Fairbanks 12-1492 - 12-1496 A.A.R. Combination Railroad Track/MTS - Manual (Page 58)

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The slump test is a direct measure of the amount of water in the mixture, unless ADMIX-
TURES are added. Admixtures are liquid chemicals added to concrete to make it easier to
place without the reduction in strength adding water would cause. Admixtures of this type are
known as "plasticizers" or "water reducers", and adding them to the mixture will either make
the concrete mix more "plastic" with the same amount of water, or allow the concrete to have
the same "plasticity" with a smaller amount of water (increasing strength). Testing and ensur-
ing the slump specification for concrete is correct will enable the concrete mixture to have the
strength and placability the designer requires it to have.
APPENDIX VIII: About the AAR:
The American Association of Railroads (AAR) is one of the nation's oldest and most respect-
ed trade associations and represents the major freight railroads in the United States, Canada
and Mexico. Amtrak and some commuter railroads are also members of the AAR. In addition,
the AAR has two categories of associate members, one for smaller railroads and a second for
railway suppliers and others with an interest in railroads. The AAR serves as the joint repre-
sentative of its individual members in matters requiring cooperative handling to better enable
railroads to be an efficient, safe, inter-linked system. It is governed by a board of directors
that includes the CEO of each Class I railroad in the United States. Amtrak, smaller railroads,
Mexican railroads and the Railway Association of Canada are also represented on the AAR
Board. One CEO serves as AAR Chairman for a one-year term which rotates among the
Class I railroads.
About AREMA
The American Railway Engineering and Maintenance-of-Way Association (AREMA) was
formed on October 1, 1997, as the result of a merger of three engineering support associa-
tions, namely the American Railway Bridge and Building Association, the American Railway
Engineering Association and the Roadmasters and Maintenance of Way Association, along
with functions of the Communications and Signal Division of the Association of American
Railroads.
The rich history of the predecessor organizations, each having over 100 years of service to
the rail industry, is the legacy of AREMA.
About the American Railway Engineering Association
At the suggestion of Railway Age magazine, a meeting was held in Chicago on October 21,
1898, to organize a forum for the development and study of recommended practices for the
newly-integrated standard-gauge North American railway network. This led to a meeting in
1899 in Buffalo, New York, to adopt a constitution and establish a permanent organization
named the American Railway Engineering Association (AREA). From its inception, the AREA
dealt with the many engineering challenges through standing technical committees. Five of
those committees; ties, rail, track, buildings and yards & terminals continued intact continu-
ously from 1899 until the merger and still continue under AREMA functional groups. In 1905,
AREA issued its first Manual of Recommended Practices. Its name was changed to the
Manual of Railway Engineering in 1970 and is updated annually by the technical committees.
The manual, which is now also available on CD-ROM, will continue under AREMA.