Epoxy Resin Strengths Explained
Compressive, Tensile, Flexural, and Bond Strengths of
What do the Strength Numbers for Epoxy Mean?
There are 4 primary strengths that are very important for most civil and
mechanical engineering applications of epoxy: compressive strength, tensile strength, flexural strength, and bond strength.
The test methods used to get the specific strength of the epoxy is done by the
ASTM testing method listed on the epoxies technical data sheet. The master test
standard for epoxy is ASTM C881. Norm Lambert the author of this page is a
voting member of ASTM Technical Subcommittee
C09.25 that sets the
ASTM C881 standard.
Compressive Strength of Epoxy
This strength is the ability of the material to handle weight. Compressive
strength tests are ran by pushing both sides of a cylinder of the epoxy (or
concrete etc.) on the top and bottom of the cylinder. Typical numbers most
non-flexible epoxies start at slightly under 10,000 psi (pounds per square inch)
and work their way up from that. To put this into perspective typically quality
concrete has a compressive strength of about 3,000 psi. Very high end concrete
can have compressive strength of about 5,000 psi but concrete at that high a
strength is not typical. Most concrete is 3,000 psi plus or minus.
Some people think that the higher the tensile strength the "better" the material. That is not necessarily true. As some epoxies get to very high compressive strength the may become
brittle. If a product is brittle it can still break easily. That is because flexural strength has been
compromised for the sake of getting a higher compressive strength number. More on this under tensile
Epoxy.com Products are formulated to balance all the various strengths needed for a specific application. For example if you are installing an Epoxy.com Product over concrete, there is no need for the epoxy to have a compressive
strength of more than a couple times more than the concrete. That gives you a high
safety margin so that if there is a high compressive load the concrete will fail before the epoxy. Once the concrete has failed the epoxy is just along for the ride.
Interestingly enough in the real world materials don't really fail in compressive, they typically break on the side opposite the side of the load first, which means it actually fails in tension.
Tensile Strength of Epoxy
The Tensile of epoxy is basically the load in just the opposite direction of compressive strength. As you remember compressive strength tests are ran by pushing both sides of a cylinder of the epoxy or other material. Tensile
strength is tested by pulling on the top and the bottom of the cylinders.
Materials do not break in compression, they break in tension. Prove this to yourself. Take a tooth pick or some material that you can bend in your hands until it breaks. It does not break on the side you are pushing on (the
compressive side) first. It brakes on the side you are pushing towards first. The side that is in tension
is the side you are pushing to.
That makes the tensile strength the most important one to consider when
In the case of concrete the compressive strength normally tests out at
about 10% of the compressive strength. So concrete with 3,000 lb.
compressive strength typically only has about 300 lbs. of tensile strength.
By comparison Epoxy.com epoxy has a much higher tensile strength verses
compressive strength. By comparison Epoxy.com Product #10
Epoxy Mortar has a compressive strength of 10,000 PSI (about 3 times that of
standard concrete) but Product #10 Epoxy Mortar has a tensile strength
of 3,500 psi (at least 10 time stronger than concrete). So since materials
break in tension first Epoxy.com Product #10 Epoxy mortar and most Epoxy.com
Products are 10 times higher
than standard concrete.
Flexural Strength is measured by supporting a bar of the epoxy or other material on both ends and then applying a load in the middle. Compressive strength and tensile strengths are measured differently, but in epoxy they really are talking about the same thing. These two tests measure the ability of the epoxy to resist being pulled apart.
This test is much like what you are doing when you bend the toothpick in your
hands, like we discussed earlier
Bond strength is the measurement of how well an epoxy bonds to the
substrate. Epoxy.com resins are designed to have a bond strength on
concrete that is greater than the tensile strength of the concrete. If
the bond strength of the epoxy or epoxy like material is greater than the
tensile strength of concrete than if there is a failure it will be a failure
of the limits of the strength of the concrete not the epoxy. Epoxy bond
strength is typically measured under ASTM D-882. Bond strength to concrete
is measured under an American Concrete Institute test method "Adhesion to
Concrete ACI Committee 403".
Cite: References Used on this Page
ACI Guide for Use of
Epoxy Compounds with Concrete: "Adhesion to
Concrete ACI Committee 403"
ASTM C109 / C109M
- Standard Test Method for Compressive Strength Concrete
ASTM C881 / C881M -
Standard Specification for Epoxy Resin Base Bonding Systems for Concrete
C882 Test Method
for Bond Strength of Epoxy-Resin Systems By Slant Shear
D638 Test Method
for Tensile Properties
D695 Test Method
for Compressive Properties
Proper mixing and installation is critical to the optimal success
of all product. See
MSDS for more details on our products.
