Skinny concrete: what is it; where applicable; how to do

Skinny concrete is a name that raises many questions for those who are not associated with construction. It is often possible to hear from self-builders that this is inferior, cheaper concrete with reduced strength characteristics, which is used somewhere on large construction sites. Let's figure out where skinny concrete is used and how to make it at home.

What is skinny concrete

Skinny concrete is a solution where the amount of cement and water is reduced, and the volume of fillers: sand and cement is increased. Its counterweight is oily concrete, where, accordingly, the amount of cement is large. GOST 26633-91 regulates the consumption of binder in lean concrete mixtures. Proportions for making one cubic meter of mixture:

• cement (M300) - 0.18-0.2 tons;
• fine crushed stone (5–40 mm) - 1.3 tons;
• sand - 0.9 tons;
• water - no more than 70 liters;
• plasticizer - no more than 5% by weight of cement.

Lean concrete characteristics:

• specific weight - 2500 kg / 3;
• frost resistance - from 50 to 100 cycles;
• compressive strength - from 80 to 190 MPa;
• water resistance - 6%;
• mobility - 10-15 cm.

Water plays a key role in this type of concrete. It is known: the more water in the solution, the less the concrete strength at the outlet - this applies to any type of concrete. The decrease in the amount of binder is partially compensated for by the low water-in-solution ratio. But with such a small amount of water, the mobility of the mixture is given by plasticizers.

If you increase the amount of water, this will entail increased shrinkage of the solution, as well as a decrease in: strength; frost resistance; crack resistance of the finished structure. The solution water should not contain: surfactants; salt; fats; petroleum products - then you shouldn't blame the technology if you add water to the solution in an oil barrel!

Where is skinny concrete used?

There are many applications for this concrete, as it brings significant savings in construction. In industrial volumes, it is used on construction sites, in road construction, in the construction of runways. In private housing construction, these are screeds, paths, footings, numerous bases for the foundation, preparatory layers for pools.

How to prepare skinny concrete on a construction site

Although this building material is cheap at the exit, it is problematic to prepare it manually - you need a concrete mixer. Manufacturing technology is very simple. First, a filler is poured into the mixer: cement, sand, crushed stone. All this is mixed dry until a homogeneous mixture. At this time, the mixing water is prepared: a plasticizer is added to the water and stirred.

To work at home, the volume of water can be calculated as follows: the amount of cement in kilograms must be multiplied by a factor of 0.4. For example, a 50 kg bag of cement goes into the solution. Multiply 50 * 0.4 = 20 liters of water.

When the mixture is mixed to dry, mixing water is added and all this is stirred until smooth. The finished solution will resemble a semi-dry mixture that crumbles in your hands. When placing lean concrete, a vibrating tool or roller must be used.

What proportions do you use to prepare concrete? Write in the comments!

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