How it Works

TechCrete 2500 Waterproofing Agent offers a unique solution to the dilemma of how to protect concrete structures from premature deterioration (by providing excellent waterproofing protection, while also increasing the durability and sustainability of the concrete). This paper provides an overview of the proprietary chemical reaction that effectively waterproofs the concrete itself for the design life of the structure.

NOTE: This one-of-a-kind product was recently voted by the concrete industry as the ‘Most Innovative Product for 2020’ at the World of Concrete Convention held in Las Vegas (category: Materials for Concrete Construction).

Using the spray applied TechCrete 2500 Waterproofing Agent as part of the TechCrete 2500 Waterproofing System, provides complete long-term protection for concrete structures (15-year and 30-year labor and materials warranties are available). This involves performing any necessary cleaning, preparation and repair work, followed by the completion of a 3-step waterproofing application process:

  • Step 1: Spray apply TC 2500 over the entire surface (and allow it to dry to the touch). Then saturate the entire area with water (and let it dry to the touch).

  • Step 2: Spray apply TechCrete Crack & Void Treatment on any visible cracks, and then spray apply TechCrete Accelerating Agent over the entire surface (and allow it to dry to the touch).

  • Step 3: Saturate the entire surface area with water once more.

The TechCrete® Waterproofing System is a modified silicate material that can remain reactive inside the cracks and matrix of concrete for the life of the structure!

STAGE 1:

When TechCrete Waterproofing Agent is applied to concrete, and watered in, it penetrates the concrete and the silcates react with available metallic ions (mainly calcium in hydroxide form). A reaction between Calcium Hydroxide and other ions forms a high-ratio Calcium Silicate Hydrate Gel.

STAGE 2:

As the concrete dries, a reaction between the Calcium Silicate Hydrate Gel & Carbon Dioxide forms low-ratio gel and Calcium Carbonate as a by-product.

STAGE 3:

If a crack forms, water will create a reaction between Calcium Hydroxide and the low ratio Calcium Silicate Hydrate Gel to form a high-ratio Calcium Silicate Hydrate Gel which, with assistance of the Calcium Carbonate by-product, seals the crack helping to prevent further water seepage.

Dynamics:

The foundation is catalytic reactions of which there are two:

1) The calcium carbonate acts as a consolidating “glue” and “space filler” in cracks, pores and capillaries.

2) Calcium Silicate Hydrate Gel plays a vital role – being flexible allows for small dynamic movement such as shrinkage and thermal movement.

When in contact with water, the gel swells, filling remaining spaces and blocking them from allowing water to pass. The TechCrete Wa terproofing Agent, along with its supporting product-line, is able to produce more mass than when originally applied i.e. it “grows” to seal new cracks that develop after application!

Once the TC 2500 has been applied and watered in (Step 1), a chemical reaction will begin to occur, that creates a protective waterproofing gel. The chemical reaction that forms this gel occurs ½” – ¾” below the surface of the concrete, and prevents any water, chemicals, chloride ions, etc. from reaching the steel reinforcement bars that were placed in the concrete during construction of the structure. This gel does not form on the surface of the concrete, and does not change the appearance or the slipperiness coefficient of the concrete surface. The concrete surface looks the same after the waterproofing application as it did before the application.

NOTE: Paint, coatings, paving asphalt, etc. can be applied to the surface of the concrete following the completion of the waterproofing system (if desired).

THE CHEMICAL REACTION

The following components are necessary for this biochemically modified silicate gel to form just below the surface of the concrete, and those components are:

  • TechCrete 2500 Waterproofing Agent
  • Calcium (readily available in the concrete)
  • Water
  • Carbon Dioxide

TC 2500 penetrates below the surface of the concrete during the initial application, and remains reactive inside the matrix of the concrete indefinitely. As future cracks occur, rainwater will reactivate the chemicals, forming new gel and sealing the cracks as they occur. Stable cracks up to 2.0 mm in width will be sealed during the application of the waterproofing, and future cracks up to 0.4 mm in width will be sealed for the remaining life of the structure. Any stable cracks that are wider than these dimensions, and any structural or moving cracks must be properly repaired as outlined in the Alchemco repair procedures.

TC 2500 has a unique and proprietary, biochemically modified catalyst that separates it from all other spray applied concrete sealers and waterproofing products. A catalyst is a material that enables, speeds up or slows down a chemical reaction, without changing the chemical reaction itself. When TC 2500 is used to waterproof a concrete structure, there are two distinct catalytic reactions that occur, creating a ‘virtuous cycle’ that continually repeats itself over and over for the remaining life of the structure.

