Low embodied energy wallboards and methods of making same
View Patent ↗Wallboards, as well as other building materials, are produced by methods which use significantly reduced embodied energy, generating far less greenhouse gases when compared with the energy used to fabricate gypsum wallboard. A novel cementitious core, consisting in one embodiment of post-industrial waste such as slag and combined with pH modifiers, provides a controlled exothermic reaction to create a gypsum-wallboard-like core which can be wrapped in a selected material such as recycled paper and manufactured on a conveyor system to appear, weigh and handle similar to gypsum wallboard, but without the large amounts of energy required to make gypsum wallboard. The manufacturing process results in lower greenhouse gas emissions than the processes used to make gypsum wallboard.
1. A structure comprising:
greater than about 50% (w/w) of post-industrial waste products including slag and kiln dust, wherein the post-industrial waste products include less than approximately 1% gypsum content; and
at least one alkali activating agent.
2. The structure of claim 1 , wherein said alkali activating agent comprises one or more materials selected from the group consisting of: calcium oxide, magnesium oxide, potassium hydroxide, sodium hydroxide, calcium hydroxide, calcium carbonate, potassium carbonate, sodium carbonate, sodium sesquicarbonate, sodium silicate, calcium silicate, magnesium silicate or calcium aluminate.
3. The structure of claim 1 , wherein the post-industrial waste products comprise about 60 percent (60%) or more by weight of the total weight of said structure.
4. The structure of claim 1 , further comprising fibers selected from the group consisting of biofibers, a thermoplastic polymer, fiberglass, cellulose and recycled petroleum waste.
5. The structure of claim 1 , further comprising a filler of foam.
6. The structure of claim 1 , further comprising paper on one or both sides.
7. The structure of claim 1 , further comprising water.
8. A method of fabricating a material for use in a building or building infrastructure, comprising:
forming a dry mix comprising (i) greater than about 50% (w/w) of post-industrial waste products including slag and kiln dust, wherein the post-industrial waste products include less than approximately 1% gypsum content, and (ii) at least one alkali activating agent selected from the group consisting of calcium oxide, magnesium oxide, potassium hydroxide, sodium hydroxide, calcium hydroxide, calcium carbonate, potassium carbonate, sodium carbonate, sodium sesquicarbonate, sodium silicate, calcium silicate, magnesium silicate and calcium aluminate;
adding water to said dry mix to form an initial slurry in a slurry line; and
allowing the initial slurry to set.
9. The method of claim 8 , wherein said initial slurry is allowed to set without the application of heat.
10. The method of claim 8 , further comprising cutting the set slurry to a desired shape.
11. The method of claim 8 , further comprising adding a retarder material to the slurry to increase the time taken for the slurry to set.
12. The method of claim 8 , further comprising adding an accelerator material to the slurry to decrease the time taken for the slurry to set.
13. The method of claim 8 , further comprising pouring the slurry into a mold of a given shape.
14. The structure of claim 1 , wherein the post-industrial waste products further include fly ash.