Internal Curing and Microstructure of High-Performance Mortars

While typically used to reduce early-age autogenous shrinkage and cracking, internal curing will also strongly influence the microstructure that is produced in cement-based materials. In this paper, the microstructure of a set of three different blended cement high performance mortars produced with and without internal curing will be compared. For these mortars with a water-to-cementitious materials ratio of 0.3 by mass, internal curing has been provided by the addition of pre-wetted lightweight fine aggregates. Their microstructures have been examined after 120 days of sealed curing using scanning electron microscopy of polished surfaces in the back-scattered electron imaging mode. Clear distinctions between the microstructures produced with and without internal curing are noted, including differences in the unreacted cementitious content, the porosity, and the microstructure of the interfacial transition zones between sand grains (normal and lightweight) and the hydrated cement paste. These microstructural observations will be related to previously measured performance attributes such as autogenous deformation and compressive strength development.

[1]  Abraham S. Grader,et al.  Water Movement During Internal Curing: Direct Observation Using X-Ray Microtomography , 2006 .

[2]  K. Kovler,et al.  Prevention of autogenous shrinkage in high-strength concrete by internal curing using wet lightweight aggregates , 2001 .

[3]  Odd E. Gjørv,et al.  Microstructure of the interfacial zone between lightweight aggregate and cement paste , 1990 .

[4]  Pietro Lura,et al.  Autogenous Deformation and Internal Curing of Concrete , 2003 .

[5]  K. Kjellsen,et al.  Pore structure of cement silica fume systems Presence of hollow-shell pores 1 1 This paper was origi , 1999 .

[6]  Pierre-Claude Aitcin,et al.  Effect of Saturated Lightweight Sand Substitution on Shrinkage in 0.35 w/b Concrete , 2007 .

[7]  Dale P. Bentz,et al.  Internal Curing of High-Performance Blended Cement Mortars , 2007 .

[8]  D. Bentz,et al.  Curing, Hydration, and Microstructure of Cement Paste , 2006 .

[9]  Edward J. Garboczi,et al.  Estimation of the degree of hydration of blended cement pastes by a scanning electron microscope point-counting procedure , 2004 .

[10]  E. Landis,et al.  Microstructural features of a mortar as seen by computed microtomography , 2007 .

[11]  Hans W. Reinhardt,et al.  A New Generation of High Performance Concrete: Concrete with Autogenous Curing , 1997 .

[12]  David A. Crocker,et al.  Better Pavements through Internal Hydration , 2007 .

[13]  P. Stutzman,et al.  SEM Analysis and Computer Modelling of Hydration of Portland Cement Particles , 1994 .