Design Examples

Sizing a storeroom with concrete masonry blocks starts with matching the wall plan to the actual block size and mortar joints. The site has concrete masonry units with a nominal size of 8 by 8 by 16 inches. The storeroom is planned with external dimensions of 12 feet long and 8 feet wide.

The wall layout uses nine blocks along the length and six blocks along the width. Each block is actually 7 and 5/8 inches high and wide, and 15 and 5/8 inches long. A 3/8 inch mortar joint is included, so the...

Concrete pavement joints guide where slabs crack and help protect the pavement over time. They support the structural integrity and long life of the concrete by controlling movement and cracking.

Contraction joints, also called control joints, are made by sawing a groove into the concrete soon after it hardens. This groove creates a weakened vertical plane. It encourages cracking at a planned location instead of letting cracks form randomly across the slab.

Isolation joints are used where the...

Well-graded sand is important in concrete because aggregate choice affects strength, mix proportions, and cost. In concrete, sand is the common fine aggregate. When more than one sand source is available, its gradation often guides the selection.

Gradation means the particle-size distribution of the sand. Engineers measure it with sieve analysis, which uses standard sieve sizes from 150 μm to 10 mm, from ASTM No. 100 to the 3/8 in. sieve. This test shows how much sand stays on each sieve and...

Concrete slump testing helps track workability during a raft foundation pour in hot weather. Workability means fresh concrete is easy to place, compact, and finish. In this example, the concrete had to be prepared for a large foundation, so keeping it workable was important for quality and durability.

The first slump test showed low workability. The mix was losing water quickly, and the high temperature made the coarse aggregates hotter as well. To reduce that effect, the site engineer cooled...

Sizing steel bars for a concrete beam helps meet a required reinforcement area. In reinforced concrete design, the steel must be arranged so the beam stays strong and uses material efficiently. This example uses a beam that needs a total steel cross-section of 4 square inches.

The available bars in the example have a nominal diameter of 1.693 inches. Each bar provides a cross-sectional area of 2.25 square inches. When the engineer divides the required area by the area of one bar, the result is...

A sustainable concrete building can use several green design features to save energy, water, and materials. Concrete is a flexible material for these choices, so it supports eco-friendly construction in commercial buildings.

One strategy is to place a concrete parking area under the building. Open areas can use pervious concrete paver blocks, which let rainwater pass through and collect in an underground cistern. That stored water can then be reused for gardening, which improves water...