Sand, Gravel and Stone
Construction Aggregates: How Important are They?
Aggregates have the important role in giving the necessary strength for concrete. Concrete transitions are the interfacial region between the aggregate and cement paste and this is the one that is responsible in giving compressive strength to the cement. Read more great facts on top soil, click here.
The aggregate should be equiangular and round in size and this must not be irregular and flaky. The use of angular aggregates are highly advised because this kind of aggregate comes with a good interlocking effect that gives minimum surface area and will require less mortar to cover the surface.
During the extraction time of the aggregates, care must be taken to make the aggregate go sieve analysis or washing before this will be used. Having the presence of harmful materials like clay, silt or acidic salts will affect the strength and durability of concrete which can lead to inhomogeneity in composition and on the failure of the structure if this will be subjected to eccentric loading. Certain associations specify four grading zones for fine aggregates in order of decreasing particle size that start from coarse sand and ending up with fine sand. You should consider avoiding the use of fine sand in making RCC structures due to the fact that they are porous and can cause corrosions in its reinforcements.
Fine aggregates will include natural sand, crushed natural stone and crushed and these particles must be able to pass through a sieve opening for about 4.75 mm and the ones that are completely retained are coarse aggregates that includes uncrushed gravel and stone and the big boulders.
Aggregates must be inert chemically in nature and has to be tough sufficiently, hard and should possess good bearing capacities.
Aggregates that are well-graded and used in a cement mixture helps to reduce the presence of air voids and also helps in providing sufficient strength and durability to the concrete.
There are actually some tests that are being carried out to some aggregates such as abrasion, impact tests and soundness tests of aggregates which are done by dissolving them to a particular solution of sodium and magnesium sulphate.
In providing support for concrete dams that has a huge mass, aggregates that were formed by igneous rocks has to be used.
Though aggregates are usually commonly known as inert fillers in concrete, the different properties of aggregates gives a large impact on durability, strength, workability and also on the economy of concrete. The various properties of aggregates will allow the designers and contractors the flexibility in meeting their design and construction requirements.Please view this site http://www.ehow.com/how_17326_lay-paving-stones.html for further details.