August_1965 — Page 32

Ltd. Special marble saws, handling equipment and forms were employed along with modern techniques for controlling concrete performance.

An important control measure was the use of a carefully selected water- reducing, set-controlling admixture to produce rapid strength gain to meet a 24 hour production schedule. Also employed was an air-entraining ad- mixture to further increase plasticity in the no-slump mix for placement in the forms, and in the bonding grooves cut into the 400 pieces of marble that face each panel.

Although the panels were original- ly designed for attachment to the walls, their precision manufacture furnished accurate vertical alignment to permit their use as exterior forms.

the

This produced three specific bene- fits. First, it cut costs by eliminating half the normal formwork and allow- ing faster placement. Secondly, it assured better anchorage for panels than conventional attachment methods. Finally, it increased safety since workmen had access from in- side the building when panels were positioned.

Concrete was placed through three Torcnto winters. The council cham- ber dome, most critical of all the concreting operations, was built dur- ing cold weather. It is a 155 ft. diameter dome with a thickness vary-

66

ing from 10 in. to 4 in., yet by the use of admixtures and air entraining agents, slump and setting time were precisely controlled and no difficul- ties were encountered.

Reproduced from Concrete 65. A publication of Master Builders

Overal view dramatizes total exposure of concrete. Precast, textured elements are combined with smooth-form finishes and acid-etched concrete.

Conical support for the clear span roof of the council chamber

Far East Architect & Builder August, 1965