Concrete Roads
and Their Construction
År: 1920
Serie: Concrete Series
Forlag: Concrete Publications Limited
Sted: London
Sider: 197
UDK: 625.8 Con-gl.
Being a Description of the concrete Roads in the United Kingdom, together with a Summary of the Experience in this Form of Construction gained in Australia, Canada, New Zealand and the United States of America.
Søgning i bogen
Den bedste måde at søge i bogen er ved at downloade PDF'en og søge i den.
Derved får du fremhævet ordene visuelt direkte på billedet af siden.
Digitaliseret bog
Bogens tekst er maskinlæst, så der kan være en del fejl og mangler.
36
CONCRETE ROADS
to an average depth of 7 in., except the portions adjoining exist-
ing kerbs, which were cut out to a depth of 12 in.
At this stage the gas and water companies’ men visited the
site and satisfied themselves as to the necessity for any repairs
to their mains and services before the new work was com-
menced.
The concrete for the lower bed consisted of three parts of local
ballast to the following specification : 1 part of material
passing through a 1-in. screen and retained on |-in. ; 1 part
of material passing through a |-in. screen and retained on a
|-in. ; 1 part of material passing through a }-in. screen and
retained on a 22 screen.
To this was added 1 part sand all through in. screen, and 1 part
Portland cement, complying with British Standard Specification
for slow-setting cement.
The top-course concrete was 1| in. in thickness, and consisted
of one part best granite chippings graded from dust to | in. One
part sand all through & ’n- screen, and one part Portland cement.
The concrete was mixed by hand to a plastic consistency, and
special attention was given to the placing of the top course, which
throughout the entire job was carried along simultaneously
with the putting in of the lower bed or base.
Transverse expansion joints were made in the concrete every
40 ft., and longitudinal expansion joints in the concrete alongside
the kerbs. These were provided for before the concrete was laid
by placing |-in. by 7-in. wrought boards of convenient lengths
and slightly greased with a hard lubricating grease ; the boards
were withdrawn when the concrete had set sufficiently to allow
their being removed without the arrises being destroyed, and the
expansion joints were filled flush with the finished surface of the
concrete with commercial soft pitch.
As soon as the lower course was finished, and while the material
was still plastic, the reinforcement was placed upon it and slightly
pressed into it, the sheets of fabric being overlapped 4 in. at the
sides. While the reinforcement covered the whole area between
the expansion joints, in no case did it extend across them.
As the top-course concrete was laid the surface was immediately
struck off by means of a template resting on one kerb, and one
longitudinal screed, the template being moved over the surface
with a combined longitudinal and transverse motion. Any excess
of material accumulating in front of the template was uniformly