Recycled Materials Resource Center

Formation of the atherosclerotic intima must involve altered metabolism of the elastin-rich arterial extracellular matrix. Proteases potentially involved in these processes remain unclear. This study examined the expression of the potent elastases cathepsins S and K in human atheroma. Normal arteries contained little or no cathepsin K or S. In contrast, macrophages in atheroma contained abundant immunoreactive cathepsins K and S. Intimal smooth muscle cells (SMC), especially cells appearing to traverse the internal elastic laminae, also contained these enzymes. Extracts of atheromatous tissues had approximately twofold greater elastase-specific activity than extracts of uninvolved arteries, mostly due to cysteine proteases. Cultured human SMC displayed no immunoreactive cathepsins K and S and exhibited little or no elastolytic activity when incubated with insoluble elastin. SMC stimulated with the atheroma-associated cytokines IL-1beta or IFN-gamma secreted active cathepsin S and degraded substantial insoluble elastin (15-20 microg/10(6) cells/24 h). A selective inhibitor of cathepsin S blocked > 80% of this elastolytic activity. The presence of cathepsins K and S at sites of vascular matrix remodeling and the ability of SMC and macrophages to use these enzymes to degrade elastin supports a role for elastolytic cathepsins in vessel wall remodeling and identifies novel therapeutic targets in regulating plaque stability.

ABSTRACT: Large-scale experiments with cyclic loading were conducted to determine how incorporation of high-density polyethylene (HDPE) geocells affects the rutting properties of working platforms and resilient properties of a subbase in a pavement structure over soft subgrades. Four different geocells were used in this study to reinforce common subbase/base course gravel. Experiments were performed with 225 mm and 450 mm thick unreinforced and reinforced gravel and a crushed rock that is typically used for conventional cut-and-fill working platforms. Experiments were conducted to simulate loading conditions both during construction due to construction equipment and after construction due to traffic conditions over the asphalt pavement once the pavement structure is constructed. Materials used in this study were compacted to 90% relative compaction based on standard Proctor to determine the effect of geocells specifically with gravel material that is compacted to lower than typical standards. Deflections, modulus of subgrade reaction and resilient modulus of each section were evaluated. In summary, presence of geocells reduced the plastic deflection of the working platforms by 30–50%, improved the resilient modulus of the subbase by 40–50%, and the modulus of subgrade reaction by more than 2 times.

The benefits of using recycled materials in highway pavements was assessed quantitatively by conducting life-cycle analysis and life-cycle cost analysis on pavements consisting of conventional and recycled materials for a highway construction project in Wisconsin. Results of the analysis indicate that using recycled materials in the base and subbase layers of a pavement can result in reductions in global warming potential (20%), energy consumption (16%), water consumption (11%), and hazardous waste generation (11%) while also extending the service life of the pavement. In addition, using recycled materials in the base and subbase layers can result in a life-cycle cost savings of 21%. The savings are even greater if landfill avoidance costs are considered for the recycled materials incorporated in the pavement. Extrapolation of the benefits to conditions nationwide indicates that modest changes in pavement design to incorporate recycled materials can contribute substantially to the emission reductions required to stabilize greenhouse gas emissions at current levels.

Compressibility of recycled materials including bottom ash (BA), foundry slag (FSG), foundry sand (FSD), recycled asphalt pavement (RAP), recycled pavement material (RPM), recycled concrete aggregate (RCA), and recycled asphalt shingle (RAS) mixed with glacial outwash sand (GOS) was evaluated using one-dimensional (1D) compression tests. Results showed that except RCA, compressibility of all the compacted recycled materials is higher than that of the compacted GOS. Different compression mechanisms were attributed to each recycled material depending on the type, composition, and morphological characteristics of the particles. Bituminous recycled materials including RAP, RPM, and RAS-GOS mixtures exhibited relatively higher compressibility compared with nonbituminous recycled materials. At a constant vertical effective stress (σv′), compression of the recycled materials increased over time with strain rates that are higher for bituminous recycled materials compared to nonbituminous recycled materials. The vertical strain rates (ε˙v) of all the recycled materials log-linearly increased with increasing σv′. The slope of the logε˙v−logσv′ curves, termed stress coefficient of compression, is independent of the elapsed time after loading. The stress coefficient of compression indicates degree of stress dependency for compression and is different for each recycled material. Secondary compression ratio is a power function of σv′ indicating that an embankment constructed with recycled materials settles at different rates along the embankment height. Temperature rises increased compressibility of the compacted RAP and RAS-GOS mixtures. On the other hand, thermal preloading significantly reduced the compressibility of the compacted RAP and RAS-GOS mixtures. Construction of embankments containing bituminous materials such as RAP, RPM, or RAS is recommended during summer to induce thermal preloading and reduce long-term settlement. Long-term settlements of typical highway embankments constructed with the recycled materials used in this study were below the allowable limit.

