1 / 26

A MACRO-MODEL FOR SELF-DESICCATION IN HIGH PERFORMANCE CONCRETE

A MACRO-MODEL FOR SELF-DESICCATION IN HIGH PERFORMANCE CONCRETE. Lars-Olof Nilsson Div. of Building Materials Lund Institute of Technology Lund University. Kristina Mjörnell Dept. of Building Physics Swedish National Testing and Research Institute, Borås. Outline. 1. Introduction

hayden-fulton
Download Presentation

A MACRO-MODEL FOR SELF-DESICCATION IN HIGH PERFORMANCE CONCRETE

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. A MACRO-MODEL FOR SELF-DESICCATION IN HIGH PERFORMANCE CONCRETE Lars-Olof Nilsson Div. of Building Materials Lund Institute of Technology Lund University Kristina Mjörnell Dept. of Building Physics Swedish National Testing and Research Institute, Borås A MACRO-MODEL FOR SELF-DESICCATION IN HPC

  2. Outline 1. Introduction 2. The model for self-desiccation 3. Physical binding of water 4. Chemical binding of water 5. Internal curing 6. Predictions with the model 7. Conclusion A MACRO-MODEL FOR SELF-DESICCATION IN HPC

  3. HPC in Sweden • A few important marine concrete structures where a service-life of some 100 years is required in harsh marine environments (a SRPC/silica fume HPC) • 1000’s of concrete floor slabs where a moisture sensitive flooring is to be used (OPC HPC; w/C  0.40: Main reason for using HPC is the controlled and rapid drying by self-desiccation. A MACRO-MODEL FOR SELF-DESICCATION IN HPC

  4. Drying of HPC HPC NC A MACRO-MODEL FOR SELF-DESICCATION IN HPC

  5. Really true? Dominating mix parameters for self-desiccation cement type and w/c A MACRO-MODEL FOR SELF-DESICCATION IN HPC

  6. Self-desiccation in the sorption isotherm A MACRO-MODEL FOR SELF-DESICCATION IN HPC

  7. where The model for self-desiccation A MACRO-MODEL FOR SELF-DESICCATION IN HPC

  8. Alkali effect Physical binding of water we Scap we/C A MACRO-MODEL FOR SELF-DESICCATION IN HPC

  9. Desorption isotherms for HPCf(w/B, Si) A MACRO-MODEL FOR SELF-DESICCATION IN HPC

  10.  the desorption isotherm at different ages The model for self-desiccation A MACRO-MODEL FOR SELF-DESICCATION IN HPC

  11. Desorption isotherms for HPCat early ages (room temperature) A MACRO-MODEL FOR SELF-DESICCATION IN HPC

  12. where = chemical binding of water at different T & RH(t) The model for self-desiccation A MACRO-MODEL FOR SELF-DESICCATION IN HPC

  13. Chemical binding of water A MACRO-MODEL FOR SELF-DESICCATION IN HPC

  14. Chemical binding of waterlack of space bw/c ac A MACRO-MODEL FOR SELF-DESICCATION IN HPC

  15. carbonation? Chemical binding of watermoisture effects wn/C(RH, t1) bRH A MACRO-MODEL FOR SELF-DESICCATION IN HPC

  16. TGA-studies on reactivity at shortage of water Norling-Mjörnell (1997) SRPC, w/C=0.3, 5% Si-fume A MACRO-MODEL FOR SELF-DESICCATION IN HPC

  17. OPC Mjörnell (1997) Chemical binding of watermoisture effects wn/C(RH, t1) bRH A MACRO-MODEL FOR SELF-DESICCATION IN HPC

  18. OPC Si-fume Mjörnell (1997) Chemical binding of watermoisture effects wn(RH, t1) bRH A MACRO-MODEL FOR SELF-DESICCATION IN HPC

  19. Chemical binding of watermoisture effects wn(RH, t1) bRH alkali effect? f(a) A MACRO-MODEL FOR SELF-DESICCATION IN HPC

  20. cf. Snyder & Bentz(2004) Chemical binding of watermoisture effects bf,w ac A MACRO-MODEL FOR SELF-DESICCATION IN HPC

  21. Chemical binding of watertemperature effects A MACRO-MODEL FOR SELF-DESICCATION IN HPC

  22. Predictions with the model- cement hydration ac w/c 0.4 OPC A MACRO-MODEL FOR SELF-DESICCATION IN HPC

  23. Predictions with the model- self-desiccation, room temperature A MACRO-MODEL FOR SELF-DESICCATION IN HPC

  24. Predictions with the model- cement hydration, curing effects ac SRPC with w/c 0.4 A MACRO-MODEL FOR SELF-DESICCATION IN HPC

  25. Predictions with the model- self-desiccation, low temperature But later findings indicate quite another low-temperature curing effect! cf. Persson (2005) SRPC with w/c 0.4 A MACRO-MODEL FOR SELF-DESICCATION IN HPC

  26. Conclusions • The model for self-desiccation seems very promising and potentially useful for many applications of HPC • The model is especially designed for concrete floor slabs, where self-desiccation is beneficial. • Could very well be applied to concrete structures of HPC were the main concern of self-desiccation is shrinkage and early age cracking, and including internal curing. • The model can easily be integrated into a model that includes moisture transport (has been done!) • The most uncertain part of the model is the moisture effect on rate of reaction, where more research is needed, especially at very early ages. • The effect of early curing at low temperature may require special attention! A MACRO-MODEL FOR SELF-DESICCATION IN HPC

More Related