Page 11 - LWFC Catalog

PRESENTATION ABSTRACTS
PRESENTATION ABSTRACTS

function that the lightweight fill will serve and then calculating the required numerical value of
a property for that function.

2PM - State of the Practice for Application of Lightweight Cellular Concrete in Geotechnical
2:50 PM Engineering Lightweight cellular concrete (LCC) also known as Low Density Cellular Concrete
or foam concrete or grout has been economically used for various engineering applications
such as below grade fill and embankment fill. LCC is defined as concrete made with hydraulic
cement, water, and preformed foam to form a hardened material having a oven-dry density of
50 pcf (800 kg/m3) or less. Although lightweight cellular concrete has been applied in various
engineering projects since almost a century ago, extensive use of LCC in civil, geotechnical
or construction engineering projects has only been observed in the past few decades. There
are very limited published design guidelines available on LCC applications such as engineered
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 - Lightweight Fill in Two Major Design-Builds in Southern California. Lightweight cellular
2:50 PM concrete was 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.