412-221-5141

Surface Tension is a measurement of the ability of a liquid to overcome its own internal friction and penetrate into a material like concrete. 10 Minute Concrete Mender™ has a surface tension three times less than water. It will penetrate concrete cracks and fissures quicker and deeper than water.

Please see Surface Tension testing data below.

University of Illinois at Urbana-Champaign

Department of                                                                                   telephone: (217) 333-4816

Civil Engineering                                                                                              facsimile: (217) 333-9464

                                                                                                email: dlange@uiuc.edu

September 16, 2002

Richard King

381 Bridgepoint Drive

South St. Paul, MN 55075

Dear Richard,

I am pleased to submit results of our measurement of surface tension of Concrete Mender conducted in accordance with our Wilhelmy Plate Method standard practice. Websites describing the Wilhelmy Plate Method for measuring surface tension include http://www.kibron.com/Science/ and http://www.tensiometry.com/STMethods.htm.

In our implementation of the test, we monitor the weight of a petri dish on an electronic scale as a glass slide is drawn up from a fluid in the petri dish.  The weight of the petri dish is reduced by the pulling force of the glass slide on the liquid surface.  The weight change is converted to surface tension by a simple equation.

The results of the tests are shown on the attached page. The surface tension of plain water, Concrete Mender Part A (lighter in color) and Part B (darker in color) are reported. Surface tension is reported in units of force/length (e.g. N/m). A summary of the surface tension of Concrete Mender and other reference fluids is shown below:

Concrete Mender Parts A and B separately and Parts A/B together soon after mixing exhibit surface tension similar to ethanol or benzene. The results also confirm that the Concrete Mender readily wets the concrete surfaces (i.e. the contact angle is 0°). These findings, along with the previously measured viscosity measurements of about 10 cPs, describe a fluid that has favorable wetting, sufficiently low viscosity, and sufficiently high surface tension to be readily drawn into the cracks and pore structure of concrete by capillary action in the first minute after contact. These physical properties of Concrete Mender are consistent with the observed penetration of Concrete Mender into concrete substrates, and are an important element of the ability of Concrete Mender to achieve superior bond with concrete repair surfaces.

Sincerely,

Prof. David A. Lange

Attachment: a) Lab data