A Self-Learning Manual - Institution of Engineers Mauritius

A Self-Learning Manual
Mastering Different Fields of Civil Engineering Works (VC-Q&A Method) Vincent T. H. CHU
surface of the grout during the initial stage of cement hydration process.
Later on, some of the floating water is re-absorbed into the grout due to
further hydration reactions. Even without the problem of bleeding, there is a
total reduction of volume of grout after hydration action when compared
with the total initial individual volume of cement and reacted water.
Bleeding tests should be carried out for grout because of the following
reasons [22]:
(i) During bleeding, the upflow of water from grout mixture leads to the
formation of channel paths inside the grout mix. These channels act as
potential paths for aggressive materials to pass through as these
channels would not be closed during further hydration of the grout.
(ii) The loss in volume by bleeding generates voids inside the grout mix
which affects the properties and performance of the grout. Moreover, it
increases the chance of corrosion of steel elements protected by the
grout. (e.g. tendons)
(iii) In bleeding test, there is a usual requirement of total re-absorption of
water after 24 hours of grout mixing because for some cold countries,
this layer of water may cause severe freezing problem leading to frost
damage.
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