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Assessing the pumpability of concrete with the slump and pressure bleeding test : research on suitable test methods for assessing the pumpability of concrete

Draijer, W.M. (2007) Assessing the pumpability of concrete with the slump and pressure bleeding test : research on suitable test methods for assessing the pumpability of concrete.

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Abstract:Problems with the pumpability of concrete result in delays, increased costs and more labor. Therefore it is useful to use a test method which can predict if these problems would occur with a batch of concrete. Hereby this batch can be rejected preventing these problems. For this research there will be sought for a test method which can help solving the problems which are present in China. This test method should be useable in-field to assess the pumpability of concrete on the building site. The search for this test method will be done by an analysis of the current problems in China regarding to the pumpability and by creating insights in test methods for the pumpability of concrete. The pumpability of concrete can be described by the consistency and the cohesiveness of this mix. The consistency is the relative ability to flow and in China this is measured by the slump test. The cohesiveness is the resistance to segregation and bleeding. In China this is only measured on request by the normal bleeding test; a time consuming test. Most of the problems which occur in China are not directly related to the consistency or cohesiveness, but to management problems which will finally influence the consistency and cohesiveness of the mix. The management problems causes delays resulting in setting and bleeding of the mix in the truck or the hopper. This results in a change of both the consistency and cohesiveness. Another problem which was met during a visit on the building site was a broken pipe. Combined with high temperatures and a human error this is the last category of problems, ‘other problems’. The problem with high temperatures is that it increases the slump loss and bleeding and thus affects the consistency and cohesiveness of the mix. By the search for a suitable test methods which measure the consistency and cohesiveness all these problems can be dealt with. The test method which shows to be most useful is the combination of the slump- and slump-flow test combined with the pressure bleeding test. These methods are able to measure both the consistency and cohesiveness of different types of concrete. This means that these methods can predict the pumpability of the concrete, independent of the type of problems, and thus prevent blockades from occurring. When slump- and slump-flow test and the pressure bleeding test were tested it appeared that these test methods are reliable test methods. They can measure if recipes are different or identical. Differences in w/b-ratio, sand ratio and a change in the amount of super-plasticizer will give a change in results. These changes showed results as expected. It can be concluded that the slump- and slump-flow test and the pressure bleeding test are useful methods for assessing the consistency and cohesiveness. This means that these methods can be used for assessing the pumpability of concrete. Further improvements for these test methods must be sought in practical improvements. This will make the pressure bleeding test a test method which will be easy and even more reliable to execute. Because of the high future perspective of these tests further development of the tests and research on their correlation to the pumpability of concrete is recommended.
Item Type:Essay (Bachelor)
Faculty:ET: Engineering Technology
Subject:56 civil engineering
Programme:Civil Engineering BSc (56952)
Link to this item:http://purl.utwente.nl/essays/68467
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