Building with Concrete Home

May 19, 2000

Mutual Materials buffs up ‘building blocks’

Bellevue firm out to prove concrete’s environmental merit

By LISA LANNIGAN
Journal staff reporter

Mutual Materials of Bellevue is out to change the way the Northwest thinks about concrete - it isn’t just flat and gray anymore.

With 10 plants throughout the Northwest, the newest recently opened in Lacey, Mutual Materials creates not only bricks but also concrete modular units (CMUs) and pavers for all types of construction. The results are anything but drab.

Unlike concrete poured into place on-site, Mutual Materials makes products with machines which pour, cure and strengthen the modular units. Large concrete blocks can be used in vertical applications, while pavers can be used in streets and pathways.

"There’s really been an increased use in pavers," said Joe Bowen, vice president of Mutual Materials. "The market is growing rather steadily."

While CMUs are catching on in larger projects, Bowen says many owners of residential project are reluctant to use concrete. But concrete can be creative. Colors can be applied, and aggregates can be added to give the CMUs color and texture.

More homeowners and landscapers are turning to colored concrete pavers to create paths and retaining walls. A retaining wall of CMUs can be constructed over time and the units moved around easily. "We can use modular units in very difficult or demanding situations," Bowen said. "It’s easy for people to work with."

‘ We can use modular units in very difficult or demanding situations. It’s easy for people to work with.’ - Joe Bowen, vice president Mutual Materials

On the civic side, one reoccurring problem with both poured concrete and pavers is the resulting stormwater runoff. As rain hits the hard, impervious surface, the water runs to the side of the pavement rather than seeping into the ground. The result is an undesired flow of water carrying roadway contaminants to the nearest creek.

One solution manufactured and marketed by Mutual Materials is the UNI Eco-Stone, a system of interlocking permeable concrete pavers. Designed with a 8,000 psi to be used in roadways and intersections, these octagon-shaped pavers contain 1- to 2-inch gaps that allow water to flow through the surface and into the ground. "Water is going to find its way into the void," Bowen said.

Eco-Stone pavers are installed like regular pavers. The units are placed in sand on a prepared site, either by hand or by machine. A special aggregate material is then swept into the gaps. This works to "lock" the pavers in place while allowing water to flow through the gaps.

"(It’s) the same principle for concrete pavers. The only difference is the provision for a void," Bowen said. The rate at which water will flow through the surface depends on the materials used to fill the voids and the slope of the pavement. "Eco-Stone depends on the right kind of aggregates being used."

The ground quality also impacts the effectiveness of the Eco-Stone units to draw away rain water. A permeable subgrade will allow the water to pass through and travel down to the water table. In other situations, a drainage pipe can be installed under the surface to carry water away. "The benefit of this system is you can use part of the pavement system for your storage requirements for stormwater," Bowen said. "This is a new approach."

Another advantage of using pavers in a roadway is that, unlike asphalt or poured concrete, individual pavers can be removed for subsurface utility work and be easily replaced. "You can pull out the units that you need to pull out," Bowen said. "You don’t need to re-pour."

Using pavers or CMUs can cost more than pouring concrete. "In many applications, the initial cost is higher, but over the life of the paving system, the cost can actually be lower," in terms of maintenance and upkeep, Bowen said. A walkway can be $5 to $6 a square foot, while large applications cost considerably less, he said.

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