WestCon Tribune

January Review

Structural Shotcrete

And Below Grade Waterproofing Systems

Presented By: Brad Miller

Southwest Regional Manager, CETCO

 

Westcon would like to thank Brad Miller, CETCOÕs Southwest Regional Manager for taking the time to give a thorough presentation on Shotcrete.

Mr. Miller identified the effects that structural shotcrete uses for below grade foundation walls on blind side waterproofing systems such as bentonite waterproofing systems. He discussed both hydrostatic and non-hydrostatic waterproofing systems.

Hydrostatic conditions exist when elevation of the below-grade foundation is lower than the project site ground water level or historical high water table. Hydrostatic conditions are typically continual but may be intermittent with the fluctuation of the natural ground water table.

Non-hydrostatic conditions exist when site soil testing has determined that no ground water table exists or the elevation of the below-grade foundation is well above the expected historical high water table elevation. Intermediate hydrostatic pressure conditions may exist after precipitation or irrigation but is not a continual or prolonged condition,

A national design and installation approach has been developed using a warranted bentonite waterproofing system.

Voltex DS is a highly effective waterproofing membrane comprised of 1.10 pounds of Volclay sodium bentonite per square foot, two polypropylene geotextiles, and an integral HDPE geomembrane are bonded to the outside surface of the non-woven geotextile. The two geotextiles are interlocked by a proprietary needlepunching process which encapsulates and confines the sodium bentonite. The HDPE liner provides extremely low permeability for water vapor and gas transmission.

Volclay sodium bentonite is a non-toxic mineral of volcanic origin that expands and seals upon hydration with water. Volclay bentonite stops water by forming a dense monolithic membrane on the exterior of the structure that is impervious to water.

Voltex DS is used for waterproofing below-grade horizontal and vertical surfaces. Typical applications are underslab and property line construction, including soldier pile and lagging, metal sheet piling, and concrete caisson retaining walls.

Installation of Voltex DS requires positioning the product and fastening it into place. It can be installed on green concrete, in virtually any weather, without the need for primers or adhesives. It can also be cut on site to form around corners and penetrations.

Mr, Miller provided a detailed manual summarizing the design and installation approach which was handed out at the presentation.