The seismic retrofit of Barker Hall a six-story 40-year-old concrete building on the University of California Campus in Berkeley required the construction of a concrete belt foundation with bonded post-tensioned -PT- tendons at the top and bottom. The belt foundation supports the new exterior shearwalls and collector beams that strengthen the structure. The shearwalls are heavily reinforced and serve as the exposed facade of the building. A strong committment to green building prompted the structural designer to specify high volume fly ash concrete -HVFA- requiring at least 50% replacement of cement by fly ash. The article contains a description of the materials mixture proportions construction practices and properties of the HVFA concrete used for Barker Hall s foundations and shearwalls. The experience with HVFA concrete at Barker Hall was very positive. Mixture proportion formulation followed by field trial proved to be invaluable in developing HVFA concrete mixtures that met the designer s criteria and expectations and were also accepted by the contractor.

Technical Report Author: P. K. Mehta, Dushyant Manmohan

This paper discusses the use of high levels of fly ash in concrete as part of a “Green Building” at York University in Toronto. In most of the concrete mixes used for the building 50% of the Portland cement was replaced with CSA A23.5 type CI fly ash an industrial by-product from Ontario. Despite the significant reduction in the cement content the concrete produced comfortably met the specified strength requirements was easy to place and finish and its use had no impact on the construction schedule. Such concrete may be suitable for many other commercial or residential construction applications although the material does require some special consideration -e.g. regarding curing- especially when used in a severe exposure condition. This paper discusses the environmental economic and technical issues of using high contents of fly ash in concrete construction.

Technical Report Author: D.S. Hopkins, M.D.A. Thomas, D.B. Oates, Gurinder Girn, Robert Munro

The computer science facility at York University provided Busby and Associates Architects with the opportunity to demonstrate that a “green building” approach is viable in colder climates. Building materials were selected for low embodied energy and reduced construction waste including the specification of high volume fly ash for most of the building s concrete elements. The experience with high volume fly ash concrete in this project was very positive. The original goal of 50% fly ash replacement was reached for the majority of cast-in-place structures and the use of EcoSmart concrete resulted in an attractive finished product excellent workability with no disruption to the construction schedule and no added costs.

Case Study Report Author: Busby Perkins + Will Architects Ltd.