“You're combining 25-micron material with 15-micron material,” Grasso says. “You are getting better adhesion to the surface area of the aggregates.
“In a test to create a 6000-pound compressive design mix, we put a 20 percent supplement Pozzotive into the matrix, and we tested at 8000 pounds,” he says. “That is with a lightweight aggregrate, which is known for being weak. But because you're getting such good surface coverage, it creates a much stronger matrix.”
The white pozzolon is ideal for manufacturing white CMU and takes advantage of high solar reflectivity, or albedo effect.
Pozzotive block and brick meet requirements of ASTM C-90, Standard Specification for Loadbearing Concrete Masonry Units; ASTM C-129, Standard Specification for Nonloadbearing Concrete Masonry Units; and ASTM C-1634, Standard Specification for Concrete Facing Brick.Spreading the word
Empire Resources Recovery of New Rochelle, N.Y., Jonathan Rose Cos. owns the intellectual property rights to Pozzotive. The material is manufactured by Urban Mining Northeast, also of New Rochelle. Kingston Block & Masonry Supply is an authorized manufacturer of Pozzotive block and brick serving metropolitan New York City. “We're setting up a protocol so everyone works with the product in a responsible way,” Grasso says. “The entire country is open.”
He talks favorably of other uses for Pozzotive, such as ready-mix concrete (see sidebar on page 20) and precast concrete plank. Concrete plank and high-strength concrete block are very affordable and effective materials for building dormitories, affordable housing, barracks, and jails. “It's a showcase for recycling,” Grasso says.
One such showcase project is supplying the glass feed-stock. The United Nations building in Manhattan is receiving a new skin. Sixty tons of glass which is being removed will be processed and manufactured into Pozzotive.
For more information on the companies in this article, visit Kingston Block & Masonry Supply atwww.kingstonblock.com,Empire Resource Recovery atwww.empireresourcerecovery.com,and Urban Mining Northeast atwww.urbanminingne.com.
Ready-mix Producer Promotes Pozzotive
William Stanley, vice president, materials division at O&G Industries, is a strong supporter of using Pozzotive as a cement substitute for ready-mixed concrete.
O&G's concrete division, based in Torrington, Conn., has been using the material at its six plants for a year and a half. The producer speaks favorably of its improved strengths and neutral set times. “There is a great deal of interest in it because it is a post-consumer recyclable supplementary cementitious material,” Stanley says.
Pozzotive's particle size and distribution aids in adding strength to ready-mix. “This runs about 12 microns in size, while Type 3 cement is around 25,” he says. “At 12 microns, you are approaching the size of microsilica.
“With a six-sack mix, what we normally use for 3500 psi, and with 15 percent replacement with Pozzotive, we're getting 4500 psi in 28 days and 5500 psi in 56 days. That's about 1000 more than we would get with a six-sack mix.”
The producer has been promoting its use in ready-mixed concrete to architects, and it has been specified in new school buildings in Connecticut. All new school buildings in the state are required to be designated at least LEED Silver.