RHEOLOGICAL MODEL FOR CONCENTRATED FLOCCULATED SUSPENSION BASED ON FRACTAL CONCEPT

フラクタル理論に基づく濃厚系サスペンジョンのレオロジーモデルの構築

Fresh concretes and cement pastes are considered as non-Newtonian fluids, which show yield stress, thixotropy, and so on. The rheological behaviors of non-Newton fluids are generally evaluated by yield stress and plastic viscosity. On the other hand, the complex flow behaviors mainly attributed by the coagulated or flocculated structure of particles. The authors have adopted a rheological model for concentrated and flocculated suspension based on the formation and the breakup model of fractal flocs in a shear field. However, at low shear rate, the particles form percolating network and the model is not applied. In this study, they proposed a model for predicting yield stresses based on fractal concepts considering the viscoelasticity of flocculated particle chain. The length of particle chain was calculated by applying the concept of fractal blobs in semi-dilute polymer solution. The model was applied to a flocculated aluminum suspensions. The results showed that the fractal dimension was 2.26 at the volume fractions lower than 0.40, but 2.65 at higher than 0.40. This implies that at low shear rate the percolation of flocculated structure of particle in suspension was broken, but maintain the blob structure, whereas with increasing shear rate, the blob was also broken into the rigid structure of which fractal dimension in near 2.86 to 2.98.セメントペーストの流動性は、粒子間の物理的な凝集に基づく凝集構造の変化に大きく依存する。高せん断速度流動時には、凝集サスペンジョンの粘性は独立したフラクタル凝集体間の速度勾配と逸散エネルギーにより予測される。一方で低せん断速度時には粒子がパーコレートを生じ、三次元的に連結した鎖状のネットワーク構造を形成するため弾性的挙動を示す。本研究では準希薄系の高分子溶液中でのブロブの概念を援用し、パーコレートした鎖状粒子の弾性から降伏応力を予測するモデルを用いて、低せん断速度時のフラクタル構造を推定した。その結果、低せん断速度時のフラクタル次元は体積濃度0.40を境として2.26から2.65へと変化することが示された。

• Record URL:
  https://doi.org/10.14250/cement.68.299
• Summary URL:
  http://scholar.google.com/scholar_lookup?title=RHEOLOGICAL+MODEL+FOR+CONCENTRATED+FLOCCULATED+SUSPENSION+BASED+ON+FRACTAL+CONCEPT&author=S.+GOTOH&author=T.+TANAKA&author=M.+ANDO&author=T.+NAWA&publication_year=2014
• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/issn/09163182
• Authors:
  • GOTOH, Suguru
  • TANAKA, Tatsuki
  • ANDO, Masanobu
  • NAWA, Toyoharu
• Publication Date: 2014

Language

• English
• Japanese

Media Info

• Media Type: Digital/other
• Features: Figures; References; Tables;
• Pagination: pp 299-306
• Serial:
  • Cement Science and Concrete Technology
  • Volume: 68
  • Issue Number: 1
  • Publisher: Japan Cement Association
  • ISSN: 0916-3182
  • EISSN: 2187-3313
  • Serial URL: https://www.jstage.jst.go.jp/browse/cement/-char/en
• Publication flags:

  Open Access (libre)

Subject/Index Terms

• TRT Terms: Cement paste; Flocculating agents; Fractals; Fresh concrete; Rheology; Thixotropy; Viscosity; Yield stress
• Subject Areas: Construction; Materials; Transportation (General); I32: Concrete; I50: Construction and Supervision of Construction;

Filing Info

• Accession Number: 01564495
• Record Type: Publication
• Source Agency: Japan Science and Technology Agency (JST)
• Files: TRIS, JSTAGE
• Created Date: May 26 2015 4:12PM