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Ready Mix Concrete is a mixture of sand, stone, cement and water. Stated in other terms, concrete is a composite of paste and aggregate combined to form a solid material. The paste is comprised of cement (a powder) and water. There may also be other ingredients added such as flyash, ground granulated blast furnace slag, silica fume and a variety of admixtures to affect the properties of Ready Mix Concrete. The aggregates are fine aggregate (sand) and coarse aggregate (stone). The sand and stone act as fillers in the Ready Mix Concrete. The sand fills the voids between the larger stone pieces. Many people, even professionals, often confuse concrete with cement. Cement is the powder used to make concrete. The kinds of cement and concrete used today are similar to those used by the ancient Romans. After the Roman Empire fell in the fifth century, people lost the art of making cement and it was not rediscovered until the mid- 1700's. Cement, from Latin caementum, "rough-cut stone,"is made by heating crushed limestone and clay for shale in a huge kiln. This forms a clinker that when ground into a powder, becomes cement. It is mixed with water and materials such as sand, gravel, and broken stone to make concrete. Cement and water form a paste that binds the other materials together as the concrete hardens, a process reflected in the etymology of the term itself. Concrete is a combination of the Latin prefix com-, "together," and crescere, "to grow." Cement has to be kept dry in enclosed vessels and can be stored for years. Cement is delivered to our plants in aluminum bulk trailers. Gradation in the aggregates is important for a well-consolidated, strong mix. Fine aggregate consists of particles with a top size of 3/8 of an inch. Coarse aggregates are any particles greater than 0.19 inch, but generally range between 3/8 and 3/4 of an inch. A typical mix is made up, by volume, of 10 to 15% cement, 14 to 18% water, 4 to 8% entrained air, 24 to 28% sand, and 31 to 51% stone.
The cement-water combination is the paste that binds everything together and becomes the foundation of concrete's strength. The ratio of water to cement is called the water cement ratio. The lower the water cement ratio is, the stronger the Ready Mix Concrete is. We can design Ready Mix Concrete that will be so weak that you can dig it out after it has hardened. This is a desirable trait for backfilling around pipes that may have to be moved later. We can also design Ready Mix Concrete with strengths exceeding 10,000psi (pounds per square inch) which is normally used in high rises and special applications. Most Ready Mix Concrete used in residential work is 3,000psi - 6,000psi. Our dispatchers can help you select the right mix for your job. The number of different mixes and variations on mixes is endless. Some commonly used mixes are: 3000psi 4000psi 5000psi While a 3000psi mix is equated with having a 28 day strength of 3000psi, one must be careful. A 3000psi mix that has had too much water added bringing it up to an 8" slump would probably not reach 3000psi. A 3000psi mix that is placed and left unprotected in 35 degree temperatures would have a tough time obtaining 3000psi in 28 days. This is where ordering by "specified strength" or asking for a "performance mix" can be an advantage. You may want a final minimum strength of 4000psi in 28 days, but need 3000psi in 4 days and have to place the concrete at a 9" slump in 40-degree weather. You tell us what you want in the way of strength and slump and the condition in which you will be placing concrete and our quality control department can design a mix that can meet your needs.
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Ready Mixed Concrete | Do-it-yourselfer | Professional Contractors | Showcase | About TNT Materials CONCRETE DISPATCH (530) 582-3600 TNT Materials
- Marsh Ventures, Inc. |
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