054_065ACACHollywoodHighland
10/25/04
10:05 AM
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Concrete Material Sourcing
I
t’s important that concrete being supplied to a
project for a given paving type be consistent in
material source (cement and aggregates)
throughout the duration of the project. There
are several reasons why adjacent concrete pours differ in appearance:
• Change in cement type. Each type and brand has
subtle visual characteristics that will affect the
appearance of the finished slab should cement
brands vary during the construction of the project.
• Change in fine aggregate type, i.e. washed concrete
sand. There are a number of color variations in
sands available at concrete batch plants that will
affect the appearance of the finished product
(sandblast, acid and exposed aggregate finishes)
should the sand vary during the construction of
the project.
• Change in coarse aggregate type. Since coarse
aggregate rarely is visible on the surface of finished
architectural concrete paving, the control of this
source is not as critical. The exception is retarded
Dining terrace with cathedral and bell tower in background
display uniformity of integral concrete mix resulting from
strict adherence to specific mix designs that guarantee
sole source cement, sand, and aggregates.
or exposed aggregate.
• Change in mix design characteristics, including
slump, water/cement ratio, or admixtures, such as
accelerators or color pigments, will also affect the
appearance of the concrete slab.
• Use of different sourced materials often meets the
same performance and design strength criteria,
therefore a ready-mix batch plant may use and
batch several different sand, rock, and cement
sources in the course of one day. This is why it is
important to demand sole source materials on
each projects mix design and have a professional
check each delivery of ready-mix placed.
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