Unified Shrinkage Model for Concrete from Autogenous Shrinkage Test on Paste with and without Ground-Granulated Blast-Furnace Slag

ABOUT THE INTERNATIONAL CONCRETE ABSTRACTS PORTAL

  • The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.

International Concrete Abstracts Portal

  


Title: Unified Shrinkage Model for Concrete from Autogenous Shrinkage Test on Paste with and without Ground-Granulated Blast-Furnace Slag

Author(s): Ya Wei, Will Hansen, Joseph J. Biernacki, and Erik Schlangen

Publication: Materials Journal

Volume: 108

Issue: 1

Appears on pages(s): 13-20

Keywords: aggregate; autogenous shrinkage; ground-granulated blast-furnace slag; hydration products; self-desiccation; shrinkage modeling

Date: 1/1/2011

Abstract:
Autogenous shrinkage development was studied as a function of time for cement paste and concrete hydrating under sealed conditions at room temperature. Effects of water-cementitious material ratio (w/cm) (0.35, 0.40, and 0.45), ground-granulated blast-furnace slag (GGBFS) content as a percentage of total cementitious material (0, 30, and 50%) by mass, and aggregate content (40%) by volume on shrinkage development was obtained. Shrinkage measurements started after 10 hours and lasted up to 90 days. Self-desiccation (that is, reduction in pore humidity) was predicted using the HYMOSTRUC model. The effects of w/cm on shrinkage development can be normalized from shrinkage versus pore humidity curves for portland-cement paste. The aggregate effect on autogenous shrinkage was found to follow a Pickett model developed for drying shrinkage. These results suggest that a unified shrinkage model, which combines autogenous and drying shrinkage, exists. The framework for such a model is presented, which incorporates relative humidity (RH), aggregate content, and restraint factor as major variables. GGBFS initially reduces shrinkage as it behaves as a filler, thus increasing the effective w/cm. While the long-term shrinkage is increased, the major factor is most likely a reduction in pore humidity associated with pozzolanic reactions. Due to a higher internal RH in a 0.45 w/cm system, the pozzolanic effect on autogenous shrinkage is more pronounced at later ages.