LWC
Content
Lightweight Concrete Made From Natural (p όmez ) and Manufactured Vesicular Aggregates By
Ted Bremner Professor Emeritus & Honorary Research Professor University of New Brunswick, Fredericton, NB, Canada Ecuador January 2012 1
Natural Vesicular Aggregates • Vesicular aggregates such as pumice and scoria have been used since about 273 B.C. to make durable marine structures. • On the west coast of Italy, at Cosa, the Romans went 40 km inland to get a volcanic lightweight rock, even though normalweight sand and gravel were readily available on the beach. 2
Port of Cosa on the West Coast of Italy 3
4
Location of Volcanic Aggregates
5
Manufactured Vesicular Aggregates • In 1918 Steven Hayde patented a process of expanding shale, clay or slate in a rotary kiln. • This product was used to make the U.S. Selma – a lightweight concrete ship used in World War I. • The method of manufacture and microstructure of the aggregate produced then is essentially unchanged to this day. So good long-term durability is assured. 6
7
Bank of America, Charlotte, N.C., U.S.A.
47th Floor – 50 MPa
8
• In 1967, using expanded clay RHOBACK Technologies of Germany succeeded in achieving full control over grain size, density, compressive strength and spherical shape with bulk densities ranging from 325 to 800 kg/m 3.
9
CANMET Specimens at Treat Island Marine Exposure Site 10
Non Structural Uses For Vesicular Aggregates With Particular Applications For Pumice 1) Low Density Granular Fill Used to repair slope failures on highways. Lightweight aggregates have a high angle of internal friction. Fill over low load bearing soil – load balancing. 11
2) Filter Beds For treatment of municipal waste. Used where bacterial film has to anchor and develop.
12
3) Arrester Beds At end of airport runways, automobile raceways, and high-speed highways in mountainous regions.
13
4) Backfilling around Pipes, Tunnels and Buildings High insulating aggregates reduce depth needed to bury pipes in cold climates. Reduces lateral and vertical stresses on embedments by 50%. 14
5) Horticultural Growing Medium Ideal material for “green roofs”. Highly absorbent aggregates provide a slow release of moisture and fertilizer.
15
6) Refractor Use Can be used to reline furnaces when combined with stainless steel fibres and plastic fibres. The latter allows steam to escape without explosive spalling.
16
• NOTE: All Six Non Structural Uses can more effectively be accomplished with the lighter pumic aggregates on the Pacific Rim of South America. Thank you [email protected] http://www.unb.ca/civil/bremner/bremner.htm
17
Ted Bremner Professor Emeritus & Honorary Research Professor University of New Brunswick, Fredericton, NB, Canada Ecuador January 2012 1
Natural Vesicular Aggregates • Vesicular aggregates such as pumice and scoria have been used since about 273 B.C. to make durable marine structures. • On the west coast of Italy, at Cosa, the Romans went 40 km inland to get a volcanic lightweight rock, even though normalweight sand and gravel were readily available on the beach. 2
Port of Cosa on the West Coast of Italy 3
4
Location of Volcanic Aggregates
5
Manufactured Vesicular Aggregates • In 1918 Steven Hayde patented a process of expanding shale, clay or slate in a rotary kiln. • This product was used to make the U.S. Selma – a lightweight concrete ship used in World War I. • The method of manufacture and microstructure of the aggregate produced then is essentially unchanged to this day. So good long-term durability is assured. 6
7
Bank of America, Charlotte, N.C., U.S.A.
47th Floor – 50 MPa
8
• In 1967, using expanded clay RHOBACK Technologies of Germany succeeded in achieving full control over grain size, density, compressive strength and spherical shape with bulk densities ranging from 325 to 800 kg/m 3.
9
CANMET Specimens at Treat Island Marine Exposure Site 10
Non Structural Uses For Vesicular Aggregates With Particular Applications For Pumice 1) Low Density Granular Fill Used to repair slope failures on highways. Lightweight aggregates have a high angle of internal friction. Fill over low load bearing soil – load balancing. 11
2) Filter Beds For treatment of municipal waste. Used where bacterial film has to anchor and develop.
12
3) Arrester Beds At end of airport runways, automobile raceways, and high-speed highways in mountainous regions.
13
4) Backfilling around Pipes, Tunnels and Buildings High insulating aggregates reduce depth needed to bury pipes in cold climates. Reduces lateral and vertical stresses on embedments by 50%. 14
5) Horticultural Growing Medium Ideal material for “green roofs”. Highly absorbent aggregates provide a slow release of moisture and fertilizer.
15
6) Refractor Use Can be used to reline furnaces when combined with stainless steel fibres and plastic fibres. The latter allows steam to escape without explosive spalling.
16
• NOTE: All Six Non Structural Uses can more effectively be accomplished with the lighter pumic aggregates on the Pacific Rim of South America. Thank you [email protected] http://www.unb.ca/civil/bremner/bremner.htm
17
