Assessment of recycled concrete aggregates as a pavement material

Population increase and economic developments can lead to construction as well as demolition of infrastructures such as buildings, bridges, roads, etc resulting in used concrete as a primary waste product. Recycling of waste concrete to obtain the recycled concrete aggregates (RCA) for base and/or sub-base materials in road construction is a foremost application to be promoted to gain economical and sustainability benefits. As the mortar, bricks, glass and reclaimed asphalt pavement (RAP) present as constituents in RCA, it exhibits inconsistent properties and performance. In this study, six different types of RCA samples were subjected classification tests such as particle size distribution, plasticity, compaction test, unconfined compressive strength (UCS) and California bearing ratio (CBR) tests. Results were compared with those of the standard road materials used in Queensland, Australia. It was found that material type ‘RM1-100/RM3-0’ and ‘RM1-80/RM3-20’ samples are in the margin of the minimum required specifications of base materials used for high volume unbound granular roads while others are lower than that the minimum requirement.

Investigation on characteristics and performance of recycled concrete aggregates as granular materials for unbound pavements

This research was a step forward in investigating the characteristics of recycled concrete aggregates to use as an unbound pavement material. The results present the guidelines for successfully application of recycled concrete aggregates in high traffic volume roads. Outcomes of the research create more economical and environmental benefits through reducing the depletion of natural resources and effectively manage the generated concrete waste before disposal as land fill.

Compatibility of ultra high performance concrete as repair material : bond characterization with concrete under different loading scenarios

The rehabilitation of concrete structures, especially concrete bridge decks, is a major challenge for transportation agencies in the United States. Often, the most appropriate strategy to preserve or rehabilitate these structures is to provide some form of a protective coating or barrier. These surface treatments have typically been some form of polymer, asphalt, or low-permeability concrete, but the application of UHPC has shown promise for this application mainly due to its negligible permeability, but also as a result of its excellent mechanical properties, self-consolidating nature, rapid gain strength, and minimal creep and shrinkage characteristics. However, for widespread acceptance, durability and performance of the composite system must be fully understood, specifically the bond between UHPC and NSC often used in bridge decks. It is essential that the bond offers enough strength to resist the stress due to mechanical loading or thermal effects, while also maintaining an extended service-life performance. This report attempts to assess the bond strength between UHPC and NSC under different loading configurations. Different variables, such as roughness degree of the concrete substrates, age of bond, exposure to freeze-thaw cycles and wetting conditions of the concrete substrate, were included in this study. The combination of splitting tensile test with 0, 300, 600 and 900 freeze-thaw cycles was carried out to assess the bond performance under severe ambient conditions. The slant-shear test was utilized with different interface angles to provide a wide understanding of the bond performance under different combinations of compression and shear stresses. The pull-off test is the most accepted method to evaluate the bond strength in the field. This test which studies the direct tensile strength of the bond, the most severe loading condition, was used to provide data that can be correlated with the other tests that only can be used in the laboratory. The experimental program showed that the bond performance between UHPC and NSC is successful, as the strength regardless the different degree of roughness of the concrete substrate, the age of the composite specimens, the exposure to freeze-thaw cycles and the different loading configurations, is greater than that of concrete substrate and largely satisfies with ACI 546.3R-06.

Specifications for tar concrete surface course, coarse open-graded aggregate type, subclass H-3, nonproprietary, cold-lay : effective August 1, 1945.

Reproduced from typewritten copy.

Specifications for bituminous concrete binder and surface courses, coarse dense-graded aggregate type, subclass I-1, nonproprietary, hot-mix : effective April 1, 1945.

Reproduced from typewritten copy.

Specifications for bituminous concrete binder and surface courses, fine dense-graded aggregate type : subclass I-11, nonproprietary hot-mix : effective March 15, 1945.

Reproduced from typewritten copy.

Specifications for bituminous concrete binder and surface courses, fine dense-graded aggregate type : subclass I-11, nonproprietary, hot-mix : effective February 1, 1949.

Mode of access: Internet.

Organizational maintenance repair parts and special tools lists : dryer, aggregate, diesel engine driven, 4 wheel mtd. NSN 3895-00-236-8123 : Barber-Greene MDL DA-60 : components of mixing plant asphalt, 100-150 ton per hour NSN 3895-00-936-8613.

Includes index.

Direct support and general support maintenance repair parts and special tools lists : dryer, aggregate, diesel engine driven, 4 wheel mtd., NSN 3895-00-236-8123, Barber-Greene MDL DA-60 : component of mixing plant asphalt, 100-150 ton per hour, NSN 3895-00-936-8613, Barber-Greene MDL KA-60.

Includes indexes.

Organizational maintenance repair parts and special tools lists : mixer, bituminous material, non-self loading, DED, NSN 3895-00-933-0577, Barber-Greene model KA60, component of mixing plant, asphalt, 100-150 ton per hour, NSN 3895-00-936-8613.

Includes index.

Direct support and general support maintenance repair parts and special tools lists (including depot maintenance repair parts and special tools lists) : mixer, bituminous material, non-self loading, DED, NSN 3895-00-933-0577, Barber-Greene model KA60, component of mixing plant, asphalt 100-150 ton per hour, NSN 3895-00-936-8613.

Includes index.