Page 11 - LWFC Catalog

PRESENTATION ABSTRACTS
PRESENTATION ABSTRACTS

fills, and backfilling of retaining walls, filling abandoned pipes, tanks and other voids, and
under slabs, although LCC materials have been identified by various implementing agencies
such as California Department of Transportation as one among the methods for ground
improvement, specifically due to its load reduction capability. Characterization of LCC
materials for geotechnical engineering applications have extensively been done in recent
years that will help the designers in identifying design parameters for specific applications.
This presentation includes extensive review of applications and properties of LCC materials
based on published literature and application practices in USA, specifically as a lightweight
fill material, and a recommendation for using LCC materials in geotechnical applications.

2PM - Geotechnical Applications for Expanded Shale, Clay, and Slate Lightweight Aggregate
2:50 PM Slopes, embankments, and retaining wall structures for infrastructure projects are frequently
constructed on sites with less than ideal soil conditions. When unsuitable soils are encountered
the goal of the geotechnical engineer is to provide cost-effective solutions to remedy issues
related to settlement, stability, and bearing capacity. When these concerns are present, it
can be desirable to use fill materials with low densities in order to reduce the magnitude of
the applied loads. Otherwise, the use of conventional or quarried select fill materials may
require more costly ground modification techniques to achieve a suitable factor of safety. This
presentation will explore the use of expanded shale, clay, and slate lightweight aggregates
as a cost effective solution on sites with challenging soil conditions. The content of the
presentation will include a general overview of common ground improvement methods and
where lightweight aggregate fill options fit. Specific applications will be reviewed along with
select project case histories.

2PM - Discussion of Two Large Design Builds in California Lightweight cellular concrete was
2:50 PM successfully used in construction of embankments and retaining wall structures for the last two
major Design-Build project in California, that include the Gerald Desmond Bridge Replacement
in Long Beach, California and the I-405 Improvement Project from SR-73 to I-605 in the County
of Orange, California. This talk looks to share lessons learned as a geotechnical lead that
oversaw the design of eight LCC walls with precast panels and reinforcement and four semi-
gravity walls with LCC backfill that required the collaboration of California Department of
Transportation (Caltrans) to approve. The geotechnical challenges for these projects that
required the use of LCC included large seismic loading, shallow groundwater, compressible
material, reduced soil strength due to liquefaction and lateral spreading. No standardized
basis of design is available for design of LCC walls. Whereas semi-gravity walls with LCC backfill
can be designed based on conventional methods prescribed by AASHTO, walls similar to
MSEs with LCC fill, referenced here as LCC with precast panels and reinforcement, have no
established design approach that results in debate of the internal and external behavior. I
will share our design approach that bounded the problem to provide for uncertainty and
discuss the pitfalls of splitting external and internal design of LCC walls with precast panels
with reinforcement. We will discuss the merits of waterproofing or not waterproofing and
associated lateral pressure associated with design. This presentation will provide insight into
acceptable practice on projects that require Caltrans oversight.