<?xml version="1.0" encoding="utf-8"?>
<export-example>
  <doc>
    <id>5531</id>
    <completedYear/>
    <publishedYear>2023</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst>1</pageFirst>
    <pageLast>10</pageLast>
    <pageNumber/>
    <edition/>
    <issue/>
    <volume>131</volume>
    <type>article</type>
    <publisherName>Elsevier</publisherName>
    <publisherPlace/>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>--</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">On the significance of accelerator enriched layers in wet-mix shotcrete</title>
    <abstract language="eng">The application process, which gives shotcrete its name is a robust and established method, dating back to the beginning of the 20th century. Since then, the spraying process has been significantly enhanced. However, during the last decades no major technical changes have been made. In this study the wet - mix shotcrete process including the dosing of accelerator was investigated. For this, we monitored the concrete and accelerator pressure with 5 sensors in the pumps and pipes, and analysed the accelerator distribution in the hardened shotcrete matrix. The recorded pressure fluctuations clearly indicated that the pumping of the concrete with a double-piston pump led to flow pulsations. The pressure along the accelerator pipes, controlled by a peristaltic pump, was not steady either. However, the accelerator flow pulsation had a higher frequency than that of the concrete flow. This misalignment led to changes in the accelerator to concrete ratio during the spraying process. The impact of these incongruent concrete and accelerator flows on the resulting hardened shotcrete was visually analysed with the use of 0.02 % uranin as fluorescent tracer added to the accelerator. The tracer distribution showed that changes in the accelerator/concrete ratio led to the formation of ‘accelerator layers’, layers with higher accelerator concentrations in the hardened shotcrete. These layers show differences in chemistry, mineralogy and open porosity compared to the rest of the shotcrete matrix. The presence of accelerator enriched layers can have detrimental effects on the shotcrete properties, especially affecting the durability and mechanical performance. In consequence, we recommend a revision of the shotcrete process to eliminate these inhomogeneities.</abstract>
    <parentTitle language="eng">Tunnelling and Underground Space Technology</parentTitle>
    <identifier type="doi">10.1016/j.tust.2022.104764</identifier>
    <enrichment key="opus.import.date">2022-10-28T17:12:32+00:00</enrichment>
    <enrichment key="opus.source">sword</enrichment>
    <enrichment key="opus.import.user">importuser</enrichment>
    <enrichment key="BegutachtungStatus">peer-reviewed</enrichment>
    <licence>Creative Commons - CC BY - Namensnennung 4.0 International</licence>
    <author>Marlene Sakoparnig</author>
    <author>Isabel Galan</author>
    <author>Wolfgang Kusterle</author>
    <author>Benedikt Lindlar</author>
    <author>Günther Koraimann</author>
    <author>Thomas Angerer</author>
    <author>Florian Roman Steindl</author>
    <author>Lukas G. Briendl</author>
    <author>Sebastian Jehle</author>
    <author>Johannes Flotzinger</author>
    <author>Joachim Juhart</author>
    <author>Florian Mittermayr</author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Inhomogeneities</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Pulsation</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Concrete pumping</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Layering</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Accelerator</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Shotcrete</value>
    </subject>
    <collection role="institutes" number="FakBau">Fakultät Bauingenieurwesen</collection>
    <collection role="othforschungsschwerpunkt" number="16313">Gebäude und Infrastruktur</collection>
    <collection role="oaweg" number="">Hybrid Open Access - OA-Veröffentlichung in einer Subskriptionszeitschrift/-medium</collection>
    <collection role="institutes" number="">Labor für Baustoffe</collection>
  </doc>
  <doc>
    <id>6117</id>
    <completedYear/>
    <publishedYear>2023</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst/>
    <pageLast/>
    <pageNumber/>
    <edition/>
    <issue/>
    <volume>368</volume>
    <type>article</type>
    <publisherName>Elsevier</publisherName>
    <publisherPlace>14</publisherPlace>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>--</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">On the porosity of low-clinker shotcrete and accelerated pastes</title>
