Regular concrete

TEXT 2. TYPES OF CONCRETE

J. The most common types of admixtures are accelerators, retarders, air-entrainers, plasticisers, pigments, corrosion inhibitors, bonding agents.

I. Chemical admixtures give concrete certain characteristics not obtainable with plain concrete mixes.

H. The water and cement paste hardens and develops strength over time.

D. Recycled aggregates are used as partial replacements of natural aggregates.

1. Concrete solidifies and hardens after mixing and placement due to a chemical process known as hydration.
2. It is used to make pavements, architectural structures, foundations, motorways/roads, parking structures, brick/block walls and footings for gates, fences and poles.
3. Concrete is used more than any other man-made material on the planet.

1. Without accelerants, concrete may take centuries to cure.
2. Entrained air is a trade-off with strength, as each 1% of air may result in 5% decrease in compressive strength
3. Cement requires time to fully hydrate before it acquires strength and hardness.
4. Curing is the process of keeping concrete under a specific environmental condition until hydration is relatively complete.
5. A moist environment promotes hydration
6. Excessively high temperature can result in tensile stresses and cause the concrete to crack.
7. Exothermic chemical process of hydration can be problematic for very large placements.
8. Interrupted hydration process due to freezing can reduce the concrete strength and leading to scaling and other damage or failure.

Ex.13. Write down the key sentences from the text:

1.

2.

3. …

Ex. 14. Summerise the text. Use the key sentences from the previous exercise as a plan for your rendering.

For more specific information concerning building brick buildings read text 2 ‘TYPES OF CONCRETE’ and get ready to answer the questions following the text and the list of vocabulary.

Various types of concrete have been developed for specialist application and have become known by these names.

Regular concrete is the lay term describing concrete that is produced by following the mixing instructions that are commonly published on packets of cement, typically using sand or other common material as the aggregate, and often mixed in improvised containers. This concrete can be produced to yield a varying strength from about 10 MPa to about 40 MPa, depending on the purpose, ranging from blinding to structural concrete respectively. Many types of pre-mixed concrete are available which include powdered cement mixed with an aggregate, needing only water.

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