Page 16 - LWFC Catalog

Supplemental Specifications, Special Provisions, or listed in a Qualified
Product list or Approved Material. This presentation will compare and
contrast these specifications, where it is listed, the required physical
properties, and clear up some of the misconceptions about specifying
lightweight cellular concrete. It will review ASTM standards, approved
ACI documents, and accepted industry standards.

11AM - Evaluating the Corrosivity of Lightweight Fills Used in the
11:50AM Construction of Mechanically Stabilized Earth Retaining Walls
Wednesday Lightweight fills including expanded slate, expanded shale, expanded
clay and cellular concrete are often used as wall fill for construction of
October mechanically stabilized earth (MSE) retaining walls. MSE walls include
galvanized steel reinforcements that are buried within the wall fill and
20 provide structural resistance to the wall system. Demands for long-term
performance with anticipated service lives between 75- and 100-years
are such that the corrosivity of the fill material and the corresponding
metal losses of the reinforcements must be considered as part of
the design process. Parameters used to characterize the corrosivity
of natural soil or aggregates, and the corresponding tests used to
measure these properties, have been applied to assess the corrosivity
of lightweight fills. This includes measurements of resistivity, pH, chloride,
and sulfate ion contents, and comparisons with criteria established for
natural soils and aggregates. Lightweight fill consisting of expanded clay
was sampled and tested from an approach section supported with MSE
retaining walls in Myrtle Beach, SC. These samples did not meet current
criteria used to identity acceptable fills for MSE wall construction due
to high sulfate contents and low measurements of resistivity. The wall
system was instrumented for corrosion monitoring and observations of
corrosion rates were observed over a two-year period. The observed
corrosion rates were less than, or equal to, rates observed from other
sites where normal weight fills, that met current criteria for noncorrosive
MSE wall fills, were monitored in a similar fashion. These results suggests
that the same criteria that are applied to assess the corrosivity of normal
weight soils and aggregates may not be applicable to all materials
including lightweight fills, which may incorporate other factors inherent
to corrosivity. Laboratory testing has also been conducted on samples
of lightweight cellular concrete (LWCC). Measurements indicate that
the resistivity may be low depending on the moisture content of the
sample. Additional measurements of in situ conditions including moisture
contents of LWCC are planned as well as additional electrochemical
testing and observations of in-service corrosion rates. Results from
the proposed research will enhance our understanding about the
electrochemistry of LWCC, and the environmental conditions that may
exist within this material for mitigating corrosion of embedded steel
elements. It is very likely that factors that do not present themselves with
normal weight native soils or aggregates serve to mitigate corrosion of
metallic reinforcements in lightweight fills.

11AM - Performance of Cellular Concrete for Potential Engineering
11:50AM Material Arresting System (EMAS) Applications At airports without
a suitable runway safety area, Engineering Material Arresting System
(EMAS) is placed at the end of a runway to mitigate damage and
injuries resulting from an aircraft overrun. In EMAS, the tires of the