13 Nov Concrete
Concrete is the most commonly used man-made material on earth; a composite material, consisting mainly of Portland cement, water and aggregate (gravel, sand or rock). It is used extensively in buildings, bridges, roads and dams. Its uses range from structural applications, to pavers, curbs, pipes and drains.
Advantages:
- It is a relatively cheap material and has a relatively long life with few maintenance requirements.
- It is strong in compression.
- Before it hardens it is a very pliable substance that can easily be shaped.
- It is non-combustible.
Limitations:
- Relatively low tensile strength when compared to other building materials.
- Low ductability.
- Low strength-to-weight ratio.
- It is susceptible to cracking
The characteristics of concrete are determined by the aggregate or cement used, or by the method that is used to produce it. The water-to-cement ratio is the determining factor in ordinary structural concrete with a lower water content resulting in a stronger concrete. This, however, reduces the workability (and pumpability) of the concrete, which can be measured using the slump test. The grading, shape, texture and proportion of aggregate can also have a similar affect. If a particularly strong concrete is required, the amount of aggregate can be reduced in relation to the cement. However, cement is a significant cost factor, and increasing its proportion in the mix will increase the overall price.
Below are a couple of links to 3-4min videos of slumps tests:
Stuart-Lynn Company, Inc. provides construction cost estimating, scheduling, and project controls services to a wide variety of clients within the United States and Globally. It is the company’s belief that understanding the financial commitment and planning requirement for a project, provides the control and proactive management to keep projects not only on time and on budget, but to realize the greatest value for every dedicated resource.
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