TC2500 is primarily made up of silicates, combined with this proprietary biochemical catalyst. During the three application steps, the silicates within TC 2500 react with metallic ions in the concrete (primarily the calcium hydroxide that is a by-product of cement hydration). During this stage, TC 2500 is highly reactive, and creates a complex Calcium Silicate Hydrate (CSH) gel. This gel swells when it comes in contact with water (blocking cracks, pores, capillaries, voids, etc.) reducing the permeability of the concrete and preventing the penetration of water.

Over time, Carbon Dioxide from the atmosphere extracts some of the Calcium from the CSH gel to form Calcium Carbonate. This creates an inert mass that further reduces the permeability and porosity of the concrete, by permanently blocking the cracks, voids, micro-fractures, etc. However, the ‘carbonation of concrete’ problem that is usually associated with Carbon Dioxide, is not a problem for TechCrete 2500.

THE LIFETIME CYCLE: In order for TC 2500 to seal all future cracks that form after the application, it must produce more mass than was originally applied … in other words it must ‘grow’. When Carbon Dioxide in the atmosphere extracts some of the Calcium from the waterproofing gel, it leaves a ‘low ratio’ CSH gel. As a result of this interaction, the waterproofing gel is now ‘ready to react’ again, and actively looks to attract Calcium ions to bring it back into equilibrium. So, when water enters the concrete, the cement continues to hydrate, and through the process of diffusion within the concrete, the Calcium moves from areas of high concentration to areas of low concentration. The ‘low ratio’ CSH gel then reacts with the newly available Calcium and once again becomes a ‘high ratio’ CSH gel. At this point, the cycle begins all over again with the ‘high ratio’ CSH gel reacting with Carbon Dioxide in the atmosphere, once again forming Calcium Carbonate, which permanently plugs the cracks, pores, microfractures, voids, etc. (once again leaving a ‘low ratio’ CSH gel).

This ongoing chemical reaction creates a dynamic and reliable self-healing process within the concrete. The process of ‘carbonation’ is normally considered detrimental to concrete, because it lowers the pH level of the concrete (which deteriorates the protective ‘passive layer’ surrounding the steel reinforcement bars, and allows corrosion to occur). TechCrete 2500 Waterproofing Agent does not have this problem. It creates a ‘virtuous’ carbonation cycle which does not lower the alkalinity level of the concrete, but in fact increases the alkalinity level, thereby enhancing the protection of the steel reinforcement. In addition, the Calcium Carbonate that is formed during this carbonation cycle increases the long-term durability of the concrete.

The difference between TechCrete 2500 and normal silicate products is that the biochemical catalyst allows this carbonation cycle to repeat itself indefinitely. Plain silicates get stuck when they go thru the carbonation process, and are not available later to react again. As a result, normal silicate products are not even able to seal ‘existing cracks’, much less any ‘future cracks’ that will occur.

Also, the fact that there are two reaction components that occur when using TC 2500 is important. The Calcium Carbonate that is formed acts as a consolidating glue or space filler, in the cracks, pores, capillaries, etc. The CSH gel also plays a vital role, because not only does it allow the virtuous cycle to occur over and over (a Calcium Carbonate factory), but this colloidal gel is not rigid like crystalline technology products are; so it allows for small dynamic movement such as shrinkage or thermal movements in the concrete.

In summary, when TC 2500 comes in contact with water it forms a waterproofing gel that swells; filling and blocking off the spaces (cracks) that allowed the water to enter.Then the ‘factory’ gets to work depositing Calcium Carbonate to permanently seal it.The waterproofing gel will then remain ‘dormant’ until water comes in contact with it again.

FAQ - Also known as CretePro 101

1. Is it important to do all of the ‘waterings’ in a timely manner?

After the application of TechCrete 2500 Waterproofing Agent becomes dry to the touch, the first watering is absolutely CRITICAL!
If the product is not watered within 6 hours of being applied, the system is lost and the TechCrete 2500 Waterproofing Agent material is no more useful than a floor hardener.
The following days’ waterings (Day 2 watering or Accelerating Agent…and Day 3 watering) can be conducted at any time. The fact is it will usually take watering every day for 3 days (or using Accelerating Agent the second day) to promote sufficient modified silicate gel growth in cracks to achieve a 100% watertight result.
Once TechCrete 2500 Waterproofing Agent is touch dry, it is not possible to water it too much. In fact, you could dam the area and allow the cracks to leak water until they totally seal over the next 2-3 days.

