sand for the foundation has to be clean, and the presence in it of organic matter such as grass, mud or branches unacceptable.In order to clean the sand from foreign matter, it is sieved.It is more difficult to get rid of impurities, such as clay or lime.Even determine their presence in some cases difficult.Clay impurities as used for pouring the foundation sand must be less than 5% of its total weight, if the clay is more, this will reduce the strength of the finished concrete.Checking under construction clean sand, using a transparent container - glass or plastic.
can take an ordinary transparent bottle and fill it one third sand, and then top up with water up to half.Vigorously shaking the bottle, it is necessary to ensure maximum moisture of sand and mixing all the ingredients and then put the bottle
and wait about 5 minutes.If after that time the water in the bottle is dirty, the sand for the construction of the basement is not necessary.Not suitable and the sand in the upper layer portion after shaking with water settles sided material in a thickness greater than 5 mm.
Sand by type can be divided into the river, and marine career.River sand is considered to be a universal subject that he extracted from the bottom of the river.It is used not only for the preparation of concrete solutions, but also for drainage and decoration.Clay impurities river sand has almost no.Sea sand is also extracted from the bottom, then it was purified by shelly debris and impurities.The fraction of the sand is much finer, and therefore it is considered ideal for concrete structures.Career sand on quality can not be compared with the river or sea, but it is much cheaper.
Judging by functionality, the best sand for the foundation to be a river, which is essentially free of fines.Sand by its size is further divided into very thin (less than 0.7 mm) - it is not suitable for the foundation;thin (0.7 to 1 mm) are not recommended for the foundation;very small (up to 1.5 mm) is also better not to use for the foundation.Ideal for the foundation medium (2-2.5 mm) and for high-quality concrete - medium (up to 3 mm).Increased size of sand (to 3.5 mm) is recommended for cushions for the foundation.
builders often advised not to overpay for the foundation and take the cheapest form of sand - a career, because of its use of the quality of the finished building will not be affected.This sand is best to buy on the spot, picked up and washed deselected quarry sand with a grain size of 2-2.5 mm.This sand has sharp edges than enhances binding quality of the concrete.