A40−Slabs-on-Grade

Category Archives: A40−Slabs-on-Grade

Mix Design Fundamentals: Considerations for concrete for slabs-on-ground

Photo © BigStockPhoto/Theerapol Pongkangsananan

Interior concrete should not crack or curl excessively requiring grinding before the flooring can be installed; exterior concrete should not crack or deteriorate prematurely from freeze-thaw cycles. Some argue concrete will always crack, and nothing can be done about it. This is most often an excuse when poor design or poor placement has resulted in excessive cracking or the real problem is too much mix design water, lack of welded wire reinforcement, or too little aggregate and poor curing methods.

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The Value in Standardizing Door Schedules

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by Melany Whalin, CSI
Horror stories abound among hardware consultants who have been called in at the last minute to create hardware specifications that were needed yesterday, only to be given incomplete or inaccurate door schedules on which to base their specifications.

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Better Concrete Starting at the Finish: Long-term benefits of colloidal silica-based finishing

Images courtesy Lythic Solutions

Recently, concrete contractors have started using a colloidal silica-based compound as a finishing (or ‘troweling’) aid for flatwork. It makes the surface denser, and increases the quality of cement paste. Additives in the compound help the surface slow evaporation though hydrophobic properties, protecting the concrete from a range of moisture loss-related defects. It also makes it unnecessary for contractors to add water to finish the concrete. The result has implications for buildings, pavements, roadways, bridges, and even precast structural and architectural concrete.

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Out of Sight, Not Out of Mind: Specifying thermal insulation below-grade and under-slab

All photos courtesy Insulfoam

Balancing performance and cost for insulation installed on below-grade foundation walls and under floor slabs can require specifiers to rethink common assumptions about rigid foam insulation. Misperceptions about the moisture absorption of expanded polystyrene (EPS) compared to extruded polystyrene (XPS) may be limiting more cost-effective choices. Test results demonstrate the long-term durability and moisture resistance of EPS insulation and the stability of its thermal performance. In many applications, substituting a strong and adequate, yet lower compressive resistance insulation, can result in significant cost savings.

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