This report presents information on the characterization of cementitiously stabilized layers and the properties that influence pavement performance. It also contains recommended performance-related procedures for characterizing these layers and performance-prediction models for incorporation into the mechanistic–empirical pavement analysis methods. Individual chapters highlight pavement distresses of hot-mix asphalt pavements and concrete pavements, laboratory tests and model development, and model calibration. The material contained in the report will be of immediate interest to state materials, pavement, and construction engineers and others involved in the different aspects of pavement design and construction.

Characterization of Cementitiously Stabilized Layers for Use in Pavement Design and Analysis

In recent years, efforts have been made to incorporate reclaimed asphalt pavement (RAP) into pavement base or subbase applications by means of cement binder stabilization. This approach, however, may not be an environmentally friendly solution due to the high carbon footprint involved in the production of Portland cement. Recycled concrete aggregate (RCA), on the other hand, has been widely accepted in pavement applications. The sustainable solution of blending RAP with RCA was investigated in this research in an attempt to facilitate the usage of this blend as an alternative pavement subbase material. An extensive suite of geotechnical laboratory tests was undertaken on RAP with contents of 100, 50, 30 and 15% in blends with RCA. Results of the research study indicated that RAP/RCA blends with a low 15% RAP content meet the repeated load triaxial requirements for use in pavement subbase layers. Results of field performance of a pavement subbase constructed with untreated 100% RAP, at a private haul road field-demonstration site, confirmed that it had insufficient strength requirements to meet local road-authority pavement-subbase requirements. RAP and RAP/RCA blends, although found in this study to be not fully compliant with the local road-authorities requirements, could be potentially considered for lower traffic usage, such as haul roads and footpaths.

https://researchbank.swinburne.edu.au/file/73bec40c-db31-4728-ac16-60b9f257fe7d/1/PDF (Accepted manuscript).pdf

Reclaimed Asphalt Pavement and Recycled Concrete Aggregate Blends in Pavement Subbases: Laboratory and Field Evaluation

The suitability of crushed concrete or recycled concrete aggregate (RCA) materials has been evaluated for use as pavement material for unbound basecourses. This paper covers the general engineering properties and response to cyclic loading as determined by repeated load triaxial testing (RLTT). In Australia, pavements commonly consist of granular basecourses and subbases supporting thin bituminous seals (asphalt or spray—chip seal). In this paper, a study is presented of the performances of three South Australian basecourse products, nominally 20 mm. The basecourse products included two RCA materials and a local virgin aggregate (quartzite). The resilient modulus and permanent deformation behaviour of RCA mixtures were investigated at different levels of moisture contents (90, 80, and 60% of optimum moisture content), subjected to a simplified stress regime suited to Australian construction. In terms of both resilient modulus and accumulation of permanent deformation, the RCA material performed be...

Properties of Recycled Concrete Aggregate for Unbound Pavement Construction

Potential use of reclaimed asphalt pavement and recycled concrete aggregate in base/subbase layers of flexible pavements

One of the applications of recycled aggregates from construction and demolition processes is the construction of embankments, subbases and foundations for roads where unbound materials are used in replacement for natural aggregates. This work focuses on studying the development of the stiffness of recycled materials during construction, as well as how it modifies over time. The study assessed also the correlation between testing systems. A purpose-built experimental embankment with four sections of different recycled materials was built and tested. Fields were made from two structural layers, forming a homogenous thickness of about 80 cm. The compaction and testing took place using the Continuous Compaction Control technique, obtaining bearing capacity records during the embankment construction phases. The structural performance of the embankment was also determined using different types of light-weight deflectometers. The results show that recycled aggregates perform well when properly compacted and may ...

Construction and demolition waste recycling: an application for road construction

The purpose of this research was to characterize both demolition and haul-back sources of recycled concrete material (RCM) available in Utah County, Utah, for use as pavement base material and to investigate the self-cementing behaviors of each. A telephone survey was conducted to assess the state of the practice with respect to the local use of RCM, and extensive laboratory testing was performed to evaluate the strength and durability properties of both sources of RCM. Laboratory testing included determinations of particle-size distributions, Atterberg limits, specific gravity values, absorption characteristics, moisture-density relationships, California bearing ratio (CBR), unconfined compressive strength (UCS), stiffness, resistance to freeze-thaw cycling, tube suction test (TST) moisture susceptibility classifications, and Los Angeles abrasion losses. The results of the testing indicate that marked stiffening and strength gain of the materials occur within a 7-day curing period, although the rate and ...

Laboratory Characterization of Recycled Concrete for Use as Pavement Base Material

To avoid early-age damage to cement-treated base (CTB) materials, the cement must be allowed to cure before the pavement can be opened to traffic. The purpose of this research was to evaluate the utilities of the soil stiffness gauge (SSG), the heavy Clegg impact soil tester (CIST), the dynamic cone penetrometer, and the falling weight deflectometer for assessing early-age strength gain of cement-stabilized materials. Experiments were performed at four sites on a pavement reconstruction project along I-84 in Morgan, Utah, where cement stabilization was used in conjunction with full-depth recycling. Each site was stationed to facilitate repeated measurements at the same locations with different devices and at different curing times. Because of the considerable attention from the pavement construction industry for routine quality control and quality assurance programs, the SSG and CIST were the primary focus of the research. Statistical techniques were used to evaluate the repeatability of these devices and...

Early-Age Strength Assessment of Cement-Treated Base Material:

CHARACTERIZATION OF RECYCLED CONCRETE FOR USE AS PAVEMENT BASE MATERIAL Brandon James Blankenagel Department of Civil and Environmental Engineering

/pdf/characterization-of-recycled-concrete-for-use-as-pavement-1l1ji3i786.pdf

Characterization of Recycled Concrete for use as Pavement Base Material

Highway 191 near Bluff, Utah, features a well-monitored section of the long-term pavement performance (LTPP) program. Constructed in 1980, this section of flexible pavement performed well for nearly 13 years. Through this time, cracking of the asphalt layer was minimal. In the fourteenth year, however, the extent of longitudinal cracking in the wheel path increased and necessitated placement of a chip seal on the pavement surface. The purpose of this research was to determine the cause of pavement deterioration using LTPP data. Deflection basins obtained from falling-weight deflectometer testing were analyzed to investigate the extent to which structural degradation influenced deterioration of the pavement. Pavement layer modulus values were plotted against time and clearly show that weakening of the pavement base layer immediately preceded the occurrence of cracking. The geography of the site, as documented in photographs, supports the conclusion that inadequate water drainage at the site permitted saturation of the aggregate base layer during a period of midsummer flooding. This finding emphasizes the importance of specifying non-moisture-susceptible base materials and providing necessary drainage works in pavement design.

Brandon J. Blankenagel

Papers

Laboratory Characterization of Recycled Concrete for Use as Pavement Base Material

Early-Age Strength Assessment of Cement-Treated Base Material:

Characterization of Recycled Concrete for use as Pavement Base Material

Deterioration of Asphalt Pavement at Long-Term Pavement Performance Program Site 49-1001 in Utah