Tombstone Repairs with Epoxy

August 22, 2012

A technician who uses a non-Epoxy.com product to repair tombstones wrote me recently looking for help with problems that he was having.  He goes on to say that the epoxy that he uses never fails, but rather the stone fails. When a secondary break occurs, the stone always re-breaks about 2 mm (about ¾ inch) above or below the epoxy joint.  The epoxy attached to about 2 mm of the stone and holds well.

He asked me if the epoxy shrinks so much that it will ‘ pull away ‘ from the stone it’s attached to, and in his case, it pulls about 2mm of stone with it.

No I doubt it is epoxy shrinkage causing the problem. High quality epoxy has little or no shrinkage.  It would have to be a very poor quality epoxy to be shrinking enough to do that.

The reason his epoxy is not working is that it is too rigid.  His existing rigid material has a “high modulus of elasticity”.  A material with “high modulus of elasticity” is a material that is stiff and/or rigid.  A “low modulus of elasticity” material is semi-flexible, and is not rigid or brittle.

Smaller pieces of the stone structure (in this case a tombstone) and pieces not in touch with the ground tend to get hotter and cooler faster than the larger pieces and pieces with ground contact. This is called “differential timing of the event”. For example the top of a tombstone can be heated and cooled on 5 sides, the top and the 4 sides. The base of the tombstone which is buried in the ground has earth or stone on all of its surfaces.  This earth and stone tends to keep the temperature of the base more stable by insulating it and slowing the change in temperature. This works much like the insulation in your house slows temperature changes inside your house.

When an object like a piece of stone is heated it expands (gets bigger).  When an object cools it contracts (gets smaller).  For example 100 feet of concrete will be 1 inch longer once it is heated 100 degrees F.  That is why expansion joints are cut into concrete.

In the case of tombstones all the pieces of the same type of stone have very similar if not identical “coefficient of expansion”. Since the pieces are positioned with potentially different timing of heating and cooling there is a “differential timing of the event” (see above). The result is stress areas you are seeing in the closest weakened plane in the stone near the bond line.

Product #2005  was specifically designed for tombstone (monuments) and/or stone bonding, or repair. Epoxy.com Product #2005 is very strong yet it is has a “low modulus of elasticity” (semi-flexible).  The low-modulus of elasticity helps to absorb differential movement (two sections of stone heating and cooling at different times), making it much less likely to cause a stress area in adjacent weakened planes.

Camouflage the bond line rubbing stone dust(ground off the original stone or a similar colored stone) into any exposed epoxy material while the epoxy is still “wet”. That way the dust will stick in the wet epoxy making the epoxy difficult to impossible to see.

Please send your additional question and blog ideas to norm@epoxy.com

 


Why Use Epoxy.com Products in “Green” Buildings?

August 20, 2012

110614_2044_EpoxyChipFl10.pngEpoxy.com’s 100% solid products (which are most of our product line) are included in many “Green” buildings. The logic for that is this:

1. Epoxy.com 100% solid products have  no VOCs. So you are reducing the carbon emissions.

2. Typical Epoxy.com 100% solid systems have done their job for decades, and there is no reason to believe they will not last for decades more. I personally have jobs that I installed with them that go back as much as a third of a century, that are not even starting to show signs that they will need replacement. That is the ultimate in reuse.

3. There is no need to recycle a product that can be reused for decades, but you can use recycled materials like glass aggregate in the epoxy matrix.

Epoxy.com encourages our customers to order material as they need it and to use all their materials before their expiration. That is why we do not require large stocking orders from new dealers, like most other companies. We want our customers to use up material they buy from us and not have any for it run out of shelf life. However, if Epoxy.com products do run out of shelf life, they are typically mixed and cured before disposal as is consitered in under most if not all local regulations as inert as common trash.

You can find more information about Epoxy.com Zero (0) VOC products at: https://www.epoxy.com/zero_voc.aspx

www.epoxy.com – Epoxy.com Home Page.

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Which is Better, Epoxy Injection or Urethane Injection?

August 15, 2012

Which is better, epoxy injection or urethane injection?  That is a little like asking which is better a 1/2 inch wrench or a 3/4 inch wrench.  The answer is whichever one is the Right Product for the Right Job.  This blog will explain this in more detail.

Epoxy injection should always be used in cracks where two sections were never meant to be separated.  For example a crack that took place in a piece of concrete that was intended to be monolithic (single pour), or where two sections of wood need to be bonded together. These repairs should always be by epoxy injection.

Urethane injection should always be used where the two separate members (pieces of structure) were never intended to be attached firmly but need to be waterproofed.   Consider for example, a sewer pipe and a basement wall (between a pipe and the concrete where it passes through the concrete).

Engineering determinations are required in places like a cold joint or the space between two sections of precast concrete.  If the structure is better off by the two members being bonded together, then epoxy injection should always be used.  If the structure is better off by the two members being able to have slight differential movement from each other and/or should never be bonded together, then urethane injection should always be used.

http://www.epoxy.com/injection.aspx

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