Masonry Magazine July 2002 Page. 19
The Engineered Wood Specialists!
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Constructed from lightweight durable aluminum, it features a swivel head for easy use in difficult areas and comers. It has a durable 6-foot powder coated handle. The scraper uses a standard 7" rubbing disc as an abrasive pad. The disc holder is engineered for quick and easy disc changes. FOR MORE INFORMATION CONTACT: SLIP INDUSTRIES, 115 W. STIEGEL ST, MANHEIM, PA 17545 1-800-722-8339-1-717-665-2139 FAX 1-877-722-8339 WEBSITE: www.slipindustries.com The Voice of the Mason Contractor July 2002 Masonry 17
ods they are used to using. "Getting that first course level is going to be a little bit different than what the mason contractor is used to where even if his leveling pad isn't perfectly level he has the ability to use some of his mortar, his bedding material, to level off the block. In segmental retaining walls mortar is not used, they're dry stacked, so some of those inconsistencies are caught up through shims, small pieces of material placed between blocks as they go up. The block producers and system licensors recommend different materials for their products and what to use as shims."
Instead of a pored concrete pad, the leveling pad for an SRW is often gravel. "An SRW is placed on a compacted gravel bed that's generally 6 to 8 inches in thickness and about 6 inches wider on each side than the depth of the block. So if it's a 12-inch deep unit, they make a 24-inch pad," says Carter. In lieu of gravel, the contractor can elect to place a 6-inch minimum thick unreinforced concrete leveling pad (3,000 psi concrete). Contractors often have different opinions as to which material, concrete or gravel, expedites construction, but both are exceptable materials.
SRWs are generally installed with a slight setback between units, creating a batter into the soil behind the wall. The wall batter compensates for any minor lateral movement of the block face due to earth pressures. This prevents the wall from appearing to rotate. Conventional SRWs will often incorporate increased wall batter to improve wall system stability.
Increasing the unit width or weight provides greater stability, larger frictional resistance, and larger resisting moments because the stability of the system depends primarily on the mass and shear capacity of the SRW units. All SRW units provide a means of transferring lateral forces from one course to the next. Shear capacity provides lateral stability in mortarless systems such as these. The methods used to create shear capacity include shear pins or keys, leading lips, trailing lips, clips, pins or compacted columns of aggregate in open cores of the blocks.
Soil-reinforced SRW Soil-reinforced retaining walls are composite systems consisting of SRW units combined with a mass of retained soil, integrated with the wall by horizontal layers of reinforcement, typically a geosynthetic material (see glossary). This reinforcement increases the effective width and weight of the gravity mass,