Flexural and resilient properties (flexural strength, flexural modulus, fatigue cracking, and resilient modulus) of common cementitiously stabilised materials (CSMs) in pavement systems are presented in this paper. These properties are critical parameters for pavement analysis to determine stress/strain and thus, pavement performance prediction. Four materials (sand, gravel, silt, and clay) and four binders (cement, lime, class C fly ash, and a combination of lime and class F fly ash) were studied. Beam and cylindrical specimens were prepared to study the flexural and resilient properties, respectively. The effect of compaction, binder content, and curing time was evaluated. Modulus growth tests were conducted at 28, 56, 90, 120, 150, and 180 d. A power relationship (R2 = 0.92) between flexural strength and unconfined compressive strength (UCS) for the CSMs was observed. The flexural strength test adopted here was found to be applicable for the whole range of CSMs – both heavily and lightly stabilised soils. The results indicate that determination of flexural modulus is strongest at a stress level of 30%. The number of cycles to achieve a 50% reduction from initial modulus could be considered to define fatigue failure if the specimen does not fail within 8 h.

The effect of temperature on plastic strain and resilient modulus (MR) of different sources of recycled asphalt pavement (RAP) and recycled concrete aggregate (RCA) was evaluated from the results of laboratory temperature-controlled MR tests, with a conventional Class 5 aggregate serving as the control. Freeze–thaw tests were also conducted on samples of RAP and RCA. Five years (spring–summer–fall–winter) of field falling weight deflectometer (FWD) tests were conducted on three pavement sections with RAP, RCA, and Class 5 as the unbound base course. Laboratory test results showed that temperature rise increased plastic strain and reduced MR of RAP under cyclic loads but had a negligible effect on plastic strain and MR of RCA. Freeze–thaw cycles steadily reduced the MR of RAP; however, long-term freeze–thaw cycles increased the MR of RCA. Thermal preloading reduced the plastic strain and increased the MR of the compacted RAP. Construction of a pavement system made with RAP is thus recommended during warm seasons to induce thermal preloading. The elastic modulus back-calculated from the FWD tests did not show a consistent trend with respect to temperature change. No significant change on elastic modulus of RAP, RCA, and Class 5 aggregates due to freeze–thaw cycles was observed over five years.

The most common recycled construction materials used as unbound base course in pavement construction are recycled concrete aggregate (RCA) and recycled asphalt pavement (RAP). This study investigated the mechanical properties of RCA and RAP as unbound base, including the relationships between resilient modulus (Mr) and composition (e.g., particle shape, binder type, aggregate mineralogy, and contamination). The recycled materials were collected from a wide geographical area, covering eight states in the U.S. The Mr tests were conducted following National Cooperative Highway Research Program (NCHRP) protocol, which measures specimen deflections externally and internally. Power function and NCHRP models were applied to estimate Mr. The NCHRP model was more reliable in capturing Mr dependency on stress state in RCA and RAP. A multiple linear regression model was developed to predict the Mr of RCA (R2=0.96) and RAP (R2=0.97). There was a high degree of correlation between the predicted Mr and the physical properties of RCA (R2=0.89) and RAP (R2=0.99).

Abstract In this study, a testing protocol was developed to measure the flexural strength, flexural modulus, and fatigue failure of cementitiously stabilized materials (CSMs) for both lightly and heavily stabilized soils. Four soils (sand, gravel, silt, and clay) and four binders (cement, lime, class C fly ash, and class F fly ash) were used in this study. Beam specimens (100 mm high by 100 mm wide by 400 mm long) were prepared and tested using third-point flexural beam tests. A fatigue distress model was developed, and the data from this study was validated using other existing stress-based fatigue models. Results indicated that the testing protocol could be used to determine the flexural strength, flexural modulus, and fatigue behavior of the cementitiously stabilized layers (CSL). A stress-based fatigue performance model was a good fit for the whole range of CSMs, which is needed to predict the fatigue performance of CSL in the field and to determine the fatigue life of the CSLs.

