The evolving uses of concrete
Concrete is like putty in the hands of an architect or engineer. It’s easy to manipulate. It can take any shape, turn any colour, mimic any texture, span great distances and weather any storm. This interesting description by the Cement Association of Canada really reinforces the versatility and unique characteristics of concrete. This month we take a look at some stunning ways that concrete has been used in Canada recently. Andrew Vizer describes the use of jet-grouting for the Olympic Village project in Vancouver (page 12).
One of the largest continuous mass pour raft foundations in the world was completed last year in Calgary for Phase I of Centennial Place East Tower, a 1.2 million square foot (111,484 square metre) office development (page 11).
Preparing these articles, I was interested to read about other types of concrete and their applications. Here are a few from the Cement Association of Canada.
Aerated Autoclave Concrete (AAC), more commonly known as “cellular concrete,” dates back to 1923 with its origins in Stockholm, Sweden. It is a tough, resilient, lightweight construction material which is easily handled, cut, shaped or molded to virtually any profile. It can be saw cut, drilled, screwed and nailed, similar to wood. It will maintain its high strength, excellent durability, thermal insulation, sound insulation and fire resistance. Cellular concrete has undergone many improvements over the years and one of its benefits is its light weight. Previously the universal potential of lightweight concrete was impeded by the significant capital cost of the manufacturing system that employed an autoclave (steam pressure) process. Insulating Concrete Forms (ICF) are polystyrene forms that stack like blocks. Once these blocks are assembled, concrete is poured into the hollow core of the block to create walls. They are either shaped into pre-formed interlocking blocks or separate panels connected with plastic ties. These left-in-place forms not only provide continuous insulation on both sides of the wall, but also provide a backing for drywall on the inside and stucco, lap siding or brick on the outside. High-Performance Concrete (HPC) exceeds the properties and construc-tability of normal concrete. Normal and special materials are used to make these specially designed concretes that must meet a combination of performance requirements. Special mixing, placing, and curing practices are needed to produce and handle high-performance concrete. HPC is used in tunnels, bridges, and tall buildings for its strength durability, and high modulus of elasticity. It has also been used in shotcrete repair, poles, parking garages, and agricultural applications. Reactive-Powder Concrete (RPC) is characterized by high strength and very low porosity, which is obtained by optimized particle packing and low water content. The properties of RPC are achieved by: (1) eliminating the coarse aggregates; just very fine powders are used such as sand, crushed quartz, and silica fume, all with particle sizes between 0.02 and 300 micrometres; (2) optimizing the grain size distribution to densify the mixture; (3) post-set heat-treatement to improve the microstructure; (4) addition of steel and synthetic fibres (about 2 percent by volume); and (5) use of superplasticizers to decrease the water to cement ratio – usually to less than 0.2 – while improving the rheology of the paste. Solidification/Stabilization (S/S) treatment is used to treat hazardous wastes for disposal, and in the remediation/site restoration of contaminated land. S/S is a popular technology in brownfield (industrial property) redevelopment since treated wastes can often be left on-site to actually improve the site’s soil for subsequent construction.
One of the largest continuous mass pour raft foundations in the world was completed last year in Calgary for Phase I of Centennial Place East Tower, a 1.2 million square foot (111,484 square metre) office development (page 11).
Preparing these articles, I was interested to read about other types of concrete and their applications. Here are a few from the Cement Association of Canada.
Aerated Autoclave Concrete (AAC), more commonly known as “cellular concrete,” dates back to 1923 with its origins in Stockholm, Sweden. It is a tough, resilient, lightweight construction material which is easily handled, cut, shaped or molded to virtually any profile. It can be saw cut, drilled, screwed and nailed, similar to wood. It will maintain its high strength, excellent durability, thermal insulation, sound insulation and fire resistance. Cellular concrete has undergone many improvements over the years and one of its benefits is its light weight. Previously the universal potential of lightweight concrete was impeded by the significant capital cost of the manufacturing system that employed an autoclave (steam pressure) process. Insulating Concrete Forms (ICF) are polystyrene forms that stack like blocks. Once these blocks are assembled, concrete is poured into the hollow core of the block to create walls. They are either shaped into pre-formed interlocking blocks or separate panels connected with plastic ties. These left-in-place forms not only provide continuous insulation on both sides of the wall, but also provide a backing for drywall on the inside and stucco, lap siding or brick on the outside. High-Performance Concrete (HPC) exceeds the properties and construc-tability of normal concrete. Normal and special materials are used to make these specially designed concretes that must meet a combination of performance requirements. Special mixing, placing, and curing practices are needed to produce and handle high-performance concrete. HPC is used in tunnels, bridges, and tall buildings for its strength durability, and high modulus of elasticity. It has also been used in shotcrete repair, poles, parking garages, and agricultural applications. Reactive-Powder Concrete (RPC) is characterized by high strength and very low porosity, which is obtained by optimized particle packing and low water content. The properties of RPC are achieved by: (1) eliminating the coarse aggregates; just very fine powders are used such as sand, crushed quartz, and silica fume, all with particle sizes between 0.02 and 300 micrometres; (2) optimizing the grain size distribution to densify the mixture; (3) post-set heat-treatement to improve the microstructure; (4) addition of steel and synthetic fibres (about 2 percent by volume); and (5) use of superplasticizers to decrease the water to cement ratio – usually to less than 0.2 – while improving the rheology of the paste. Solidification/Stabilization (S/S) treatment is used to treat hazardous wastes for disposal, and in the remediation/site restoration of contaminated land. S/S is a popular technology in brownfield (industrial property) redevelopment since treated wastes can often be left on-site to actually improve the site’s soil for subsequent construction.