2. In addition to providing a low-cost application, what other benefits does TechCrete 2500 provide?

The benefits of using TechCrete 2500 Waterproofing Agent are varied & significant.
Low cost application – TechCrete 2500 Waterproofing Agent can be applied very quickly & efficiently compared to most other waterproofing products.
Fast Track Construction – Often in wet weather conditions, the need to have all moisture removed from the concrete prior to applying a waterproof coating or membrane on the surface, can add significant time delays. By comparison TechCrete 2500 Waterproofing Agent can be applied as soon as concrete surface is visually dry.
No Damage – Once TechCrete 2500 Waterproofing Agent is applied and dries sufficiently (maximum 6 hours), it cannot be damaged by the other trades working on site.
Construction & Engineering Savings – For example TechCrete 2500 Waterproofing Agent applications on parking structures, is applied directly onto the structural slab.
This avoids the need for a structural topping slab, which saves time & money.
• The same is true for bridges where a topping slab is not required over the TechCrete 2500 Waterproofing Agent…since ballast stones can be placed directly over the waterproofing product.

3. Can TechCrete 2500 Waterproofing Agent be applied over an area where a crystalline growth waterproofing product was previously used?

Yes, quite often crystal admixtures which have been inappropriately applied above grade (shaker method) continue to form cracks which are not sealed…and continue to leak.
TechCrete 2500 Waterproofing Agent can permanently repair such failed applications… due to the superior crack sealing properties of its modified silicate gel

4. Can TechCrete 2500 Waterproofing Agent damage building materials?

Since TechCrete 2500 Waterproofing Agent has a high pH level (11.7) similar to concrete itself… contact with aluminum, glass, and glass glazed tiles should be avoided.
NOTE: It is very IMPORTANT to make sure any overspray does not come in contact with such materials…this of course also includes car paintwork.

5. How deep does TechCrete 2500 Waterproofing Agent penetrate into the concrete?

TechCrete 2500 Waterproofing Agent has shown 1/2-inch to 2/3-inch average penetration below the surface, when used on highway grade concretes (5,800 psi). Additional testing has shown an average 3/4 inch penetration when applied to 4,600 psi concrete.

6. Is TechCrete 2500 Waterproofing Agent suitable to waterproof all types of concrete?

TechCrete 2500 Waterproofing Agent will provide excellent waterproofing properties in most cementitious concrete mixes. Suitable concretes types include OPC, PPC Ash free blends, Type C ash blends and slag blends. Concrete mixes containing silica fume should be limited to 8% cement replacement.

7. Does TechCrete 2500 Waterproofing Agent increase the durability of the concrete?

TechCrete 2500 Waterproofing Agent is an excellent long-term waterproofing solution, that extends the useful life of the concrete structures considerably.
Areas treated with TechCrete 2500 Waterproofing Agent will prevent concrete from spalling, and defend against the effects of freeze/thaw and de-icing salt damage.
Testing demonstrates that applied areas experience an increase in hardness from 6 to 8 on Moh’s scale (a hardness rating of 8 is equivalent to granite).

8. What happens if it rains during the application of the TechCrete 2500 Waterproofing Agent?

It is CRITICAL that TechCrete 2500 Waterproofing Agent gets absorbed into the concrete through capillary action, which is possible when the concrete surface becoming dry to the touch before watering.
NOTE: Should rain fall on TechCrete 2500 Waterproofing Agent before it dries to the touch…it must be assumed that another application will be required once the concrete has become dry once again.

9. Is TechCrete 2500 Waterproofing Agent environmentally friendly?

TechCrete 2500 Waterproofing Agent is one of the most environmentally safe waterproofing technologies available in the marketplace.
TechCrete 2500 Waterproofing Agent is certified as acceptable for use in potable water tanks and additionally has been utilized in marine aquarium projects (using salt water).
NOTE: product has international potable water certifications, and is currently being tested at Underwriters Laboratories for certification in the United States. (UL: NSF-61)

10. What happens if the product is not ‘watered in’ to specification?

When TechCrete 2500 Waterproofing Agent is applied and becomes touch dry (2-6 hours) a first watering is absolutely critical for TechCrete 2500 Waterproofing Agent to function properly.
The second and third specified waterings are to allow sufficient product expansion inside the concrete to seal both the matrix and any cracks present at the time of application..

