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  • Concrete Expert Witness

Concrete Expert Knowledge is Premium

The following excerpt is from an Expert Opinion's Declaration. This excerpt in particular exemplifies the level of knowledge and experience required to provide expertise.

This excerpt describes specific types of defects in a concrete warehouse slab.

"The pop-outs are due to “alkali-silica reaction” or ASR. The concrete contains “reactive aggregates” commonly identified as Opaline shales from the geological unit known as the “Monterey Formation.” The Monterey Formation is characterized by Opaline shales as the primary contributor of reactive components which lead to popouts. (Cherts are also present but much less reactive in alkalies.) The Monterey Formation is present in the state of California along the coast and coastal ranges from northern Orange County to Monterey. These aggregates are typical of the sort of aggregates that pose on-going problems in the North Los Angeles County, Ventura County, Santa Barbara County and San Luis Obispo County areas. Well known conditions which aggravate ASR are exposure to water, especially those containing alkalies. This condition is mitigated by judicial and informed use of concrete making ingredient materials, like supplemental cementing materials, applying appropriate code provisions, and using good judgement. Collectively, these failures are defects in the standards of good workmanship and acceptability of materials, durability, and serviceability and in warrantee work provided by Oltmans’ Construction, as follows. The source of the concrete aggregates in this project is the Vulcan Sun Valley plant, with a production source generally describes as the alluvial fan material whose source is the Big Tajunga Wash. Given the nature of the source, the setting of the geologic units and the way the alluvial material came into existence, especially in recent geologic times, it is fully expected that some of the materials excavated from the various Vulcan pits tests as Innocuous, while other times it ranges in degrees of reactivity from Potentially Deleterious to Deleterious, with the tendency toward creating popouts. Popouts are the very most common manifestation of ASR in Monterey Formation materials, especially on this southern end of the Formation. They are the direct result of the relative abundance of Opaline shale materials concentrated on discrete and dispersed particles whose presence is known and whose frequency of occurrence is irregular."

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