Mitigation of Concrete Slab Chemical Vapors

January 29, 2020

How do I stop chemicals gas vapors from contaminated soils passing though a concrete slab? This is a question I get frequently from owners and environmental mitigation experts.

Background

Chemical contamination vapors tend to pass though a concrete slab and get into the air above. Stopping the migration of the gas through a slab is frequently a requirement of repurposing a space.

The following steps can be used to mitigate chemical vapors into your space above it. Without the right tools these vapors in the air from contamination under that slab can be quite pervasive.

Each job needs to be evaluated on an individual bases. The tools below make the solution less evasive.

Cracks through the Concrete Slab

The most direct way for soil contamination gasses to get in is through cracks. Cracks are the path of least resistance, so most of your vapors come through cracks in the floor. That is a very easy fix Product #684LV – Methyl Methacrylate Crack Healer and Sealer.

The #684LV has about the viscosity (thickness) of diesel fuel. That makes it easy to gravity feed into small cracks small porous areas of the concrete. It welds the cracks back together with a bond strength that is greater than the tensile strength of the concrete. In other words structurally you have the monolithic structure that the concrete was intended to be.

Expansion Joints

Expansion joints are the also a very direct route for vapors to come in. To seal these joints use Product #632 – Chemical Resistant Joint Filler. This is a highly chemical resistant joint filler. It will not only keep the vapors out. If there is going to be a chemical exposure to the surface there will it will stop the chemicals from attacking your concrete and further contaminating the soils below it.

Sealing the Surface of the Concrete Slab.

The next step is to prime the concrete with Product #12 Chemical Resistant Primer / Sealer.

This is where there is a couple of ways to go. You can apply an additional coat or coats of the #12 or go on to Coating the Concrete Slab below. Our optional translucent Synthetic Anti-Skid Fine may be added to the #12 if it is used in additional coats as a clear sealer.

The Product #12 Primer Sealer can also be mixed with silica sand and used as a patching material for potholes and otherwise damaged concrete if required.

Coating the Concrete Slap 

In many cases you will want to install a coating over the concrete slab.  There are a number of options for doing this but here are a few of the most common ones.  The biggest difference between these coatings is the chemical resistance. Please See Chemical Resistance Chart for a comparison of chemical resistance of the products below. All of these products are 100% solid, zero voc.  All of the coatings in this section are highly durable and resist the abrasion of traffic. 

UV Resistant Top-Coating

For jobs that will see direct sunlight.  It may be desirable to add an ultra violet (UV) Resistant top coating for the systems above.  

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Posted by Norm Lambert

Epoxy Mortar Installation

June 19, 2019

Epoxy.com Mortar Systems can be used to make permanent repairs that no other kind of product can make. The purpose of this blog is to give you an overview of what you can use and how to use it.

  1. Product Selection –  The following are a list of Epoxy.com Products that make excellent epoxy mortars  All the products listed below are zero (0) VOC, so it meets even the strictest low VOC requirements, and meets Indoor Environmental Quality/Air Quality (LEED IEQ 4.2 Indoor Emitting Materials Credit). See the individual product component technical data sheets and MSDS for further information.
  2. INSTALLATION:
    • First and foremost is good surface preparation.  Good surface preparation is necessary for most if not all patches to have long term success: www.epoxy.com/surfaceprep.aspx.
    • Prime the bottom of the whole with some of the neat mortar resin. Neat mortar resin is the liquid (A&B) mixed at the proper mix ratio and stirring in a way to insure a completely mixed product.  This will typically take about 3 minutes.
    • Mix some of the neat epoxy into the Epoxy.com Mortar Blend Aggregate #82 or other appropriate dry clean silica sand gradation.
    • The amount of sand aggregate depends on the aggregate used. 
      • Typically, the Epoxy.com Product #82 Mortar aggregate can be added at a rate of 18 to 27 lbs. of #82 per 1.5 Qt of mixed resin (1Quart of A to ½ Quart of B).
      • You will need to recalculate the sand above when using a different sized batch. This is doubly true if using one of or 4:1 mix ratio material.
      • Shallow patches tend to be a smaller amount of sand filler.
      • Deeper patches tend to be on the higher side.
      • If you get a lot of resin to the surface your mix is too wet.  If your mixture after it hardens is porous, or weak then you have added too much aggregate.
      • For a better finish in very deep pours do it in 2 lifts. 
        • Fill all but the last ¼ inch plus or minus with your dryer mix. Allow to cure hard (typically overnight).Fill with a wetter mix on top of that after the first one has cured.
        • To ensure proper adhesion between layers never wait more than 24 hours between layers.
      • It is always better to have your patch slightly higher rather than to low.  If you are slightly high you can grind the patch back to level. If to low you will need to fill again. 
    • For very shallow fills (1/32 or so) where the sand particles are to large you can use any of the following:

As always, when in doubt contact me at Epoxy.com Technical Support with your questions.

norm@epoxy.com
1-352-533-2167

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Posted by Norm Lambert

Patching Floor with Epoxy

July 18, 2017

Here is an outline of the procedure for patching with Epoxy.com Product #1 and Product #10.  Cold cure is identical but you should make even smaller batches and work even faster.