11. Is TechCrete 2500 Waterproofing Agent ‘UV Stable’?

Yes. Since TechCrete 2500 Waterproofing Agent forms its waterproofing gel below the surface of the concrete…it is not affected by UV radiation.

12. What effects do high & low temperatures have on TechCrete 2500 Waterproofing Agent’s waterproofing performance…and re-sealing capabilities

TechCrete 2500 Waterproofing Agent must be applied above 40°F to ensure there is no moisture frozen inside the concrete that is being treated. Furthermore, TechCrete 2500 Waterproofing Agent can only react with free calcium and water to create its chemical seal when the temperature is 40°F or above.
TechCrete 2500 Waterproofing Agent should not be applied at temperatures above 95°F as the product will begin to atomize into the atmosphere, and could begin to dry on the concrete surface prior to capillary absorption.
Once TechCrete 2500 Waterproofing Agent has been properly applied…and dries to the touch, temperature becomes irrelevant. This makes the product suitable for use in sub-zero temperatures or high-heat conditions. The waterproofing formula has been proven over the course of many projects that
were completed in areas of intense heat and freezing temperatures.

13. How soon can TechCrete 2500 Waterproofing Agent be applied to newly poured concrete?

We recommend allowing any newly poured concrete to cure for a minimum of 28-days prior to TechCrete 2500 Waterproofing Agent being applied.
However, TechCrete 2500 Waterproofing Agent can be applied in as few as 14 days after the new concrete is poured, UNDER CERTAIN FAVORABLE WEATHER CONDITIONS. Contact the Alchemco Technical Department to discuss the necessary weather conditions for this to occur, on a project-by-project basis.
If the 28-day period is reduced in any way, the applicator must be prepared to re-visit the project after 28 days from the pour date, to ensure that no new major cracks have formed which may require repair and/or re-application of TechCrete 2500 Waterproofing Agent

14. How does TechCrete 2500 Waterproofing Agent prevent salts and other contaminants from reaching the steel reinforcements?

TechCrete 2500 Waterproofing Agent uses water to waterproof in a similar manner to the way Volclay (volcanic bentonite clay) reacts. Only instead of being on the surface, TechCrete 2500 Waterproofing Agent is creating its waterproofing barrier below the concrete surface.
Given that tests confirm a 1/2 inch to 2/3 inch product penetration in 5,800 psi concrete, any water or salts that penetrates the first 1/10 inch is of no concern to the structure’s durability (since steel reinforcements are generally designed to be at least 1 inch below the concrete surface).

15. Does TechCrete 2500 Waterproofing Agent treatment help prevent accelerated corrosion or other damage to steel reinforcements?

Cementitious concretes are highly alkali in nature (which is what delivers passivity to the steel), preventing it from rusting. The high pH of TechCrete 2500 Waterproofing Agent functions in exactly the same protective way. In fact, the combined application of TechCrete 2500 Waterproofing Agent and TechCrete Accelerating Agent actually improves the alkalinity of ‘alkali depleted’ concrete structures.

16. Does TechCrete 2500 Waterproofing Agent trap moisture in the concrete?

NO. TechCrete 2500 Waterproofing Agent allows for moisture vapor outgassing while preventing both the ingress of water molecules and pollutants from reaching any steel reinforcement. IT IS BREATHABLE!

17. If it has been raining how do I know the concrete is dry enough to treat?

Providing the surface is dry to the touch, TechCrete 2500 Waterproofing Agent may be applied. If TechCrete 2500 Waterproofing Agent is applied to wet concrete or concrete with damp spots, the product will not be absorbed into the concrete thru capillary action.
This means that any damp spots treated with TechCrete 2500 Waterproofing Agent would simply see the product “not absorb” into the concrete, and it will wash away during the first watering procedure.

18. Can coatings and/or paints be applied in areas treated by TechCrete 2500 Waterproofing Agent?

YES! The effective chemicals that make up TechCrete 2500 Waterproofing Agent migrate into the concrete, and form a sub-surface waterproof gel there. As a result, the surface can be coated or painted once the full waterproofing application has been completed.
However, it is important to understand that TechCrete 2500 Waterproofing Agent’s is a water activated product, whose ‘self-healing’ properties (to seal future cracks) are dependent on water seeping into the concrete when a new crack occurs. This interaction of water, the calcium hydroxide present in the concrete, and TechCrete 2500 Waterproofing Agent is what forms additional gel to seal new cracks. In areas where paint or a surface coating has been applied (in addition to our waterproofing materials) that inhibits the penetration of future water into the concrete…our product’s ‘self-healing’ process cannot take place.

