We’ve put together these questions and answers to share 100 years of concrete knowledge with you.
What is concrete?
In its simplest form, concrete is a mixture of paste and aggregates (sand & rock). The paste, a combination of cement and water, coats the surface of the fine (sand) and coarse aggregates (rocks) and binds them together into a rock-like mass known as concrete.
Isn’t cement and concrete the same thing?
Contrary to popular belief, concrete and cement are not the same thing. Just like flour in a cake mix, cement is an “ingredient” in concrete. Cement acts as the binding agent when mixed with water and aggregates form concrete.
Why does concrete crack?
The majority of concrete cracks usually occur due to improper design and construction practices, such as:
a. Omission of isolation and contraction joints and improper jointing practices.
b. Improper sub-grade preparation.
c. The use of high slump concrete or excessive addition of water on the job.
d. Improper finishing.
e. Inadequate or no curing.
What special attention needs to be paid when pouring concrete in hot weather?
High temperatures cause increased water demand which, in turn, will raise the water-cement ratio and result in lower potential strength. Higher temperatures cause a rapid rate of evaporation of moisture from the surface of the concrete and accelerated setting time.
What special attention needs to be paid when pouring concrete in cold weather?
Low concrete temperature has a major effect on the rate of cement hydration, which results in slower setting and rate of strength gain.