Dissertation > Excellent graduate degree dissertation topics show

The Composition and Structure of Interfacial Transition Zone in Harden Concrete Exposed to Alkaline Environment

Author: WangXiaoHai
Tutor: ZhanBingGen
School: Hefei University of Technology
Course: Structural Engineering
Keywords: Concrete Alkaline Interfacial Transition Zone Hydrate Pore structure Element distribution
CLC: TU528.45
Type: Master's thesis
Year: 2009
Downloads: 99
Quote: 2
Read: Download Dissertation

Abstract


Interfacial Transition Zone (ITZ) plays an important role in concrete. High-alkaline environment may cause changes in ITZ, thus affect the performance of concrete. It is necessary to investigate the changes of ITZ exposed to alkaline environment for the purpose of understanding the mechanism of alkali-silica reaction(ASR).In this paper, concrete respectively prepared with one non-reactive limestone aggregate and two active aggregates of zeolite and crystal glass were exposed to various concentrations of alkali solutions. The composition and structure of ITZ in the conctete were investigated and compare with each other. SEM / EDS was used to observe and analyze the morphology and composition of hydrates in ITZ. SEM-BSE was used to study the effects caused by different aggregate and alkali concentration on the pore structure of ITZ. X-ray tomography was used to analyze the orientation of the calcium hydroxide and the average size of the ettringite (Aft). The re-distribution of the material base on distribution of the elements of ITZ were also inverstigated.The results show that there is no significant difference among morphology of hydrate in the ITZ of ordinary concrete at various concentrations of alkali solution, while the morphology of calcium silicate hydrate in alkaline-active concrete is various, especially in the high alkaline environment. The calcium hydroxide (CH) which is hexagonal prism morphology was difficult to find and so did needle like ettringite. The orientation of the CH in ITZ is obvious. The grains of CH and AFt were refined obviously. The porosity of ITZ in alkaline-activity concrete decreased compare with that in ordinary concrete, but the number of more hazardous holes significantly improved. The ITZ in alkaline-activity concrete with high Ca/Si, high sodium concentration and low aluminum content is prone to induse ASR.These characteristics of ITZ in alkaline environment provide theoretical and experimental bases for explaining various changes of properties of concrete, especially for analyzing the mechanism of ASR and finding methods to prevent ASR.

Related Dissertations

  1. Analysis and Study of Abutment Stability in Concrete High Arch Dam by Three-Dimensional Nonlinear Finite Element Method,TV642.4
  2. Partical Combination of Fine Powder Effect on Performance of Cement and Concrete,TU528.041
  3. The Studies and Establishment of Ready-mixed Concrete Information-guided Price on the Basis of Risk Analysis,F407.92
  4. Rock-fill Concrete Experiments on Comprehensive Properties and Studies on Thermal Stress,TU528
  5. Experimental Study of Porous Composite Materials on the Base of Recycled Concrete Powder-Cement,TU528
  6. The Experimental Research on Regeneration Aggregate and Proportioning of Recycled Concrete Brick,TU528
  7. Experiments on Microwave Radiation Activation YunNan Unburned Coal-gangue Concrete,TU528
  8. Recycled aggregate semi- rigid concrete preparation and molding of test,TU528
  9. Applied research in the sugar cane juice clarification process of alkaline pectinase,TS244.2
  10. Preparation of Activated Carbon from Tobacco Stems and Application for Low Concentration Phosphine Adsorption,X712
  11. Analysis of Concrete Durability under Combined Action of Freeze-thaw Cycles and Chloride Ion Erosion,TU528
  12. The Research of Concrete Shrinkage and Creep Experiment,TU528
  13. Rate-dependent Endochronic Damage Constitutive Model for Concrete,TU528
  14. The Research on the Effect of Uniaxial Compressive Load and Mineral Admixtures on Chloride Permeability of Concrete,TU528
  15. The Synthrsis of Novel Purine Nucleoside Modified by C~6-Alkyl and C~6-Heterocyclic,TQ460.1
  16. Flow injection spectrophotometric determination of organophosphorus pesticides in environmental water research,O657.32
  17. Studies on the Public Service Barrister System of China,D926.5
  18. Study of the Civil Judicial Activism,D926
  19. Research on Early Age Shrinkage-Cracking Characterization of Concrete with Multi-Components Admixtures,TU528
  20. Experimental Studies on High Temperature Material、 Carbonization and Flexural Behavior of Flexural Member of RAC,TU528
  21. (Class ) perovskite -type oxides catalytic elimination of N 2 O,X701

CLC: > Industrial Technology > Building Science > Building Materials > Non-metallic materials > Concrete and concrete products > Silicate concrete > Cement concrete
© 2012 www.DissertationTopic.Net  Mobile