19. What happens if the concrete cracks after achieving a watertight treatment applying TechCrete 2500 Waterproofing Agent?

Rainwater itself will activate the ‘self-healing’ properties of the product to take place within a couple of days, so no remedial repairs should be required. TechCrete 2500 Waterproofing Agent is re-active in concrete, and will repair any future cracks up to a width of 1/64 inch (0.4 mm).

20. Can TechCrete 2500 Waterproofing Agent be applied on projects where other waterproofing ‘sealer’ materials have been used previously?

Any material designed to repel water from concrete will also repel TechCrete 2500 Waterproofing Agent (stopping it from migrating into the concrete), and thereby preventing the waterproofing reaction from taking place.
In order to use TechCrete 2500 Waterproofing Agent on these projects, all previous failed waterproofing materials (coatings, membranes, etc.) must be completely removed prior to application. If cracks have been contaminated by previous materials, they may require an arrow head grind to make sure all of the previously applied waterproofing sealer has been removed. TechCrete Patch & Repair (to repair cracks too large for the gel to bridge) and TechCrete Waterproofing Agent can then be used.

21. What is the best way for newly poured concrete be cured, prior to TechCrete 2500 Waterproofing Agent application?

The preference is that water curing practices be used, which guarantees no form of concrete contamination. However, if high quality curing agents are specified, then they must be removed using power washing or shot blasting, in order for TechCrete 2500 Waterproofing Agent penetration to occur during application.

22. Is TechCrete 2500 Waterproofing Agent compatible with other waterproofing products used during the installation of expansion joints, or the detailing of penetrations, etc.?

As TechCrete 2500 Waterproofing Agent produces Calcium Silicate Hydrate gel, all concrete products will adhere to TechCrete 2500 Waterproofing Agent treated concrete.

23. Does TechCrete 2500 Waterproofing Agent attract dirt or air borne pollutants onto treated concrete?

TechCrete 2500 Waterproofing Agent as a silicate material, creates no electrostatic attraction for airborne pollutants. The opposite can apply to sealer materials in particular siliconate based materials.

24. How well does TechCrete 2500 Waterproofing Agent prevent foreign materials such as fuel, oils and grease from penetrating into the concrete…and do these materials adversely affect the TechCrete 2500 Waterproofing Agent’s performance?

These materials are unable to penetrate into concrete that has had a proper application of TechCrete 2500 Waterproofing Agent.
Furthermore, these materials cannot adversely affect the TechCrete 2500 Waterproofing Agent’s performance.

25. How does TechCrete 2500 Waterproofing Agent compare to other waterproofing sealer materials such as Silanes, Siloxanes and Methyl Methacrylates?

Generic sealers such as Silanes, Siloxanes, Methyl Methacrylate’s (and even Silicates) can only deliver general & temporary concrete protection, without addressing the issue of ongoing concrete cracks.
Sealers are most often used as a general preventative for freeze/thaw damage, ingress of airborne pollutants and some protection from de-icing salts.
A 2-coat, 100% solids Silane waterproofing product will have a substantially higher installed cost than a single application of TechCrete 2500 Waterproofing Agent.

26. Are there areas where you should not apply TechCrete 2500 Waterproofing Agent?

TechCrete 2500 Waterproofing Agent requires capillary suction into dry concrete prior to the application of the first t ‘watering in’ procedure. Therefore TechCrete 2500 Waterproofing Agent cannot be applied to wet concrete, whether it’s simply damp or has water permeating through it.
TechCrete 2500 Waterproofing Agent should not be applied to any concrete surfaces where the general matrix and/or cracks present have been contaminated with any water repellent materials (they must be removed prior to application of our product). Obviously if water cannot absorb into the concrete, then neither can TechCrete 2500 Waterproofing Agent.
TechCrete 2500 Waterproofing Agent is generally suited to all “ABOVE GRADE” applications including all dams, bridges, parking structures, water treatment plants, stadiums, water holding vessel applications, etc..

27. Will TechCrete 2500 Waterproofing Agent change the appearance of concrete either immediately after the application, or in the long term?

