Plasticizer or liquid soap? What is better for concrete and cheaper for the wallet

Recently, many builders have advised adding liquid soap and other household chemicals to the cement mortar. Is it worth doing and how will it affect the strength characteristics of concrete? Let's figure it out!

What is liquid soap in solution used for?

Builders are not very fond of working with classic concrete mortar due to its low mobility. It spreads poorly, fills cavities and voids of structures poorly.

To increase plasticity in a simple way, two methods were found:

adding more water so that the solution spreads better;
adding detergent.

The first method quickly proved to be ineffective, since water in excess of the established rate reduces the strength and durability of concrete. Excess water in the solution is generally considered a concrete killer.

Liquid soap and washing powders added to concrete give it good plasticity. This method took root, but divided the builders into two camps: some are in favor, others are against concrete on soap. Where is the truth?

How does liquid soap affect concrete?

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Recommended proportion: 200 ml of liquid detergent to 50 kg of cement. Of course, soap increases the plasticity of the concrete solution, makes it softer - it is more convenient to work with such a composition. But do not confuse comfort in work with other characteristics of concrete.

As research from honest bloggers has shown, increased plasticity (immobility) is the only benefit of soap. Household chemicals are not able to give concrete the qualities (strength, frost resistance, hydrophobicity) that a specialized plasticizer gives it.

For example, concrete cubes with a size of 100 * 100 * 100, filled with mortar in a ratio of 1: 4 (cement and sand) with and without soap, have almost the same weight. This means that the shrinkage and air entrainment of the concrete mix are the same.

Tests of these cubes under pressure in the laboratory showed that concrete prepared with a classic solution collapsed at a pressure of 7.6 MPa, and concrete on soap at 7.1 MPa. Both samples were kept for 14 days. At first glance, the difference is insignificant.

What are the risks of using soap in solution?

If concrete from a classical solution serves for years, then concrete on soap collapses much faster. According to some reports, such a stone begins to deteriorate three to five years after pouring.

What is the reason?

The reason is that there is no clear technology for working with detergents in a concrete solution. As a consequence, there is no predictable result. Here, everyone acts on a whim, and the result is different - someone is lucky, while someone's foundation begins to crumble in two years.

Detergents tend to foam. But, foaming does not always occur. For example, if you mix the solution with shovels, this will not happen; and if it is thoroughly "whipped" in a concrete mixer, a reaction will occur and, as a result, the porosity of concrete will significantly increase.

As you know, the more pores in concrete, the faster and more actively it is destroyed. Such concrete is not hydrophobic and absorbs water like a sponge. And what is the threat of moisture in a stone during frost? The answer is banal - freezing and subsequent destruction of the structure.

Homemade plasticizer - how much is it cheaper than a professional one?

Many people think that a factory-made plasticizer is expensive and they use an advanced, homemade one. Samopal consists of PVA glue, slaked lime and washing powder. Moreover, preference is given to washing powder for automatic machines - in the opinion of folk craftsmen, it has less foaming.

Here the proportions and prices are as follows:

lime makes up 20% of the amount of binder - 10 kg per bag of cement - 50 rubles;
for 50 kilograms of cement 200 g of washing powder - approximately 35 rubles;
after all this, 200 grams of PVA is diluted in a bucket of solution - another plus of 7 rubles per bucket.

As a result, you need to spend at least 150 rubles for a bag of cement.

And what prevents you from using the simplest factory plasticizer? Its cost today is approximately 85-150 rubles per kilogram. For a bag of cement, based on the recommended rate of 1% of the amount of binder, you need 0.5 kg, which will average 65 rubles. It is safer, more profitable and faster.

Did you add liquid soap to the solution? Write in the comments what the result is!

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