Internal Curing Of Concrete With Presaturated LWA: A Preliminary Investigation

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Title: Internal Curing Of Concrete With Presaturated LWA: A Preliminary Investigation

Author(s): Liberato Ferrara; Luca Cortesi and Omar Ligabue

Publication: Special Publication

Volume: 305

Issue:

Appears on pages(s): 12.1-12.12

Keywords: Internal Curing, autogenous shrinkage, light weight aggregate, early age cracking, high performance concrete, durability

Date: 9/1/2015

Abstract:
Advances in concrete technology have led to a widespread use of High Performance Concretes (HPC) with a low water/binder ratio. Those concretes are prone to early age cracking because of the increased autogenous shrinkage, which is normally insignificant for w/b greater than 0.4 and appears mostly in the first days after setting, when the concrete has not reached its full tensile strength, and so it’s one of the principal causes of early age cracking impairing the structure durability. This study aims at quantifying the efficiency of Internal Curing with pre-saturated Light Weight Aggregates (LWA) on the reduction of autogenous shrinkage in HPC. A standard mixture (w/c = 0.3) was tested together with an Internal Cured one, in which a fraction of the normal weight aggregate was replaced by a pre-wetted LWA, to evaluate the differences in the mechanical properties (compressive and tensile strength, elastic modulus) and shrinkage behavior (plastic, autogenous, drying free and restrained shrinkage). In face of a slight decrease of the strength (about 9%) which did not compromise the structural use of the concrete, the pre-wetted LWA led to a 30% decrease of autogenous shrinkage, and a roughly 50% reduction in cracking potential.