aggregate of claim 15 wherein the carbonation occurs while the pellets are being formed and the density is less than about 1200 kg/m 3 .

17 . The synthetic aggregate of claim 15 wherein the carbonation occurs after the pellets are formed and the density is above about 1700 kg/m 3 .

18 . The synthetic aggregate of claim 15 wherein the aggregate is fabricated from the waste starting materials, water and hydrogen peroxide and the density is less than 1200 kg/m 2 .

19 . The synthetic aggregate of claim 15 further comprising an additional material selected from fly ash, lime, kaolin and silica fume.

20 . A concrete product including the synthetic aggregate of claim 15 .

Assignees

• Nano & Advanced Materials Inst Ltd

Inventors

• Gao Yan
• Zhu Honggang
• Yan Yifei
• Li Bo
• Sham Man Lung
• Ling Tung-Chai

Classifications

• C04B20/04

  Heat treatment · CPC title

• C04B40/0039 Primary

  Premixtures of ingredients · CPC title

• C04B18/167 Primary

  Recycled materials, i.e. waste materials reused in the production of the same materials · CPC title

• C04B18/141

  Slags · CPC title

• C04B28/04

  Portland cements · CPC title