Securing the stable protective pore system of concrete - Report for “Robust Air“ Research Project, 2017

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dc.contributor Aalto-yliopisto fi
dc.contributor Aalto University en Al-Neshawy, Fahim Punkki, Jouni 2017-11-22T10:02:52Z 2017-11-22T10:02:52Z 2017
dc.identifier.isbn 978-952-60-7640-9 (electronic)
dc.identifier.issn 1799-490X (electronic)
dc.identifier.issn 1799-4896 (ISSN-L)
dc.description.abstract Robust Air is a contract research project carried out at Aalto University, Department of Civil Engineering. The project was established due to evelated air content observed in some Finnish concrete structures. The aim of the Robust Air project was to secure the stability of the protective pore system in normal conditions. The stable protective pore system means that the air content or pore size distribution are not significantly changing after mixing of concrete. The main part of the research was made in the laboratory tests which were divided into two parts. In the first part the concrete properties were altered and the same admixtures were used. In the admixture tests the concrete properties were kept constant and the admixtures were altered. The main interest of the laboratory tests was to analyze the air content of concrete as function of time. The measurements were carried out immediately after mixing, 30 min and 60 min and finally 75 min after mixing. In addition to the air content, also sensitivity for segregation was analyzed. In addition to the laboratory tests, factory tests the Finnish concrete industry made tests in which the air content of concrete was measured after normal mixing time but also after 6 min mixing time.  Based on the experiments, it was observed that the mixing process of the air-entrained concrete is not necessarily effective enough. It is possible that only part of the entrained air is formed during the mixing process and there is a risk for elevated air content when the concrete is mixing in the concrete truck. The phenomenon was explained by air content potential. Each concrete has an air content potential (maximum air content) which depends on the admixture combination, concrete composition and the consistency of concrete. A relative effective mixing process is needed to achieve the Air content potential during the mixing process. And if the potential is not reached during the mixing process, there is a risk that the air content may increase later when the concrete is mixed in the truck.  Recommendations were given to minimize the risk for elevated air contents. The recommendations include development actions related to admixtures, concrete mixers, quality control systems and to requirements of frost resistance concrete. The concrete producers need to take the phenomenon better into account in the concrete manufacturing process. en
dc.format.extent 100 + app. 5
dc.format.mimetype application/pdf en
dc.language.iso en en
dc.publisher Aalto University en
dc.publisher Aalto-yliopisto fi
dc.relation.ispartofseries Aalto University publication series SCIENCE + TECHNOLOGY en
dc.relation.ispartofseries 10/2017
dc.subject.other Civil engineering en
dc.subject.other Materials science en
dc.title Securing the stable protective pore system of concrete - Report for “Robust Air“ Research Project, 2017 en
dc.type D4 Julkaistu kehittämis- tai tutkimusraportti tai -selvitys fi Insinööritieteiden korkeakoulu fi School of Engineering en
dc.contributor.department Rakennustekniikan laitos fi
dc.contributor.department Department of Civil Engineering en
dc.subject.keyword air content en
dc.subject.keyword superplasticizer en
dc.subject.keyword air-entraining en
dc.subject.keyword admixtures en
dc.subject.keyword cement en
dc.subject.keyword mix design en
dc.subject.keyword testing en
dc.identifier.urn URN:ISBN:978-952-60-7640-9
dc.type.dcmitype text en

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