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 Technical Information -- Frequently Asked Questions
 
 
 
1. Does DPS repel Acids?
Answer

The types of acids used were: -
- Phosphoric acid
- Citric acid
- Oxalic acid
- Sulphonic acid
- Hydrochloric acid
- Sulphuric acid
- Hydrofluoric acid
- Caustic soda
- Caustic potash

As you know, Hydrofluoric Acid (HF) is one of the strongest and most corrosive acids known with a pH value of about 1.00. Therefore, special safety precautions are necessary when using this chemical. Hydrofluoric (HF) acid is used mainly for industrial purposes (e.g., glass etching, metal cleaning, electronics manufacturing). Exposure usually is accidental and often is due to inadequate use of protective measures.

From the tests that were carried out, concrete treated with Evercrete Deep Penetrating Sealer, withstood all of the above acids, accept for the hydrofluoric acid which slightly deteriorated the concrete, but frankly, no other product will withstand hydrofluoric acid.

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2. Does DPS repel Oils and Gasses?
Answer

Firstly we need to understand how does Evercrete DPS work?

When cement sets it forms a chemical reaction with water to provide calcium silicate hydrate which is the chemical producing the strength of cement and concrete. During the hydration process water that is not chemically combined with the calcium silicate dries out within the concrete matrix leaving voids through which water can re-enter and disrupt the concrete or assist in the corrosion of embedded reinforcement. Evercrete DPS penetrates the pore structure of hydrated cement and reacts with the alkalis of sodium and potassium present in the concrete to produce a sodium silicate hydrate, which has both secondary cementing and waterproofing properties. Evercrete In addition it forms a chemical reaction which makes it part of the concrete so once applied it remains for the life of the concrete and cannot be removed unlike silanes and siloxanes which are essentially pore blockers.

It is however important to note that the reactions take place beneath the surface of the concrete, hence the reasons why Evercrete DPS is not visible once it has been applied to the concrete and secondly why it will not affect the bonding between the paint and the concrete.

We wish to illustrate the following:-

The above sketch shows that the Evercrete reaction takes place below the surface.

The molecular structure of concrete is big enough to allow Evercrete DPS to penetrate by capillary suction. This penetration can be up to 2-3cm (depends on the density of the concrete).

In conclusion:

- Since Evercrete DPS forms part of the concrete matrix as explained above it inherits the same characteristics as the concrete and thus will not increase or degrease the concrete’s ability to withstand cold temperatures. The same goes for high temperatures.

- Since Evercrete DPS is a reaction that is taking place below the surface, (see sketch above), and if there is an oil spill, a stain will show up. But what it means is that the oil is only laying on the top surface of the concrete and has not penetrated the actual concrete structure. Evercrete DPS treated concrete will prevent the penetration of oil into the concrete.

- Evercrete DPS treated concrete will allow the concrete to breath, so if the type of gasses are of the same molecular structure than oxygen then it will travel through the concrete but if the gasses have a bigger molecular structure the DPS will block the gasses. In this instance the type of concrete used is also a factor in preventing gasses from travelling through the concrete.

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3. Curing of concrete using DPS?
Answer

Should DPS be applied onto “green” concrete it will definitely help with the curing process and prolong the hydration process; however we do not normally sell DPS as a curing agent. If the client/contractor insists on applying DPS to the concrete it will help with the curing process, and will in most cases prevent the formation of hairline cracks.

However we would normally recommend that you wait at least 28 days or a few weeks/months before the application of DPS as all concrete cracks and when DPS is applied, it can then also be used to seal up those fine hairline cracks.

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4. Damp and wet application of DPS
Answer

The application of DPS on damp or wet concrete is an advantage to enhancing the performance of the product. The reason for this, if the concrete is pre-wet or even damp prior to application then the water molecules would have penetrated the concrete capillaries and would have forced out any air bubbles in the pores, hence helping the DPS to penetrate deeper in the concrete matrix.

So if possible we would recommend that the concrete should be pre-wet prior to the application of DPS (depends on the weather condition). Of course this is not always possible.

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5. Can I paint over DPS?
Answer

Evercrete DPS penetrates below the surface and chemically reacts with the alkali and lime found in concrete. This reaction creates a silica gel membrane within the pores and capillaries of the concrete, permanently sealing it against the ingress of moisture yet allowing the concrete to breathe. Over a period of time the silica gel membrane hydrates and solidifies into a crystalline structure, increasing the hardness and strength of both new and old concrete whilst reducing moisture vapor emissions and permanently stopping the penetration and flow of water and water-borne contaminants such as chlorides and acids, both on the positive or negative side.

