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Workability of air entrained high performance concrete
Air entrainment is essential for the durability of high performance concrete (HPC) that became wetted and then exposed to freeze-thaw conditions. Air entrainment essential accomplished by the use of air entraining agent (AE). The main effect of air entrainment is the great improvement of the durability of HPC to freezing exposures; however, air entrainment influences significantly workability of fresh HPC. In order to adjust workability of air entrained HPC, the knowledge on how AE influences the rheological properties of fresh HPC mix is necessary. This paper reports the results of a preliminary study into the influence of AE rheological properties of concrete mix with different cement - superplasticizer systems. Influence of AE was studied using Rheometrical Workability Test (RWT), modified mortars acc. PN EN 196-1:1996, which can be considered as a model of fresh HPC. Following factors were taken into consideration in the research: AE type dosage, cement composition and specific surface, and SP type. The obtained results establish that rheological properties of air entrained fresh HPC depends successively on: properties of cement and SP, dosage and type of AE and compatibility of the AE with the cement - SP system. On the ground of obtained results, the authors worked out basic relationships of AE influence on the rheological properties of fresh HPC, and proposed the method of correction of the effects of AE on workability and, simultaneously, on compressive strength of HSC. Discussion of the results covers: mechanism of AE influence on rheological parameters of fresh HPC, and possible consequences of AE addition for workability of fresh HPC. It is concluded that AE usage usually significantly change HPC workability. Presented in the paper basic relationships can be used in practice for adjusting workability of air entrained HPC. However, due variety of AE, problems with identification components of AE, and possibility of interaction between AE and cement - SP system, influence of AE on workability of given HPC should be experimentally verified. RWT performed on model mortars can be a useful tool for such verification, providing information on changes of rheological properties of air entrained fresh HPC in particular technological conditions.
Workability of air entrained high performance concrete
Air entrainment is essential for the durability of high performance concrete (HPC) that became wetted and then exposed to freeze-thaw conditions. Air entrainment essential accomplished by the use of air entraining agent (AE). The main effect of air entrainment is the great improvement of the durability of HPC to freezing exposures; however, air entrainment influences significantly workability of fresh HPC. In order to adjust workability of air entrained HPC, the knowledge on how AE influences the rheological properties of fresh HPC mix is necessary. This paper reports the results of a preliminary study into the influence of AE rheological properties of concrete mix with different cement - superplasticizer systems. Influence of AE was studied using Rheometrical Workability Test (RWT), modified mortars acc. PN EN 196-1:1996, which can be considered as a model of fresh HPC. Following factors were taken into consideration in the research: AE type dosage, cement composition and specific surface, and SP type. The obtained results establish that rheological properties of air entrained fresh HPC depends successively on: properties of cement and SP, dosage and type of AE and compatibility of the AE with the cement - SP system. On the ground of obtained results, the authors worked out basic relationships of AE influence on the rheological properties of fresh HPC, and proposed the method of correction of the effects of AE on workability and, simultaneously, on compressive strength of HSC. Discussion of the results covers: mechanism of AE influence on rheological parameters of fresh HPC, and possible consequences of AE addition for workability of fresh HPC. It is concluded that AE usage usually significantly change HPC workability. Presented in the paper basic relationships can be used in practice for adjusting workability of air entrained HPC. However, due variety of AE, problems with identification components of AE, and possibility of interaction between AE and cement - SP system, influence of AE on workability of given HPC should be experimentally verified. RWT performed on model mortars can be a useful tool for such verification, providing information on changes of rheological properties of air entrained fresh HPC in particular technological conditions.
Workability of air entrained high performance concrete
Verarbeitbarkeit von Hochleistungs-Luftporenbeton
Golaszewski, Jacek (author) / Szwabowski, Janusz (author)
2004
13 Seiten, 9 Bilder, 4 Tabellen, 8 Quellen
Conference paper
English
Workability of air-entrained lightweight concrete from rheology perspective
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