Not any sand is suitable for plaster, and for construction sandy raw materials there are even standard rules. You do not hurry, beginners to take the first sand as "stuffing" for plaster solution. We advise to learn about what sand as different types of sand is affect characteristics of solution of plaster and the end result of finishing works.
We choose sand for plaster of a necessary type
Sand to sand – discord, as by origin, and on properties. When it understood, there is a question of what properties of sandy filler of plaster solution and what sand needs to be taken for plaster influence. Sand raw materials are formed in the course of an erosion of rocks and represent mix of grains of various form and the size (from dust to small stones up to 5 mm in size).
As a part of construction solutions sandy grains carry out a role of the melkorazmerny framework providing durability of solution of plaster and its reduction in cost. Grains of sand, remaining chemically inert, are fastened with each other with the kristallika of the knitting substances formed during chemical reaction. Durability of these communications, therefore, – all artificial stone (the hardened solution) depends on roughness and a form of grains. (As a part of solution) depends on the volume of sandy filler, it is how more or it will be required a binding component less.
At first we will note that sandy material is natural and artificial.
Deposits of natural sand happen by origin:
sea;
career (or ovrazhny);
river.
From by what way these deposits were formed, such characteristic as a form of sandy grains and content of foreign inclusions depends. Foreign inclusions can be not so inert as grains of sand.
mica impurity
For example, as undesirable impurity are considered:
organic matter (reacting with cement, destroy it);
connections are gray (participating in reactions, become the reason of corrosion of metal and decomposition of cement);
parts of mica (are fragile, easily disappear, are badly linked to a solution basis);
dust-like and oozy particles, clay educations (having the sizes less than 0.15 mm, envelop grains of sand and interfere with coupling of crystals with them binding).
State standard specification normalizes the top limit of maintenance of these particles and ways of determination of their quantity in sandy raw materials.
If the maintenance of organic chemistry and sulfur can be revealed by laboratory methods, then availability of silt and clay is defined, having rubbed a handful of wet sand in palms. Pure sand grains do not soil a palm.
Important characteristic – particle size distribution – a percentage share of grains of various size.
By the size of grains divide sand raw materials into fractions:
large (grains from 2 to 4 mm);
averages (sizes of parts from 0.5 to 2 mm);
small (particles within 0:25 up to 0.5 mm).
For decorative structures sandy material can be also very small fraction (up to 0:25 mm).
The shade depends on of what breeds sand raw materials were formed.
Color of a loose product can demonstrate also presence of some minerals:
reddish and orange shades are inherent in oxides of metals;
shades of a greenish or bluish outflow – to river sands with aluminum salts;
quartz grains are distinguished by white color.
Quartz sand – quite rare material therefore is more expensive. Apply to primers, for example, of the betonkontakt, some types of plasters.
What gives use of river sand for plaster
To answer a question, it is necessary to deal with features of river filler. Before to settle in the bed of the river, a grain of sand and larger stone fragments formed at aeration of a stone make a long way. At inclination water streams grains are rolled and become roundish. This feature of a form of grains affects (plasticity) of placeability of plaster mix, roundish grains of sand do not cling the friend to the friend sharp ledges.
extraction of river sand
The second feature, which reason – rounded shape, – shrink resistance of plaster mix. When putting solution roundish grains keep within densely at once and, forming a skeleton, practically do not allow a plaster covering to sit when drying and curing. Solutions with river filler are nonshrinking (shrinkage size very small) therefore thickness of a newly-laid layer and hardened is identical.
This property is welcomed for production of concrete couplers, the bases, mixing of masonry solutions.
The shrink resistance back – increase in volume of the necessary knitting substance. Intervals between grains of rounded shape it is more, than between grains of angular forms and to reduce them an utrambovyvaniye or vibrating it will not turn out.
River sand most often has larger granules, than career.
The smaller maintenance of particles clay or oozy – the advantage of raw materials of this type. Except the need for bigger quantity knitting, minus is that the cost of such sand for plaster of walls is higher (because of technological features of production, for example, of use of a hydroalluvium). Plaster solution with river filler sticks to the unprepared bases worse.
River filler is applied in decorative structures, for example, to plaster a bark beetle. It is more preferable to a nakryvka layer (and in general than the top plaster layers). The small fraction of a river sand can be used for independent preparation of hard putty (involving it with acrylic aqueous emulsion ink or glue).
Use of sand from a pit
Ovrazhny sand usually more small. Career material has angular grains that gives to solution property of shrinkage. At vibration of a granule can be displaced, then smaller move in intervals between large. The similar picture arises in the course of a skhvatyvaniye when the appearing crystal communications pull together the next particles of filler with themselves. On 1 cm of height of a layer shrinkage can be 1 mm.
Such behavior of solution is admissible for a nabryzg and soil at draft alignment. But if at alignment on beacons on one site of a wall the layer of 5-6 mm, and on another – 3 cm is imposed, then after solution hardening the surface will not be equal.
Or for finishing of utility rooms career sand for plaster is more preferable to processing of facades.
Ovrazhny material is cheaper, more often meets, extracted with smaller expenses. It contains more clay particles, may contain mica and connections are gray. Therefore it is better to buy such filler from the reliable producer.
In the made plaster mixture of a grain of sand of ovrazhny origin settle quicker, than roundish river therefore solution with career sandy filler is recommended to a thicket to be mixed for maintenance of uniformity of weight.
