Aggregate for use in making structural elements
CA 2038207 A1 · Owner: Derby-Lewis, Gerald A. · Inventors: Derby-Lewis, Gerald A.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A method of producing a lightweight building material, such as an aggregate, comprises mixing clay powder with a high percentage of coal dust to create areas of coal within the mixture which represent a desired density of voids, pelletising the mixture in the case of aggregate, and firing it to burn off the coal and harden the clay. The burning off of the coal leaves lightweight void areas within the hardened clay to form a lightweight building material or aggregate.
Read the whole patent
Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.
Why it's free to use
- Filed March 14, 1991. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended March 14, 2011.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by March 14, 2013.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
Timeline
Timeline From CIPO dates
Sources & verification
Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.