CONCRETE PRODUCT INFO
Concrete is a mixture of paste and
aggregates (i.e. sand & rock). The paste, composed 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.
while wet or fresh the trait
of concrete is similar to: "plastic" and can be molded or
formed into any shape, colored, and patterned into
beautifully decorative designs, yet, it is strong and
durable when hardened. These qualities explain why one
material, concrete, can build skyscrapers, bridges,
sidewalks, and superhighways, houses and dams.
achieving a strong,
durable concrete rests on the careful proportioning and
mixing of the ingredients. A concrete mixture that does not
have enough paste to fill all the gaps between the rocks
will be difficult to place and will produce rough,
honeycombed surfaces and porous concrete. A mixture with an
excess of cement paste will be easy to place and will
produce a smooth surface; however, the resulting concrete
will be more likely to crack. our suppliers have years of
experience in mixing and transit.
A properly designed concrete
mixture will possess the desired workability for the fresh
concrete and the required durability and strength for the
hardened concrete. Typically, a mix is by volume about 10 to
15% cement, 60 to 75% aggregates and 15 to 20% water, 5 to
8%.air entrainment (air bubbles) for outdoor concrete,
giving more flexibility enduring the elements, indoor mixes
have less air content, creating a denser finished product.
cement's chemistry comes to
life in the presence of water. Cement and water form a paste
that surrounds and binds each particle of sand and stone.
Through a chemical reaction of cement and water called
hydration, the paste hardens and gains strength creating a
long lasting durable paving solution.
The character of concrete is
determined by the quality of the paste. The strength of the
paste, in turn, depends on the ratio of water to cement. The
water-cement ratio is the weight of the mixing water divided
by the weight of the cement. High-quality concrete is
produced by lowering the water-cement ratio as much as
possible without sacrificing the workability of fresh
concrete. Generally, using less water produces a higher
quality concrete provided the concrete is properly placed,
consolidated and cured.
Besides Portland, St. Mary's
and other cement suppliers, concrete may contain other
"cementitious" (cement-like) materials including fly ash (a
waste byproduct from coal burning electric power plants),
slag cement (a byproduct of iron and steel manufacturing),
and silica fume (a waste byproduct from the manufacture of
silicon or ferro-silicon metal). Some of these cementitious
materials are similar to the volcanic ashes the Romans mixed
with lime to obtain their cement binder. Some of these
structures still exist today! The concrete industry uses
these materials, which would normally have to be disposed in
landfill sites, to the advantage of concrete. The materials
help in the hydration reaction and significantly improve the
strength, permeability and durability of concrete.