Sustainable Building Technical Manual - Etn-presco.net

(Refer to the “Environmental Impact Questionnaire” in Chapter 17 “Specifications” as anexample of an information-gathering mechanism for a life-cycle assessment of materialoptions. This information can assist the design team in selecting environmentally sensitiveproducts based on the priorities established by the building owner.)☛ SUGGESTED PRACTICES AND CHECKLISTIThe materials discussed below are generic—that is, they are product classes (organized byCSI divisions); several manufacturers may produce products in those classes. This is not acomprehensive listing of all materials for a given use nor an exhaustive list of materials.Resource guides and manufacturers’ product data can provide additional information.(See Chapter 17, “Specifications,” for more information on CSI.)Division 3: ConcreteMaking portland cement for concrete requires substantial energy, causing a significantamount of carbon dioxide emissions. 5 Because concrete is such a high-mass material andis used in buildings in large quantities, considering alternatives is important. If the selectionis based on life-cycle assessment principles, other materials may be preferable.❑ Resource-efficient options– Use fly-ash concrete, available in many regions, as an alternative to conventionalmixes. Fly ash is a waste material from coal-burning power plants. It can be used toreplace up to about 30 percent of the portland cement in conventional mixes. It isalso mixed with ground blast-furnace slag, a waste from metal smelting. Fly ash producesa superior concrete with excellent finishing characteristics; however, onlysome types of ash are appropriate for certain applications, and the proportions arerestricted. Seek technical advice and refer to ASTM standards.– Recycled aggregates and lightweight aggregates are available for some concreteapplications. Recycled aggregate may contain crushed concrete, brick, and othermasonry waste; or it may contain crushed glass. Lightweight concrete is madewith expanded volcanic materials such as pumice and perlite in place of part ofthe usual stone aggregate. These materials place less load on structures (particularlywhen used on wood or lightweight steel floors) and provide some thermal insulationvalue.– Anticorrosion agents such as epoxy coating extend the life of steel reinforcement,especially for applications such as parking slabs where salt is used in winter. Theseagents have been found to extend the life of slabs substantially, avoiding repair andreplacement costs.– Using low-waste formwork is a final step in resource conservation. Systems such asmodular steel forms, slipforms, and preformed blocks can substantially reduce wastematerial from concrete forming.❑ Health and pollution issues– Air pollution emissions from concrete are low. Additionally, concrete is often confinedto foundations and concealed structure where exposure to building air is minimal,although testing on radon emissions is ongoing. Other exceptions are someconcrete additives and some form-release agents, particularly in interiorapplications. 6 Concrete additives such as water reducers or superplasticizers may produceodors and risk of skin and bronchial irritation. Form-release agents are sometimesmade from diesel oil or other odorous petroleum oils that produce emissions.Wax- or mineral oil-based products are available substitutes.Division 4: MasonryMasonry products are made from concrete, clay, glass, and various types of standard andlightweight aggregates. Quarried stone is also used. Most masonry products are installedwith mortar made from portland cement, sand, and lime.