THE EFFECT OF MIXING SEQUENCE ON THE PROPERTIES OF CONCRETE
THE EFFECT OF MIXING SEQUENCE ON THE PROPERTIES OF CONCRETE
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Date
2017-06
Authors
IBRAHIM, Zahradeen Wala
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Abstract
Concrete is the most demanded material only second to water as a substance, with this, it
can only be imagined that huge expense and resources have been put into it. In
consideration with the aforementioned fact on concretes‟ demands coming in tune with
the advancements of the 21st century production researches, cost free methods are being
optimized to boost production efficiency. This research entitled “The effect of mixing
sequence on the properties of concrete” is about the latter statement, as it deals directly
with finding the most suitable mixing sequence to optimize production efficiency without
any added resources. The research focused on the fresh and hardened properties of
concrete. British Research Establishment (BRE) Method of mix design was used. A total
of 720 cubes were cast for tests at the following ages of 7, 14, 28 and 56 days. Twenty
four (24) mixing sequences were assessed. Among the mixing sequences, two
standardized mixing sequences from the ASTM and ACI were chosen. It was found that
samples mixed using the standard mixing sequences of the ASTM and ACI passed all the
standard requirements for all properties of concrete assessed. However the samples
produced using ACI mixing sequence had better hardened concrete properties when
compared with the samples of concrete made using ASTM mixing sequence. All the
concrete batch samples from the various mixing sequences passed the standard conditions
for compacting factor and plastic density. Samples mixed using mixing sequences (22, 19
and 17) did not pass the standard condition for slump. Samples mixed using mixing
sequences (14 and 17) did not pass the standard condition for air content. Samples from
mixing sequence 24 had optimum compressive strengths of 23.40N/mm2
, 25.52 N/mm
2
,
30.84 N/mm
2
and 35.56 N/mm
2
for 7, 14, 28 and 56 days of testing respectively andpassed all the standard conditions for all properties tested. It surpassed samples from the
standardized mixing sequences in grade by at least 4.7% for every test age. During
concrete production, with all processes, materials and proportioning considered, two sets
of concrete samples from two different mixing sequences can differ in average from
0.91% to 41.85% under water absorption while two sets of concrete samples from two
different mixing sequences can differ in average from 0% to 100% under abrasion
resistance. From the properties of concrete tested, the various mixing sequences used
have the most positive effects on plastic density followed by air content then slump and
finally compressive strength. Due to the differences in the properties of concrete samples
under the influence of different mixing sequence, it is recommended that good mixing
sequences, when used should be consistent under a particular job. Mixing sequence 24
had optimum compressive strengths and can be used to make the best concrete.
Uniformity should be checked firstly for fresh concrete properties when determining
which or what mixing sequence to use.
Description
A THESIS SUBMITTED TO THE SCHOOL OF POSTGRADUATE
STUDIES, AHMADU BELLO UNIVERSITY, ZARIA
IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE AWARD
OF MASTER DEGREE IN CONSTRUCTION TECHNOLOGY
DEPARTMENT OF BUILDING,
FACULTY OF ENVIRONMENTAL DESIGN
AHMADU BELLO UNIVERSITY,
ZARIA NIGERIA
Keywords
EFFECT,, MIXING SEQUENCE,, PROPERTIES,, CONCRETE