It is however important to note that the reactions take place beneath the surface of the concrete, hence the reasons why Evercrete DPS is not visible once it has been applied to the concrete and secondly why it will not affect the bonding between the paint and the concrete.

We wish to illustrate the following:-

The above sketch shows that the Evercrete reaction takes place below the surface.

The prime reason why paint peel or crack off the surface is due to the alkali and lime “fighting” the paint.

The application of Evercrete® DPS to concrete surfaces will give a permanently alkali and moisture free surface for the better bonding of paints. When applied in accordance with the manufacturer’s directions, the paint life on the DPS treated surface can be increased by 300%, providing a longer “fresh paint” appearance and reducing maintenance costs.

Close examination of the concrete surface after Evercrete® DPS is applied, and the surface washed will reveal clean pores. In many cases the DPS has the same effect as “etching” which is usually required prior to applications of paints and adhesives, for better bonding.

Any surface treatment or coating must be removed prior to applying DPS or the DPS will not be able to penetrate the surface. On occasion, foreign matter like oils and grease will be floated to the surface by the DPS as it penetrates the concrete. This foreign matter should be flushed off with water prior to painting. In areas where there is an excessive amount of foreign matter, several cycles of flushing, drying, then flushing again, may be required.

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6. What is the shelf Life of Evercrete DPS?
Answer

Evercrete Deep Penetrating Sealer (DPS) is a water based non-toxic material that contains no solvents or harmful chemicals and as such can be stored for extensive periods, some would even say forever.

However to avoid long term storage we would recommend that Evercrete DPS is used within 2 years of being purchased and we would recommend the following storage requirements:-


- Materials shall be stored in an enclosed cool dry area, protected from direct sunlight.
- The material shall remain in its original sealed containers until time of use.
- The material shall be used as supplied and not diluted.
- If Evercrete DPS becomes frozen, thaw out completely and shake well to fully remix the material prior to using. Freezing will not harm the product.
- Each Evercrete DPS pail has an unique barcode number and hologram and the barcode number can be checked for verification and authenticity on the Evercrete web site.

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7. Evercrete DPS and Carbonation
Answer

Carbonation is a natural process where calcium hydroxide (Ca(OH)2) in the hydrated portland cement paste combines with carbon dioxide (CO2) in the presence of moisture to produce calcium carbonate (CaCO3). Fresh concrete normally has a pH in the range of 12 to 12.5. The pH of the concrete is lowered by the carbonation process. The typical high pH of concrete provides protection from corrosion to embedded reinforcing steel. The most significant effect of carbonation is the lowering of pH and the reduction of corrosion protection afforded to steel reinforcement. Carbonation also results in some shrinkage of the cementitious paste. While this shrinkage is limited to the carbonated layer of paste, it can result in microcracks and cracks which provide opportunities for CO2, moisture, and salt to penetrate deeper into the concrete.

Normally concrete such as 40:50 mpa or higher has a low water content and therefore provides a solid airtight concrete structure. With the application of DPS, which reacts with the free calcium hydroxide (Ca(OH)2) you create an even more air tight environment, where all pores and voids are filled. This reaction is what makes concrete waterproof. It is breathable in the sense that DPS is not a membrane but acts like concrete.

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8. Does Evercrete DPS crack under load?
Answer

Evercrete DPS treated concrete can crack depending upon its mix design and other parameters like static load, linear moving load etc. Evercrete DPS treatment helps to reduce such cracks as it imparts improvement in various physical properties.

If treated concrete cracks, Evercrete DPS does not help unless you use with Evercrete PMC or Evercrete FMC. Considering non abnormal cracks formation viz. hairline cracks less than 0.3mm, Evercrete DPS do work and hence various jobs have been successful completed globally and are performing without any complaints. Besides, considering normal cracking in concrete, Evercrete DPS is being successful used for water tank application where in water is filled all throughout years and variable water load is applicable on DPS treated surfaces. Other applications such as basements, terraces, water retaining structures etc. Considering all normal good concrete tends to crack, Evercrete DPS does have many successful job references. Evercrete DPS does help to stop water leakages if cracks are less than 0.3mm. Also under unavoidable circumstances if cracks are abnormal, then use Evercrete PMC or Evercrete FMC with help of Evercrete DPS, such cracks can also be sealed.

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