When TechCrete 2500 Waterproofing Agent has been applied to concrete, watered and allowed to dry, a trained eye will notice a slight increase in sheen given off by excess surface silicates.
Over the long term there will be no visual changes what so ever including any form of discoloration.

28. Is TechCrete 2500 Waterproofing Agent similar to a ‘crystal growth’ waterproofing product?

TechCrete 2500 Waterproofing Agent is often compared to crystal growth materials however, they have totally different chemistries & technologies.
Crystal growth materials produce rigid dendritic crystals to block water molecules.
By comparison TechCrete 2500 Waterproofing Agent forms an amorphous gel below the surface of the concrete…including any cracks the are present.at the time of application.
The amorphous gel can be cyclically opened & closed in watertight cracks of up to 5/64 inch (2.0 mm) wide…and will tolerate a 1/64 inch (0.4 mm) opening & closing cycle on future cracks going forward – without leakage through the slab.

29. What type of spray equipment is required to apply TechCrete 2500 Waterproofing Agent onto concrete?

Small applications can be undertaken with the use of a simple backpack sprayer (manual or electric) delivering up to 3,000 sq.ft. per hour. For larger projects an impeller driven on demand pump hooked up to deliver 8,000 sq.ft. per hour per unit.

30. What level of water pressure will TechCrete 2500 Waterproofing Agent handle prior to failure?

Concrete treated with TechCrete 2500 Waterproofing Agent has been successfully tested to a pressure of 1.300 feet (400 meters).
TechCrete 2500 Waterproofing Agent has successfully been used on projects involving ponds, pools, water parks, and other similar projects where the concrete is under constant water pressure. It has even been used to waterproof a concrete ‘floating dry dock’ in Hawaii…where the treated portions of the dry dock have been continuously submerged in salt water (24/7) for years, with no leaks.

31. Can you use TechCrete 2500 Waterproofing Agent on an existing topping slab which leaks?

TechCrete 2500 Waterproofing Agent waterproofs all cementitious concretes, including reinforced topping slabs.
While TechCrete 2500 Waterproofing Agent will waterproof the actual topping, all too often water paths can remain under the topping transmitted by failed penetration detailing, wind driven rain external to the building, electrical conduits, parapet wall deck interfaces from the outer edge etc. etc.
Only treat topping slabs at your own risk, fully understanding the intrinsic problems which may be encountered post TechCrete 2500 Waterproofing Agent application due to other unknown problems existing under the topping.

32. What happens when TechCrete 2500 Waterproofing Agent is used to treat concrete with unstable working cracks (due to structural volatility)?

In many cases, these projects are ‘under engineered’ parking structures, where vehicular loading is contributing to structural movement. For these applications TechCrete 2500 Waterproofing Agent is the primary concrete waterproofing material and volatile cracks are addressed by utilizing TechCrete PolySeal Sealant in the volatile cracks to accommodate movement without failure.

33. What special steps should be taken on projects with old/weathered concrete slabs that have leaked for many years?

Alchemco recommends applying TechCrete Accelerating Agent (average rate of 200 sq.ft. per gallon) over the entire surface. When used in combination with TechCrete 2500 Waterproofing Agent, this will insure the proper generation of the sub-surface waterproofing layer.

34. How do you know that sufficient product is being applied during spraying?

The average application rate is 200 sq.ft. per gallon…and in many cases, the applicators will section off portions of the area to be treated, using 5-gallon
pails of product spaced every 1,000 square feet.
During the course of a TechCrete 2500 Waterproofing Agent application, the applicator should see product flowing on the surface of the concrete. Simply misting the surface without saturation is deemed ineffective.

35. Can TechCrete 2500 Waterproofing Agent waterproof cold or pour joints without using Waterstop or other detailing work?

Yes, however for Existing Structure projects, Alchemco strongly recommends the applicator does not rely solely on the TechCrete 2500 Waterproofing Agent in these areas. Please see in the TechCrete Installation Details, where it refers to the use of TechCrete PolyMembrane Flashing for these types of
cases.
For New Construction projects, Alchemco strongly recommends the use of TechCrete Waterstop Strip (and Adhesive) on cold joints or pour joints (when the concrete is being poured).

36. What happens if a previously leaking crack continues to leak after a TechCrete 2500 Waterproofing Agent has been applied?

