The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 06, 1988
Filed:
Feb. 19, 1987
Hochtief Aktiengesellschaft Vorm. Gebr. Helfmann, Essen, DE;
Abstract
An apparatus for making a tunnel lining from concrete in a single operation with a tunnel excavator comprises a tunnel lining form consisting of a plurality of tunnel lining form segments and a form front adjacent the tunnel excavator and a tunnel lining circular space between the form and the ground. The concrete is selected so that it remains workable for more than two hours at a temperature of about 20.degree. C. but sets to a nonworkable state after 10 to 30 minutes upon heating to a temperature in the range of substantially 40.degree. C. to substantially 70.degree. C. The concrete is heated in a pipe section proximal to the compartment into which it is introduced by direct introduction of electrical energy into the pipe section.