01045580

Component

Many state highway agencies have implemented high performance concrete (HPC) for bridge decks. The low permability of HPC is used to protect reinforcing steel and prevent corrosion. However, if the concrete cracks, then the protection is may be greatly diminished. One unintended consequence of the use of high performance concrete is early-age cracking. Internal curing using lightweight aggregate (LWA) or superabsorbent polymers (SAP) has been proposed to mitigate cracking of HPC due to autogenous shrinkage. ODOT’s District 12, located in Northeastern Ohio, found in an investigation of 116 HPC bridge decks placed between 1994 and 2001 that bridges with little or no cracking used coarse aggregate with an absorption > 1 %, while 75 % of bridges with unacceptable cracking used coarse aggregate with absorption < 1 %. This paper discusses the laboratory investigation of the field results to determine the better ways to prevent bridge deck cracking – internal curing or paste reduction by using an aggregate blend. The laboratory investigation found that the strongest effect on cracking was due to the replacement of a small maximum size coarse aggregate with an aggregate blend. Increasing the coarse aggregate absorption level from < 1% to > 1% had a less dramatic effect. The use of LWA for internal curing to the low absorption coarse aggregate also had a less dramatic effect.

01042056

07-0953

English

15p

2007

Transportation Research Board 86th Annual Meeting

CD-ROM

Figures; Photos; References (20) ; Tables (5)

Absorbents; Blending; Blends; Bridge decks; Coarse aggregates; Concrete bridges; Cracking; Fracture mechanics; High performance concrete; Lightweight aggregates

Early age (Concrete); Early age cracking

Bridges and other structures; Design; Highways; Materials; I24: Design of Bridges and Retaining Walls; I32: Concrete

Transportation Research Board Annual Meeting 2007 Paper #07-0953

PRP, TRIS, TRB

Feb 8 2007 5:32PM