Footings, slabs, forms, curing, grading and site safety.
40 cards · basic cards · AI-written, checked twice. Edit anything.
- What is the minimum depth a footing must be placed below grade to avoid frost heave?
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Below the frost line for the region, typically 3 to 4 feet in northern climates- Define bearing capacity of soil.
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The maximum load per unit area that soil can safely support without excessive settlement- What is a spread footing?
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A shallow footing that distributes a column load over a wide area of soil- When is a pile foundation used instead of a spread footing?
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When soil has poor bearing capacity, is very deep, or when the structure needs support at great depth- What is frost heave?
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Upward movement of soil and structures caused by ice lens formation in frozen ground- What determines the size of a spread footing?
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The column load, bearing capacity of the soil, and depth of the footing- What is the difference between a mat foundation and a spread footing?
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A mat foundation supports multiple columns or an entire structure; a spread footing supports a single column- Why is rebar placed in footings?
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To resist tensile stresses and prevent cracking from bending and shear forces- What is a concrete slab-on-grade?
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A concrete slab poured directly on the ground, commonly used for floors in buildings- What is a control joint in concrete?
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A planned weak point cut into concrete to direct and control where cracking occurs as the concrete shrinks- Why is a vapor barrier installed under a slab?
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To prevent moisture from wicking up through the concrete from the soil below- What is the typical thickness of a residential concrete floor slab?
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4 inches- What is welded wire fabric used for in slabs?
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To provide temperature and shrinkage reinforcement to control cracking- What is a thickened-edge slab?
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A slab-on-grade where the perimeter is thickened to provide additional support and frost protection- Why are joints placed in concrete slabs?
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To control crack location, relieve stresses from temperature changes and shrinkage, and allow for movement
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