The American Pressure Grouting & Mudjacking Association and Black-Jack Grout Pumps Inc. recommend the following material for use in any Slab-Jacking or Concrete Lifting application with consideration to:
Cost (material & equipment) Compression Strengths Flow under pressure Availability State and Federally Accepted Recyclable
CEMENTITIOUS GROUT is by far the most user friendly and versatile grouting material. (Portland Cement, Fly-Ash, Sand, water, Bentonite & admixtures as required)
The cost of the polyurethane equipment and materials are approximately 4 to 5 time the cost of conventional grouting equipment and materials. Compression strengths are easily controlled by adding or subtracting Portland cement to grout. Average compression strengths of polyurethane are 80-100 psi, while average compression strengths of Portland cement, Fly-Ash, and Sand are 1,500-4,000 psi. Higher compression strengths are critical for heavy bearing loads. Slab deflection has been observed when using lower strength materials. Flow of material under pressure is close to equal; both polyurethane and the above grout mix have extremely high lubricity therefore penetrating the smallest area. Portland cement, Fly-Ash, Sand, and Grout can be purchased and delivered by most any ready- mix company in bulk/bagged or mixed. Distributor availability of polyurethane is limited when compared to ready-mix companies. Grout costs average between $96.00-$128.00 per cubic yard(prices are subject to change). Portland cement/fly-ash/sand grout has been accepted and used by State and Federal agencies. At present polyurethane has been used as well; however municipalities within the study area indicated polyurethane to be cost prohibitive. In the state of Missouri on highway 54 near Mexico, polyurethane was injected and resettling occurred after a short period of time. At present most State and Federal Department of Transportation recycle Portland cement pavement, polyurethane being a non-cementious material, separation will increase cost of the re-cycling processing. End results of any material used for Slab-Jacking is completely dependent on the supporting materials of the Portland cement pavement, however both polyurethane and grout can be injected into soil, peat moss, aggregates (when applicable) for stabilization.
Page 2 of 3
August 17, 2010