Be sure to contact us with any questions and/or concerns that you
For more information please contact:
A Division of Epoxy Systems, Inc
20774 W. Pennsylvania Ave.
Dunnellon, Florida 34431
Florida & Vermont
Office Hours: 9AM-4PM Eastern Time (6AM-1PM Pacific Time).
Closed 12Noon-1PM Eastern Time for Lunch
321-206-1833 Customer Service - Ordering and Order Status
Katey Fontaine, VP - Customer Service Director
352-533-2167 Norm Lambert, President - Technical Support Director
352-489-1666 Accounting and Administration
Debby Lambert, CEO, and CFO
352-489-1625 Fax line to all Departments
24 hour Hazmat Emergency Telephone Response Service -1-800-633-8253
|| We accept MasterCard, Visa, American Express, Discover,
or Wire Transfers.|
Copyright © 1994-2013 EPOXY.COM
a division of Epoxy Systems, Inc. -
Florida and Vermont. All rights reserved.
other wise agreed upon in writing, buyer is responsible for the cost of
information is presented in good faith to assist in determining whether this
product is suitable for application. No warranty or representation, however, is
intended or made, nor is protection from any law or patent to be inferred, and
all patent rights reserved.
division of Epoxy Systems, Inc. warrants its products (when
properly stored) for the period of time as follows: Epoxies, Product
#315, Product #315BC, and Product #316 one (1) year; Polyesters,
Methyl Methacrylates (normal) two (2) months and Polyurethanes Four (4) months;
Power Tools and Equipment 90 days; Vinyl Esters, and all other
resins (not specifically mentioned above) 30 days; hand tools
(non-power tools) 30 days. Epoxy.com warrants that its
products will be free of manufacturing defects and will be in
conformity with published specifications when handled, stored, mixed
and applied in accordance with recommendations of Epoxy.com. If any
product fails to meet this warranty, the liability of Epoxy.com will
be limited to replacement of any non-conforming material if notice
of such non-conformity is given to Epoxy.com within the warranty
period for the material (as indicated above), or within 1 year of
the delivery of materials (whichever is sooner). Epoxy.com may in
its discretion refund the price received by Epoxy.com in lieu of
replacing the material. No customer, distributor, or representative
of Epoxy.com is authorized to change or modify the published
specifications of this warranty in any way. No one is authorized to
make oral warranties on behalf of Epoxy.com. In order to obtain
replacement or refund the customer must provide written notice
containing full details of the non-conformity. Epoxy.com reserves
the right to inspect the non-conforming material prior to
replacement. EXCEPT FOR THE EXPRESSED WARRANTY STATED ABOVE, THERE
ARE NO OTHER WARRANTIES, EXPRESSED OR IMPLIED, INCLUDING WITHOUT
LIMITATION, ANY IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR
PURPOSE. Epoxy.com 'S OBLIGATION SHALL NOT EXTEND BEYOND THE
OBLIGATIONS EXPRESSLY UNDERTAKEN ABOVE AND Epoxy.com SHALL
HAVE NO LIABILITY OR RESPONSIBILITY TO THE PURCHASER OR ANY THIRD
PARTY FOR ANY LOSS, COST, EXPENSE, DAMAGE OR LIABILITY, WHETHER
DIRECT OR INDIRECT, OR FOR INCIDENTAL OR CONSEQUENTIAL DAMAGES. All
quotes and sales subject to availability.
Many of our
products are made on an individual order basis. Unless
authorized in writing by Epoxy.com a division of Epoxy Systems, Inc.
in writing before the material is made, there are no returns on
items purchased from us, once the order has been processed, and the
material made. In the event of authorized returns a restocking
charge will be charged in the amount of 30% of the value of the
material returned or $150 whichever is greater. No returns on
non-list priced items. All Returns are for merchandise (store)
credit only, no cash or credit card credits. In the event of a
return, buyer is responsible for the cost of shipping and handling
in both directions.
[Catalog of Products]
[Where to Start]
[Elastomeric Polyurethane Systems]
[Epoxy Resin Systems]
[Seamless Garage Floors]
[High Temperature Epoxy]
[Joint Systems / Sealants]
[Methyl Methacrylate (MMA)]
[Mortars / Grouts]
[Novolac Epoxy] [Primers Sealers]
[Who We Are]
[Tech Data Sheets in Acrobat Format]
[MSDS in Acrobat Format]
[Online Ordering Authorization Form]
[Add this page to Favorites]