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

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.

TEXT 2. TYPES OF CONCRETE

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