    <abstract language="eng">Although the number and size of interconnected pores have been identified as the most important aspects of concrete microstructure, comprehensive datasets on shotcrete porosity and pore size distributions are still scarce and their key controls are poorly investigated. In this study we investigate the effects of the spraying process, setting accelerator addition and mix design on the microstructure of real-scale dry- and wet-mix shotcrete and hand-mixed and sprayed accelerated pastes. A newly proposed deconvolution analysis of the pore size distributions, measured by mercury intrusion porosimetry, offers increased precision in determining the critical and median pore diameter parameters. In total &gt;50 samples were analysed. Results show that the dry-mix shotcrete exhibits a shift towards coarser pore sizes (∼100–1 μm) than wet-mix shotcrete. Combinations of different supplementary cementitious materials are favourable for producing wet-mix shotcretes with refined pore structures. The addition of setting accelerators, up to 10 wt-% of binder mass, and the spraying process cause systematic variations in the pore volume and pore structure of (sprayed) paste and shotcrete.</abstract>
    <parentTitle language="eng">Construction and Building Materials</parentTitle>
    <identifier type="issn">0950-0618</identifier>
    <identifier type="doi">10.1016/j.conbuildmat.2023.130461</identifier>
    <enrichment key="opus.import.data">@article WOS:000926759600001, Author = Steindl, Florian R. and Mittermayr, Florian and Sakoparnig, Marlene and Juhart, Joachim and Briendl, Lukas and Lindlar, Benedikt and Ukrainczyk, Neven and Dietzel, Martin and Kusterle, Wolfgang and Galan, Isabel, Title = On the porosity of low-clinker shotcrete and accelerated pastes, Journal = CONSTRUCTION AND BUILDING MATERIALS, Year = 2023, Volume = 368, Month = MAR 3, Abstract = Although the number and size of interconnected pores have been identified as the most important aspects of concrete microstructure, comprehensive datasets on shotcrete porosity and pore size distributions are still scarce and their key controls are poorly investigated. In this study we investigate the effects of the spraying process, setting accelerator addition and mix design on the microstructure of real-scale dry- and wet-mix shotcrete and hand-mixed and sprayed accelerated pastes. A newly proposed deconvolution analysis of the pore size distributions, measured by mercury intrusion porosimetry, offers increased precision in determining the critical and median pore diameter parameters. In total &gt;50 samples were analysed. Results show that the dry-mix shotcrete exhibits a shift towards coarser pore sizes (similar to 100-1 mu m) than wet-mix shotcrete. Combinations of different supplementary cementitious materials are favourable for producing wet-mix shotcretes with refined pore structures. The addition of setting accelerators, up to 10 wt-% of binder mass, and the spraying process cause systematic variations in the pore volume and pore structure of (sprayed) paste and shotcrete., DOI = 10.1016/j.conbuildmat.2023.130461, Article-Number = 130461, ISSN = 0950-0618, EISSN = 1879-0526, Unique-ID = WOS:000926759600001,</enrichment>
    <enrichment key="opus.import.dataHash">md5:a2a1af9a48ea20e4b2e55e52f326ca6b</enrichment>
    <enrichment key="opus.import.date">2023-06-30T11:21:46+00:00</enrichment>
    <enrichment key="opus.import.file">/tmp/phpyD7xJy</enrichment>
    <enrichment key="opus.import.format">bibtex</enrichment>
    <enrichment key="opus.import.id">649ebacaa12bd4.39499150</enrichment>
    <enrichment key="BegutachtungStatus">peer-reviewed</enrichment>
    <enrichment key="opus.doi.autoCreate">false</enrichment>
    <enrichment key="opus.urn.autoCreate">true</enrichment>
    <licence>Creative Commons - CC BY - Namensnennung 4.0 International</licence>
    <author>Florian R. Steindl</author>
    <author>Florian Mittermayr</author>
    <author>Marlene Sakoparnig</author>
    <author>Joachim Juhart</author>
    <author>Lukas G. Briendl</author>
    <author>Benedikt Lindlar</author>
    <author>Neven Ukrainczyk</author>
    <author>Martin Dietzel</author>
    <author>Wolfgang Kusterle</author>
    <author>Isabel Galan</author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Porosity</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Shotcrete</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Mercury Intrusion</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Durability</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>SCMs</value>
    </subject>
    <collection role="institutes" number="FakBau">Fakultät Bauingenieurwesen</collection>
    <collection role="othforschungsschwerpunkt" number="16313">Gebäude und Infrastruktur</collection>
    <collection role="oaweg" number="">Hybrid Open Access - OA-Veröffentlichung in einer Subskriptionszeitschrift/-medium</collection>
  </doc>
</export-example>
