Masonry Magazine January 2005 Page. 25
During the NCMA evaluation of Mason Bond, tests showed the adhesive with filler achieved an average modulus of rupture at 345psi, while the adhesive without filler (pictured here) achieved 372 psi. For a similar wall type with S type mortar, the modulus of rupture is 63 psl.
ITW TACC, A PRODUCER OF HIGH-PERFORMANCE ADHESIVES
ITW TACC, a producer of high-performance adhesives for professional and industrial use, has developed Mason Bond, a new adhesive product that has the potential to replace mortar in concrete block, brick and retaining wall construction. The company states that walls built with Mason Bond will be five times stronger than walls built with mortar, and because of the ease of application the product has the potential to double worker productivity.
The National Concrete Masonry Association (NCMA) evaluated Mason Bond and conducted wall flexure testing in accordance with ASTM E 72-95, "Standard Test Methods of Conducting Strength Tests of Panels for Building Construction." The report issued in March 2004 concludes, "Tests here showed the adhesive achieved an average modulus of rupture of 349 psi," and "this is 5.5 to 5.9 times the bond strength required from the code."
Tim Walsh, ITW TACC Business Manager, was at the NCMA facilities when they conducted the tests. "Before we did the testing at NCMA, we did some small-scale lab testing and felt our product would be stronger than mortar, but I believe we surprised the people at NCMA with the final results," Walsh says. "We used lightweight smooth faced CMUs for the construction, and when the walls finally broke we had areas of block failure instead of bond failure. I don't think they had seen that type of failure in wall flexure testing before."
According to Walsh, the most significant advantage of the product is the potential to reduce labor costs by increasing productivity. "Mason Bond does not require mixing at the job site like conventional mortar, and it is applied as a bead using caulk tubes or a pumping system ITW TACC has developed for larger applications," Walsh says. "We have had several block manufacturers and masonry contractors evaluate the product, and they believe that using this product may double workers' productivity during wall construction. A Detroit area contractor built a few walls for evaluation, and he stated construction time was reduced by 65%."
Depending on the region of the country, labor costs generally account for a minimum of 60% of the installed cost of a CMU. Use of Mason Bond would reduce the installed cost by 30%, giving contractors a chance to improve profitability or to offer lower-cost construction and provide a competitive advantage over tilt-up concrete and poured in place concrete construction.
In addition, potential labor savings can be achieved due to the ability to use the product in different weather conditions. The use of mortar in hot (above 90 degrees F) or cold (below 40 degrees F) conditions has provisions that have extra requirements adding cost to construction. Construction with wet CMU is restricted because bond strength between CMU and mortar is reduced, which can result in construction delays. ITW TACC has performed testing in a variety of weather conditions using wet and dry blocks. Results indicate that those weather conditions did not appear to have an impact on bond strength.
Dr. Richard Bennett, Professor of Civil Engineering at the University of Tennessee, has reviewed the report and believes there is a lot of potential for the product. "It seems to have both economical benefits and structural benefits. I think it has great potential to transform how masonry is constructed," Bennett says.
January 2005
Masonry 23
Photo courtesy of ITWK