Advanced Concrete Technology Testing and Quality

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Advanced Concrete Technology Testing and Quality


The analysis of fresh concrete comprises a range of on-site tests which can be carried out
to determine the cement, pulverized-fuel ash (pfa), ground granulated blast furnace slag
(ggbs), and water content of the original concrete mix, and the aggregate grading. Very
fine additions to the concrete such as microsilica are treated as part of the fines content
of the mix.
The main advantage of fresh analysis is that it gives the concrete technologist a set of
tests which can be performed on-site, as the concrete is being placed. As part of a quality
control scheme, testing at regular intervals will provide a guide to the variability of the
concrete as supplied to, or mixed, on-site. Using a rapid analysis machine (RAM), the
operator is able to determine the cement content within 15 minutes of taking the samples.
The times taken for other test methods .

The main disadvantage of fresh analysis is that all the tests are based on the physical
separation of the cement, pfa and ggbs from the other constituents of the concrete, and an
allowance has to be made for the fines or silt content of the aggregate. Calibration
procedures using site materials and regular checks on silt content of the aggregate can
reduce this problem to an acceptable level. The initial cost of the equipment would
prohibit its use on small sites, but Clear (1988) has shown that if the concrete samples are
stored below the temperature at which hydration ceases, then they can be transported in
a cold box to a test house for analysis using any of the techniques described in this
chapter.

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