Influence of Ultrafine Fly Ash on the Early Age Response and the Shrinkage Cracking Potential of Concrete

In this paper, the influence of ultrafine fly ash on the early age property development, shrinkage, and shrinkage cracking potential of concrete is investigated. In addition, the performance of ultrafine fly ash as cement replacement is compared with that of silica fume. The mechanisms responsible for an increase of the early age stress due to restrained shrinkage were assessed; free shrinkage and elastic modulus were measured from an early age. In addition, the materials resistance to tensile fracture and increase in strength were also determined as a function of age. Results of the experimental study indicate that the increase in elastic modulus and fracture resistance with age are comparable for the control, ultrafine fly ash, and silica fume concretes. Autogenous shrinkage is shown to play a significant role in determining the age of cracking in restrained shrinkage tests. A significant reduction in the autogenous shrinkage and an increase in the age of restrained shrinkage cracking were observed in the ultrafine fly ash concrete when compared with the control and the silica fume concrete. Increasing the volume of ultrafine fly ash and decreasing the ratio of water-to-cementitous materials resulted in further increase in the age of restrained shrinkage cracking and a significant increase in the compressive strength.

[1]  Mohamed Lachemi,et al.  Determination of the coefficient of thermal expansion of high performance concrete from initial setting , 2002 .

[2]  R. Helmuth,et al.  Fly Ash in Cement and Concrete , 1987 .

[3]  T. Naik,et al.  EFFECTS OF HIGH-LIME FLY ASH CONTENT ON WATER DEMAND, TIME OF SET, AND COMPRESSIVE STRENGTH OF CONCRETE , 1990 .

[4]  R. Carrasquillo,et al.  Strength and Durability Considerations Affecting Mix Proportioning of Concrete Containing Fly Ash , 1988 .

[5]  J. Monzó,et al.  Early-strength development of portland cement mortars containing air classified fly ashes , 1995 .

[6]  W. Jason Weiss,et al.  Shrinkage Cracking of Restrained Concrete Slabs , 1998 .

[7]  E. Tazawa.  Effect of chemical composition and particle size of fly ash on autogenous shrinkage of paste , 1999 .

[8]  Š. Slanička,et al.  The influence of fly ash fineness on the strength of concrete , 1991 .

[9]  M N Haque,et al.  Fly Ash Reduces Harmful Chloride Ions in Concrete , 1992 .

[10]  T. Naik,et al.  Influence of Fly Ash on Setting and Hardening Characteristics of Concrete Systems , 1997 .

[11]  Rachel J. Detwiler,et al.  Cracking Tendency and Drying Shrinkage of Silica Fume Concrete for Bridge Deck Applications , 2000 .

[12]  Surendra P. Shah,et al.  Two Parameter Fracture Model for Concrete , 1985 .

[13]  Sreenivas Alampalli,et al.  In-Service Performance of High-Performance Concrete Bridge Decks , 2000 .

[14]  François de Larrard,et al.  Ultrafine particles for the making of very high strength concretes , 1989 .

[15]  Obada Kayali,et al.  Properties of high-strength concrete using a fine fly ash , 1998 .

[16]  Surendra P. Shah,et al.  Determination of fracture parameters (KIcs and CTODc) of plain concrete using three-point bend tests , 1990 .

[17]  H. Uchikawa,et al.  Influence of microstructure on the physical properties of concrete prepared by substituting mineral powder for part of fine aggregate , 1996 .

[18]  Christopher M Waszczuk.  Crack Free HPC Bridge Deck—New Hampshire’s Experience , 2005 .

[19]  Chiara F. Ferraris,et al.  The influence of mineral admixtures on the rheology of cement paste and concrete , 2001 .

[20]  Youjun Xie,et al.  Influence of ultrafine fly ash composite on the fluidity and compressive strength of concrete , 2000 .

[21]  V. Malhotra,et al.  Fly Ash for Use in Concrete - A Critical Review , 1980 .

[22]  P. K. Mehta.  Influence of fly ash characteristics on the strength of portland-fly ash mixtures , 1985 .

[23]  W. Jason Weiss,et al.  Influence of specimen size/geometry on shrinkage cracking of rings , 2000 .

[24]  V. M. Malhotra,et al.  Long-term strength development of high-volume fly ash concrete , 1990 .