One of great features of TechCrete 2500 Waterproofing Agent is that if a leak is still present at the end of an application, the matter can be easily
addressed.
Unlike a membrane application where water can track underneath the membrane (and show up somewhere else), with a TechCrete 2500 Waterproofing
Agent application one can go straight to the offending crack for remedial treatment.
In some instances, just the addition of more water (promoting more gel growth) will alleviate the situation.
In other cases, the problem may require applying tape to the underside of the concrete slab, so that TechCrete 2500 Waterproofing Agent can be flooded into the crack, then further watered to achieve a 100% watertight result.

37. What effect, if any does TechCrete 2500 Waterproofing Agent have on the bonding ability of cementitious materials?

The TechCrete 2500 Waterproofing Agent bond wrench test shows a 27% plus bond increase between cementitious materials.

38. Is TechCrete 2500 Waterproofing Agent suitable for waterproofing pre-cast panels and pre-cast elements?

Yes! But quite often the “form release agents” that are used by the pre-cast manufacturers may be a wax or oil base…which will prevent the TechCrete 2500 Waterproofing Agent from penetrating.
Before treating pre-cast elements with TechCrete 2500 Waterproofing Agent there must be no residual form release agent present, as this would repel TechCrete 2500 Waterproofing Agent penetration.
Also, residual release waterproofing agent could cause “white stains” on the concrete. If in doubt, a trial application id the recommended first step.

39. What precautions should be taken if TechCrete 2500 Waterproofing Agent is being sprayed in an enclosed area…such as a water tank?

Getting TechCrete 2500 Waterproofing Agent to the point where it is ‘touch dry’ prior to the first watering may require air blower units, to help speed up the process.
Even though TechCrete 2500 Waterproofing Agent is non-toxic…a breathing apparatus will be needed in some enclosed applications.

40. What is the shelf life of TechCrete 2500 Waterproofing Agent?

As long as the lid on the container remains sealed (preventing air intrusion) TechCrete 2500 Waterproofing Agent maintains a virtually unlimited shelf life. However, the product should always be mixed prior to application…since the solids can settle to the bottom of the container over time.

41. Does TechCrete 2500 Waterproofing Agent promote fungal growth (mold) on treated concrete?

Since TechCrete 2500 Waterproofing Agent is a high pH product (11.7) it will prevent or deter fungal growth occurrence.
In damp shaded areas where fungus will eventually grow on TechCrete 2500 Waterproofing Agent removal of the fungus is extremely easy, since the spores are unable to penetrate into the concrete.

42. Can TechCrete 2500 Waterproofing Agent be used in a negative pressure situation?

Yes, but only if the area to be treated is totally dry, in order to allow capillary absorption and then the regularly scheduled waterings (which must take place on the negative side, prior to water moving back from the positive side). Even though the water will be prevented from coming thru the negative side concrete surface, it can accumulate inside the concrete slab…since the positive side surface can still be leaking. This could trap water in the slab, and ultimately deteriorate the concrete prematurely.

43. If TechCrete 2500 Waterproofing Agent becomes frozen in its container, does this destroy the performance ability of the product?

If TechCrete 2500 Waterproofing Agent becomes frozen in its container, it is essential that the product is “slowly” warmed to around 40 degrees Fahrenheit.
The product should then be stirred thoroughly…before using it for application.
Also, be aware that the warmer the temperature of the concrete, the faster the TechCrete 2500 Waterproofing Agent will react with any free calcium in the concrete.

44. Does TechCrete 2500 Waterproofing Agent accelerate the negative effects of AAR (Alkali Aggregate Reaction) or ASR (Alkali Silica Reaction)?

Most Silicate based sealers, being highly alkali in nature increase the rate of AAR/ASR concrete deterioration. However, TechCrete 2500 Waterproofing Agent stops AAR/ASR concrete expansion totally…by stopping water’s entry into the concrete slab, that’s critical to this ongoing reaction.

45. What happens if hot asphalt is applied over concrete surfaces that have been treated with TechCrete 2500 Waterproofing Agent?

Hot asphalt (320°F) applied over a concrete slab that has been treated with TechCrete 2500 Waterproofing Agent will have no detrimental effect.
The asphaltic bond test shows no bond loss when placed over the control and TechCrete 2500 Waterproofing Agent treated samples. Of course, it is critical that proper asphalt application procedures are followed, in particular the placement of the “tack coat” prior to asphalt placement.

The cycle continues so long as water, calcium or other ions and carbon dioxide are available!

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