|
Home / Reference Tools / FAQs
Frequently Asked Questions - Concrete
What is the difference between concrete and
cement?
Most people don’t know the difference between concrete and cement and
if asked they are likely to say something like, "I’ve never really
thought about it but, aren’t they the same thing?" While cement and
concrete are related they are nowhere near the same thing! Cement, which
is the abbreviation of the correct name, "portland cement" is a fine
grey powder that looks very much like gray flour. Most people have never
seen cement. Concrete is a mixture of cement, sand, rock, water and
small amounts of additives. Concrete is the material we encounter in our
everyday lives.
The relationship between cement and concrete is similar to the
relationship between flour and cake. While neither cake nor concrete can
be made without the "flour" they are definitely not flour and like a
cake, when the concrete has finished "cooking" the flour is nowhere to
be seen.
Another way to think about it is that; cement is the glue in the
concrete holding the sand and stone together. It should also be noted
that like many glues, cement doesn’t dry, it hardens through a process
called hydration.
Just as different occasions call for different types of cakes (one
would never take Christmas cake to a 2 year old’s birthday party)
different applications call for different types of concrete. While basic
concrete can be made at home, most concrete today can only be made by
your local ready-mixed concrete manufacturer and delivered ready to use
in a ready mixed-concrete truck.
There are as many different concrete mixes as there are applications
for concrete, and the design mixture used for a parking ramp will differ
radically from the mix used for a basement floor. Furthermore, the
material and procedures used to construct a concrete driveway in a warm
climate, like Southern California, are completely different from the
requirements necessary to construct a durable driveway, pool deck,
walkway or basement floor in a more severe climate, like ours. Freeze
and thaw cycles, coupled with exposure to chemical de-icers can cause
the wrong mix of concrete to crack, shrink or scale.
Mayco makes different kinds of concrete products using different
quantities of aggregates like gravel or crushed stone plus cement,
water, air and sand. Mayco buys most of its aggregate and other raw
materials from local suppliers.
What is fly ash?
Fly ash is a by-product from coal fired electric power generating
plants. The inorganic or mineral constituents of the coal, such as clay,
quartz and shale, fuse and chemically recombine during burning to
produce various crystalline and glassy phases of fly ash. The fly ash is
entrained in the flue gas and cools into spherical, usually hollow
shaped particles. These particles are collected in electrostatic
precipitators or bag houses and the gradation, or fineness, of the fly
ash can be controlled by how and where the particles are collected. Fly
ash reacts with the free lime generated by cement hydration to form
cement-like compounds, which increase the strength and reduce the
permeability of concrete.
Why aren’t highways in Canada made of concrete?
It has been estimated that Canada's national highway network requires
some $22 billion of investment. Furthermore, this number is increasing
because the vicious cycle of maintenance consumes almost all the
available money.
Concrete roads will last up to 40 years with minimal upkeep and will
reduce fuel consumption and accidents. However, despite their obvious
advantages, concrete roads are less common in Canada than in any other
industrialized country, largely because our decision-making has
emphasized the short term. Failure to account for both initial capital
and maintenance costs has placed Canada at a competitive disadvantage
that will need to be redressed in the future.
How do I clean concrete?
Get the details of various cleaning methods depending on the material
you need to clean up. For complete concrete
cleaning tips see the Cleaning Concrete
page. |