by Louis Yannotti,
Concrete expert at Premiere Concrete, Los Angeles
What is Concrete? What is Cement?
People mix up (no pun intended) the terms concrete and cement. Cement is an ingredient of concrete (Cement comprises 10 to 15% of a concrete mix). Concrete is a mixture of sand and gravel or crushed stone and paste. The paste is water and cement. That cement is technically termed, “Portland” cement. Portland cement is not a brand name or a reference to the city. It’s a generic term for the type of cement used in just about all concrete mixtures. Through a process called hydration, the cement and water harden to bind all the concrete aggregates into a rock like mass.This hardening continues for years-concrete gets stronger as it gets older.
What is Ready Mix?
Ready mix, is the concrete that can be seen delivered to job sites via cement mixers.The big, round-ish vessel on the back of those trucks rolls and hence; mixes the concrete (the hydration process) during delivery for on the spot pouring.
What is “Finishing”?
“Finishing” is how the surface texture of a concrete job
is crafted. There are various steps in this process including:striking-off, floating, jointing, troweling-texturing, edging and curing.
Can you pour concrete during a rain?
Yes. You can work with concrete during a rain by protecting it from getting too much water. Plastic tarps do the job. The surrounding area should also be protected from getting too much water.
Can it be too cold to pour concrete?
It can: Concrete does not harden in temperatures below 35 degrees (Fahrenheit). To work in lower temps, we can warm the water and add accelerating additives, etc. Working in these conditions simply adds expense. In the Los Angeles area, with so little freezing, this only becomes a factor “once upon a blue moon.”
Can it be too hot to for concrete construction?
Temperatures above 90 degrees Fahrenheit cause concrete to “cure” or harden faster. They can also affect how strong the concrete becomes. Wind and humidity (how much moisture there is in the air) can also effect the concrete hydration process. These factors should be considered when scheduling pours, deciding upon additives and finishing.
Is concrete environmentally sound product?
Yes. Concrete is an environmentally inert compound. It does not include petro-chemical products or elements that may effect water supply.