  1. Mix a small amount of the #10 (mix ratio 2A: 1B).
    1. Measure accurately and mix for 3 minutes with a proper size mixer.
    2. Typically very small batches less than a quart can be mixed with a stir stick.
    3. Larger batches should use a mixing paddle in a low speed drill or similar. Typically  mixing paddles are 5 inches or more in diameter.
  2. Apply a primer coat of #10 at a rate of 250-300 SF per gallon (typically done with a roller) to the substrate the mortar is to be attached to.
    1. Typically you will allow this to harden to the touch to make troweling into it easy.
    2. You can trowel into the wet primer in the case of small patches.
  3. Mortar Patch
    1. Mix another small batch of #10, using the methods in step 1 above.
    2. Add Product #82 Mortar Blend Aggregate to the mixed resin in 3a. You can add as much as 50 to 75 lbs. of mortar blend aggregate to a gallon of mixed #10 resin. If the material appears to wet you can add more, if it is too dry add less.
    3. Quickly trowel the patch into place.  Winter Cure Epoxy can set very fast in the bucket.
  4. Sealer Coat
    1. After the patch in step 3 has hardened, you can grind off any high spots and fill more material again if needed.
    2. Then seal the top of the patch.
  1. Product #10 is thinner than the #1, making it an excellent sealer for sealing up the patch.
  2. Alternately you can go directly to a very thin coat of #1
  1. Top Coat
    1. Mix small batches of #1 using the methods used in #1 above.
    2. Mix optional Antiskid fine into the coating above at a rate of 8-16 volume ounces of Anti-skid per gallon of mixed resin.  12 ounces per gallon is typical.  This is done by mixing the resin first, adding the anti-skid and mixing for another min.
    3. Quickly apply the material with a roller at a rate of 160-200 SF per gallon per coat.  Two coats is recommended.
  2. Please read all the information below before starting your project.
  1. Do with Epoxies
  2. Don’ts with Epoxies
  3. Surface Preparation
  4. www.epoxy.com/10.aspx
  5. http://epoxy.com/1cold.htm
  6. SDS Product #10 Part A – Hardener Lo-Mod Epoxy Adhesive and Mortar Epoxy Resin
  7. SDS Product #10 Part Cold Cure B – Lo-Mod Epoxy Adhesive and Mortar Epoxy Hardener
  8. SDS Product #1A – All Purpose Coating Hardener Component MSDS.
  9. SDS Product #1B -cc – Cold Cure Epoxy Hardener for Product #1

 

BE SURE TO CALL ME WITH ANY QUESTIONS OR CONCERNS!

 

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Posted by Norm Lambert

Epoxy Injection of Structures Part 3

February 24, 2017

This is the third in a series on Infrastructure Repairs Using Epoxy. Part One is  Introduction to Epoxy Injection.  Part 2 is Crack Analysis Before Epoxy Injection

If your have not read that yet you may want to go back and read it before you proceed with reading this.

Port Setting

It is extremely important that if drilling to use the right tool. to set drill type ports use a vacuum swivel drill. That is a drill with vacuum attached swivel drill chuck and hollow a drill bit.

Concrete dust can be detrimental to the injection processes in several ways. Any dust remaining in the drill hole near a crack can combine with the very low viscosity injection resin. This thickens your resin turning it into a weak paste. This paste can slow or even block the resin flow. Drilling very tight crack with a solid drill forces dust into the crack. This seals the crack from resin flow. Do not allow shortcuts in the drilling procedures!  However, for most applications the surface port is the easiest and most effective method.Epoxy Injection Surface Port

Port Spacing

Determining the spacing of ports is done by a highly experience applicator. This spacing is a factor of the tightness of the crack and the depth of the concrete substrate. Spacing is normally between four (4) and eight (8) inches.

Port Setting and Sealing

Align ports directly over cracks. That allows injection resin to flow into the crack. Seal surface cracks. Sealing the exterior of cracks is done with Epoxy Gel type Bonder.

Testing The System

Test cracks that are ill defined, or if dust or debris is in the crack. This testing may be done by injecting water into the crack area.

Water left in the cracks will not effect the injection process or the curing of the Epoxy.com Injection Resin. Heavier injection resin forces the water out the cracks. Water injection helps clean the cracked areas. More important, is that it helps avoid the unexpected. This process of flushing the cracks is commonly skipped by more experience contractors, who can tell if there will be a flow of resin, by just looking at them. However, when in doubt water testing is a must.

If the cracks contain algae, chlorinated water containing copper sulfate is injected. After pumping this mixture is left over night. The next morning the crack is flushed by pumping fresh water, into it. This flushes it out before resin injection begins.

Efflorescence builds up on the bottom of a crack in a horizontal slab. Water in the crack extracting soluble calcium hydroxide is the cause. The water evaporates at the surface leaving the lime, which later reacts with the carbon dioxide in the air to form limestone. The inside of the crack, is frequently free of limestone and making it suitable for injection.

Part 4 of this series: Injection Resin Materials Product Selection.

For more information visit our website at http://www.epoxy.com, email us at info@epoxy.com or call our technical service department at +1 (352) 533-2167.

 

1 Comment | adhesive, Bridge Concrete Repair, Concrete Bridge Pier Repair, Concrete bridge repair epoxy, concrete dam repair, concrete infrastructure bridge repair, Concrete Infrastructure Repair, Concrete Repair, concrete wall repair epoxy, Epoxy, epoxy concrete repair, epoxy injection, Infrastructure Repair, Injection, Installation, repairing concrete with Epoxy | Tagged: , , , , , , , | Permalink
Posted by Norm Lambert

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