One of the most valuable members of the Dawson Group of companies is Sansan Installations Ltd., leading gunite contractor in British Columbia.
General manager of the company, T.T. (Terry) Learmouth works closely with Vice-president Lloyd Blain and through their team-work and collaboration with engineering consultants, Sansan has developed a revolutionary shotcrete method to shore building excavations.
“In fact,” says Learmouth, “guniting is being replaced by shotcreting, except for special applications, and Sansan is pioneering the shotcrete method into more and more fields in the construction industry.”
Shotcrete is a pneumatically applied concrete product consisting of large aggregate up to three-quarter inch, and sand and cement. Fast acting chemicals are added, giving the product structural properties which never existed in gunite.
One of the main advantages of shotcrete is its extremely high early compressive strength. Normal seven-day strength of conventional concrete is reached within 24 hours.
Learmouth said fluctuant strength of concrete is twice as great as that in conventionally poured concrete and shotcrete also prevents erosion by water and air.
“These advantages have opened up a great number of applications in primary and secondary ground support in excavations and tunnels,” said Learmouth.
Shotcrete was first used in Europe and it was through visits to installations in Italy, Germany, Switzerland and Austria, by Learmouth, followed by extensive research and experimentation, that Sansan obtained the patent for the method for Canada and the United States.
Learmouth, who rose to his present position through the ranks as a carpenter, said the European method was refined and modified to meet requirements here, and the company was awarded its first major contract for shotcrete in 1966, applying the lining in the 2.5-mile CNR tunnel through Burnaby to the Second Narrows crossing.
“Experience gained on that job,” said Learmouth, “has benefitted tunnel experts throughout North America.
“And, since then, Sansan has established itself as the leader in shotcrete work in the western hemisphere.”
In Vancouver the system has been used in excavations for such projects as Pacific Centre, Denman Place and the Guinness office tower.
Granduc Mines Ltd., also awarded Sansan the shotcrete contract for its 11-mile tunnel. It was completed in 1968, opening the company’s copper deposit in northern British Columbia.
Shotcrete Engineering Ltd., an affiliate of the Dawson Group, has been formed to do the design and engineering work required for each project and to promote the system throughout the western hemisphere. The firm holds the patents for Canada and the U.S.
E.E. Mason of Domage, Mason, Stewart Ltd., is president of Shotcrete Engineering Ltd.
In an effort to diversify, Sansan, Inc., was incorporated in the State of Delaware to carry out shotcrete work in the Eastern U.S. The company’s headquarters is in Silver Spring, Md., about eight miles from Washington, D.C.
The Sansan shoring system has been used on the transit authority’s freeway system in Washington, D.C. and extensive tunnel restoration projects have been carried out for the Norfolk and Western Railway in West Virginia and Ohio.
Experimental projects have been completed in the coal mines of Pennsylvania aimed at increasing safety. The system is being used to support weak sections in the mines where vibrations and air frequently cause the tunnels to collapse.
Shotcrete Equipment and Supply Ltd. is another Dawson company formed to handle the Mayco line of shotcrete equipment and chemical accelerators for Canada, the U.S. and Mexico.
The equipment is manufactured in Switzerland. It is recognized as the best of its kind in the world. The company holds the exclusive franchise for its use in the Western Hemisphere. The company also provides technical assistance in the use of the equipment.
Sansan Installations Ltd., a wholly-owned subsidiary of Dawson Construction Ltd., originally was a terrazzo company doing terrazzo floors for hospitals and ships’ decking, as well as building swimming pools.
The company expanded into guniting and became the leading contractor in the province. Most important contract ever handled was guniting at the Peace River power project- the largest guniting job in North America.
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