If the quality of career raw materials is unknown, the portion of material is filled in with water with addition of alkali (small amount). If sandy weight darkens, it is washed out at least three times. It is also obligatory to sift to remove large and foreign inclusions.
Sometimes it is possible to level features of career filler additive to it river.
Sea sand
Sea sand belongs to natural, is extracted in Russia in the Gulf of Finland and the Crimea. The sand material lying at the bottom is polluted by various organic and also inorganic impurity (clay) therefore it is subjected to clarification. Due to expensive purification and rather small amount of the material coming to the market, this sand is more expensive than other types. It has the best qualities in comparison with river, its application allows to lower a cement consumption therefore sea sand is used willingly by producers in compositions of decorative plasters.
extraction of sea sand
Special types of sand for plasters
Except natural in construction use artificial sand filler. It is received from waste from crushing of stone breeds. The stone is ground, the formed material is washed out and fraktsut, receiving angular grains at the exit. Such filler can give big shrinkage.
Artificial grain material is processed sometimes powder dry glues for increase in adhesion. For the increase in surface area and roughness necessary for plaster structures, grains subject to thermal training. All this affects cost.
Beginners need to know: what use of sand is better for plaster of walls?
Plaster structures differ from concrete because plaster material has to satisfy the following conditions at the same time:
the plaster layer has to be vapor-permeable for what in it there have to be air time;
solution has to create a covering of sufficient durability and at the same time have the minimum shrinkage;
the structure has to be both plastic and viscous (that did not flow down from walls when laying) at the same time.
These qualities are regulated during a batch by addition of the modifying additives, lime and sand. Correct will use the most suitable option of sandy raw materials for each of plaster layers.
For example, for:
layers of a nabryzg and soil it is better to use the raw materials extracted in career;
decorative structures, a nakryvka or the top layer of earth (at plaster of walls without nakryvka) – river filler.
Cement mortar
Knitting cement is the most popular. In cement plasters usually use cheaper filler, however, use of both river, and career material is allowed.
cement and sand solution
Ovrazhny filler is required to be purified previously:
to sift through a grid with a cell 4-5 mm, having removed beforehand large garbage;
to wet and to stir periodically that clay lumps dispersed (on 4-5 hours);
to merge the polluted water, having replaced with clean;
it is vigorous to stir weight and to merge the top part of contents of capacity in the second capacity;
after upholding to merge water, to dry sand.
Limy mix
Lime, breaking up when clearing, forms the smallest particles thanks to what limy solution has high plasticity. Therefore even the angular career sand well keeps within when putting limy solution. Most often it is used for fat lime. For the lean limy test as filler serves river material.
Clay solution
As filler for clay plaster use both types of sandy material. If clay lean, then the batch is carried out on dirty river raw materials. Apply career filler to the fat clays having high plasticity. Proportions select mixing of samples.
clay solution
As it is correct to sift sand
Use metal wattled gauzes with a cell to 5 mm to sifting of a large amount of sand raw materials (usually for cement mortars use filler with granules of 2-4 mm). The grid can be fixed on a wooden frame with sides. If the volume of sandy mix small, then it is possible to pull either a mosquito grid, or tulle. For sifting take dry material.
separation from sand of large impurity
If sandy raw materials are polluted by clay inclusions, it before sifting is washed out and dried up.
Usually are engaged in sifting on the street. It is necessary to choose dry not really windy day. Air flow will blow easy dust particles of dirty material, and will place small grains of sand away from large alee.
For sifting of sand there are also special installations, but you should not get them for single works.
GOST standards
The main characteristics which sand for plaster has to have are stated in two standards – GOST 8736-2014 and GOST 28013-98. According to them, granular filler is divided into two classes:
The I class – coarse-grained sandy materials;
The II class – the fine-grained fillers which in addition have smaller fractions, for example, very thin (with grains less than 0.16 mm).
For each class the maximum allowed content of harmful impurity or components, dust-like particles is registered.
Composition of plaster
Any plaster solution includes several components. On their appointment components divide into binding (forming the knitting basis), the fillers (which are not entering chemical reaction inert substances), modifying additives.
The knitting substance
Among the knitting materials cements are spread more. For the plaster purposes usually use a portlandtsement (can apply other cements to special plasters). For interiors as binding substance use plaster, is more rare – lime, sometimes – clay. These are classical mineral knitting which can be used as alone, and in a complex, for example, cement and limy structures. From modern materials for a basis use polymers.
Binding depend on a look:
durability of a plaster covering;
adhesion (tenacity);
durability;
skhvatyvaniye time;
water resistance;
plasticity (for example, additive of lime increases placeability), etc. characteristics.
Filler
Reduction of amount of more expensive binding substance was the main destination of filler long since. For the plaster purposes as the main filler long since serves sand. Its quantity in solution is defined in parts from quantity (volume or weight) of the basic knitting. Except sandy filler, slag, artificial granules and fibers of various origin can be a part of plasters.
The quality of a plaster covering also depends on quality of filler. Therefore to a look and quality of sand special demands are made.
We recommend also useful video on article subject.
For plaster works it is possible to use any of sands. But each of types of sandy material has features which need to be considered. Having correctly chosen the necessary sand for plaster, according to its features, you will avoid surprises in work and receive a plaster covering of high quality.
mica impurity 
extraction of river sand 
perlitovy sand 
clay solution 
