Abstract: The ready-mix concrete producer at times experiences problems with uniformity of his raw materials, and also with secondary properties. Portland cement is no exception. The sources of variations in the properties of portland cement are discussed in this paper as well as the problems that such variations can create; some solutions to these problems are offered. Particular attention is given to the distinction that should be made between the minimum requirements of a general quality specification and the more rigid requirements of a purchase specification. Also noted is the accessibility of test data on secondary properties from the cement manufacturer.
Abstract: Snow drifting is a phenomenon that cannot be avoided in the open areas of most regions of Canada, but troublesome drifts round buildings can be minimized by proper location and shape of building and by suitable landscaping. Special protective measures include fences that collect snow in predetermined places or assist in blowing it away. Careful consideration must be given to the direction of the snow- bearing wind when action is planned to prevent the formation of drifts.
Abstract: A basic requirement of any civil engineering structure is that it does not collapse, causing death, injury or economic loss. It is a requirement that cannot be made absolute. Structures have collapsed, and even with improved technology they will continue to do so. This Digest will consider the risks involved, the main reasons for structural collapse, and how risks are taken into account by structural engineers in design. Finally, as an aid to designers and builders, the Digest will include a list of specially vulnerable situations that have caused most structural collapses in Canada.
Abstract: The prediction of foundation movement is based on knowledge of how foundation loads are transferred to the ground and how the earth and rock materials respond to stress increases. One of the more destructive movements is caused by differential settlements, and their occurrence can often be attributed to local variations in soil compressibility; variation in thickness of compressible soil; differences in footing sizes and pressures; variations in applied load or differences in embedment depth of footings. Three basic types of settlement are uniform, tilt and non-uniform settlement. The "allowable" settlement depends on the type of structure, its size and intended use. Not all movements are unrelated to foundation pressure. The most important are a result of soil shrinkage and swelling. Shrinking is caused by the removal of water, such as "drying out" due to long periods of draught, or removal of water by tree roots. Swelling results from fresh supplies of water not available when the structure was built. Swelling and shrinkage, however, normally occur in fine-grained soil with a large clay content. Other causes of foundation movement may be the result of soil freezing, causing soil heaving, or in the cause of pyritic shales, oxidization which results in volume increase. It is important to remember that all foundations move; the challenge is to predict the behaviour of the foundation and appreciation for the interaction of the soil and the structure.
Subject: settlement; foundations; soil mechanics; swelling clay; shrinkage; Basements and foundations : Foundation movements
Canadian Building Digest; no. CBD-148, ISSN: 0008-3097, Publication date: 1972-04
Abstract: There are daily reminders that every effort should be made to conserve energy, not only because of rising costs but also because of the need to control air pollution. Increased use of insulation to reduce the energy requirements of buildings is one way to achieve these ends. If designers are to design insulation systems and select appropriate materials, however, they should have a clear understanding of how insulation works. This Digest is designeed to provide some of the information required for a better understanding of insulation as a material.
Abstract: Different roofing systems discussed in the opening paragraphs. It must be realized that the performance of a protected membrane system is related to a single membrane that serves as both air vapour barrier and water barrier. It must be continuous and waterproof from installation throughout its service life. It is in a favourable environment in relation to temperature and weather and will usually outlast the insulation, which can largely deteriorate before the membrane will be affected. The life of insulation can be extended by designs that allow for drainage and evaporation of moisture from all sources.
Subject: Roofing; roofs; roofing products; insulating products; water barriers; Air and vapour barriers; Moisture performance; Couvertures : Protected-membrane roofs
Canadian Building Digest; no. CBD-150, ISSN: 0008-3097, Publication date: 1972-06
Abstract:Steeply sloped roofs, low sloped roofs, flooded roofs and roof terraces discussed. A perfectly flat roof cannot be achieved in normal construction and slopes will inevitably develop owing to structural deflections. It is better to build in slopes to control water on a roof. The practicable minimum for main roof areas is about 1/4 inch per foot, and greater slope is desirable. Where drainage is achieved by a folded plate type of arrangement, crickets should be placed at the intersection of the larger slopes to direct water to the drains. When controlled flow drainage or evaporative cooling are required on roofs, a sloping roof produces a less hazardous condition than a flat roof. For protected membrane type roofs, the principal membrane at the deck below insulation and landscaping should be sloped, continuous and sealed round all penetrations.
Subject: Roofing; roofs; drainage; roofing products; water barriers; Moisture performance; Couvertures : Drainage from roofs
Canadian Building Digest; no. CBD-151, ISSN: 0008-3097, Publication date: 1972
Abstract: Pyrite occurrence, volume increase and floor heave, pyrite weathering, factors that enhance pyrite weathering and heaving, design recommendation for basement floor slabs on pyrite bearing rock with known history of heaving, remedial treatment of older buildings are discussed topics.
Abstract: Types of stains appearing on concrete surfaces after building has been in use (spillage of oil, blood, ink, beverages, asphalt or from natural exposures--corrosion, growth of microorganisms, etc,). A summary of types of stains and methods of removal. Detailed procedure for each is discussed.