Development and Construction of Low-Cracking High-Performance Concrete (LC-HPC) Bridge Decks: Construction Methods, Specifications, and Resistance to Chloride Ion Penetration

Abstract

The development, construction, and evaluation of Low-Cracking High-Performance Concrete (LC-HPC) bridge decks are described based on laboratory test results and experiences gained through the construction of 14 LC-HPC bridge decks. The study is divided into three parts covering (1) an evaluation of the chloride penetration into concrete using long-term salt-ponding tests, (2) a comprehensive discussion of specifications for LC-HPC construction and standard practices in Kansas, and (3) the description of the construction and the preliminary evaluation of LC-HPC bridge decks in Kansas. This report emphasizes the construction process; a companion report provides a detailed discussion of the influence of material properties on the performance of LC-HPC bridge decks. The first portion of the study involves evaluating the effect of paste content, curing period, water-cement (w/c) ratio, cement type and fineness, mineral admixtures (ground granulated blast furnace slag and silica fume), a shrinkage reducing admixture (SRA), and standard DOT bridge deck mixtures on chloride penetration into solid concrete, tested in accordance with AASHTO T 259. The evaluation includes a total of 33 individual concrete batches and 123 test specimens. The results indicate that for concrete containing only portland cement, reductions in paste content result in increased permeability. A reduced paste content and increased w/c ratio result in increased permeability, whereas the presence of mineral admixtures (ground granulated blast furnace slag and silica fume) and longer curing periods result in decreased permeability. Concrete made with medium or coarse ground Type II cement has greater permeability than concrete made with Type I/II cement. It is not clear how the presence of an SRA affects concrete permeability. LC-HPC mixtures have lower permeability than standard DOT mixtures. The second portion of the study describes the specifications for the LC-HPC and Control bridge decks in Kansas. The focus is on the construction methods, including the evolution of the specifications over time. The third portion of the study details the development and construction of 14 LC-HPC and 12 conventional Control bridge decks built in Kansas. The design details, construction experiences, and lessons learned from the LC-HPC bridge decks are described in detail, and an overview of the materials is presented; the design and construction data for each Control deck is provided; and initial crack survey results are evaluated for various construction-related parameters. The results indicate that that successful LC-HPC bridge deck construction is repeatable and that clear and consistent communication between the contractor, owner, and testing personnel is vital for successful construction of LC-HPC decks. Preliminary evaluation of cracking indicates that at early ages, LC-HPC decks are performing better than the Control decks, as well as earlier monolithic decks in Kansas.