How to make strong and durable concrete at home: good advice

Filling the path, platform, blind area, and indeed any concrete structure, we want it to serve for a long time. But concrete has an insidious enemy - water. We will tell you with what additives to improve concrete and minimize the destructive effect of moisture.

There will be no old-fashioned ways and miraculous recipes like adding chicken eggs or washing powder to the solution. Now is a different time and problems are solved by different methods.

From personal experience

The user of our portal Andrey shared an interesting experience.

“From 2006 to 2014, I produced a number of concrete products: wall and partition blocks, foundation blocks, paving slabs. There is knowledge about this material.

I am a supporter of construction chemistry, I have always used various additives and know the effect of their use well.

In 2007, I came across an American-made waterproofing. It is a liquid that penetrates deep into concrete and provokes the formation of crystals in voids. Crystals fill and clog pores, capillaries and cracks. This provides the concrete with a waterproofing effect.

After translating the instructions, I learned that this liquid can be added to the cement mortar to improve the waterproofing properties of concrete. But the proportions were not indicated there.

In the standard composition for the manufacture of a hollow block, I added this waterproofing at the rate of 3% by weight of cement. This recipe also included a plasticizer - 1%. The result was a solution that began to harden unusually quickly.

I limited myself to one batch - I made 4 blocks. The products turned out to be strange, with some atypical glass sheen. The very next day, these blocks gained record strength - they did not break when dropped on the concrete floor.

A couple of days later, I was once again convinced of the quality: I threw a block of meters three meters above the concrete floor - not a crack. Then one slammed against the rail. And only after a strong impact on the piece of iron the corner broke off. But it did not crack and retained its shape.

After a week, I gave a couple of blocks for research. In the laboratory, the product cracked when the press delivered a load of over 150 kg / cm2. And this is a hollow block! "What did you put in it?" An employee of a construction agency asked in surprise.

After that, I worked out the recipe and launched this unit into small-scale production. They did not buy it for large objects - it was expensive, but they took it well for baths, cellars and wet rooms.

That's how I discovered the recipe for strong, durable, waterproofing concrete. "

Capillaries and cavities - the cause of concrete destruction

How does water get into concrete? Answer: through the capillaries. After hardening, pores and cavities remain in the material. Capillary pores are formed by evaporation of moisture that was between the grains of the aggregates.

Cavities are formed due to the low mobility of the mixture. That is, the mixture did not thicken, there was air in it, which forms various voids. This happens when the mixture is not compacted by the vibrator.

The destruction process begins from water in concrete. It accumulates in the voids; at low temperatures it turns into ice, which breaks the structure of the material. And even without water, porosity steals strength: if the amount of air in concrete is 6%, the brand falls by half.

How to minimize pores and voids: additives

To obtain high-quality concrete, you need to use two additives:

• plasticizer - 1% by weight of cement;
• penetrating capillary waterproofing - also 1% by weight of cement.

But for different manufacturers of penetrating waterproofing, dosages may differ and reach up to 5% of the mass of cement. Read the instructions carefully! Most plasticizers are used at a rate of 1%.

The plasticizer will make the mixture mobile and compact it. This will eliminate voids and minimize porosity. Penetrating (penetrating) waterproofing will fill the capillaries with water-insoluble crystals, which will give a high waterproofing effect.

How much water to add to the solution

High quality additives alone cannot be achieved. You need to correctly calculate the amount of water.

The mixing water is calculated using a special coefficient - 0.4. The proportions in this calculation are not of particular importance - the calculations are carried out on the basis of the mass of cement.

Example: for 1 bag of cement (50 kg) add 500 grams of plasticizer (this is 1%) and 500 grams of penetrating waterproofing (also 1%). Water for this amount of cement is added by a coefficient of 0.35. This means the weight of cement in kilograms is multiplied by 0.35. Calculation: 50 * 0.35 = 17.5 liters.

The plasticizer must be diluted in water in advance (500 grams per 1 liter of warm water). If it is dry, add penetrating waterproofing immediately to the mortar. If it is liquid, add along with the plasticizer.

How to do it:

• pour cement and aggregates - sand, crushed stone into the concrete mixer;
• stir dry;
• add waterproofing (powder) and stir again to dry;
• pour in the mixing water and stir for 3-5 minutes;
• add plasticizer and turn on the concrete mixer for another 7-10 minutes.

If the waterproofing is liquid, then it must be introduced with mixing water or with a plasticizer.

The solution is ready, you can use it! With this approach, you get strong, durable concrete. The plasticizer, in addition to all its qualities, also increases the strength of the material.

It will come out a little more expensive than standard concrete, but it will last much longer.

How do you make concrete? Write in the comments!

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