The use of recycled materials in highway construction can achieve significant benefits affecting the triple bottom line (environment, prosperity, and society). Although state departments of transportation have been at the forefront of introducing recycled materials, they have been unable to clearly convey the benefits in a quantitative and transparent manner using easily understood metrics. Information on sustainability assessment characteristics—that is, energy and water consumption—is lacking. To determine the benefits of using recycled materials for six member state departments of transportation in a pooled fund, the Recycled Materials Resource Center at the University of Wisconsin–Madison was tasked with a project that would quantify the environmental and economic life-cycle benefits associated with the incorporation of recycled materials and industrial by-products in highway construction. An analysis of the environmental benefits (i.e., carbon dioxide emissions, energy consumption, and water consumption) associated with the substitution of recycled materials for conventional virgin materials in highway construction was conducted using the pavement life-cycle assessment tool for environmental and economic effects, a tool developed with the sponsorship of the Recycled Materials Resource Center. An economic impact analysis was conducted by comparing the unit prices of virgin and recycled materials. The analysis showed significant environmental and economic savings in all member states. Total environmental savings from use of recycled materials were approximately equal to the energy consumption of 110,000 U.S. households per year, 9,300 bathtubs of water, and the carbon dioxide emissions produced by 58,000 cars per year. Total systemwide economic savings from use of recycled materials was estimated to be $62.5 million.

The Building Environmentally and Economically Sustainable Transportation-Infrastructure-Highways (BE 2 ST-in-Highways) sustainability rating system was developed to provide a quantitative methodology for rating the benefits of sustainable highway construction. The methodology is grounded in quantitative metrics so that a transparent linkage exists between the project rating and the sustainable practices employed in design and construction. This rating system can be employed by the highway construction industry and agencies to evaluate sustainable practices quantitatively and to incorporate sustainable elements into projects. To illustrate how BE 2 ST-in-Highways is employed, 10 alternative designs were evaluated and compared with two reference pavement designs for a pilot project (Baraboo Bypass, Wisconsin). The results of this pilot project evaluation indicate that the use of recycled materials instead of conventional materials in highway construction can improve sustainability considerably: about 27% reduction in global warming potential and energy and water use. Reductions in carbon dioxide emissions and energy and water consumption are largely due to the reduction of the material production phase (e.g., mining and processing) by substituting existing recycled materials and reducing the thickness of the base layer and the number of rehabilitation events due to longer service life because of superior properties. Use of recycled material resulted in reductions in the life-cycle cost by as much as 30%. Using recycled materials in the surface layer is not the use with the highest value. Using recycled materials in the base course is thus more advantageous and has higher value because larger material quantities are involved in the base course with greater potential for cost savings, as shown in this case study.

The conventional highway resurfacing technique of mill and overlay (M&O) partially removes the existing pavement and replaces it with asphalt derived from some recycled but mostly virgin materials. Cold-in-place recycling (CIR) is an alternative highway resurfacing method that partially mills the existing pavement and uses it beneath a thinner layer of new asphalt. CIR has become widely used for convenience and cost benefits, but the environmental impacts are poorly quantified. The objective of this study was to quantify the environmental life cycle benefits of using CIR for highway resurfacing instead of M&O. Material quantities and equipment used for CIR and what would have been used in M&O for the same project were provided by contractors for nine highway resurfacing projects in Wisconsin. With this information, a life cycle assessment (LCA) tool was used to determine the relative environmental impacts of the two methods, with energy consumption, water usage, and carbon dioxide emissions chosen as the metrics of the LCA. Results show average environmental savings of 23% in energy consumption and carbon dioxide emissions and 20% in water consumption when using CIR instead of M&O for highway resurfacing. Additionally, CIR reduced virgin aggregate consumption by 37%. Environmental savings achieved by using CIR were found to be directly related to the reduction in volume of new hot mix asphalt (HMA) used, and to the reduction in transportation of materials to and from the site. Linear correlations that can be used to estimate savings of future CIR projects were projected.

Aims principally to identify the main issues relating to the strategic impact and application of total quality management (TQM). Uses a grounded theory inductive research methodology involving 19 case study organisations. In this approach, the deep rich data gained through the dialogue and story telling, is critical to the research study findings. Therefore, the findings are presented largely in the form of transcript quotes and coding analysis. Furthermore, the grounded theory approach enables simple constructs to be created and developed throughout the research discourse. The findings indicate that largely bureaucratic approaches to TQM and strategy exist without proper integration of employee and customer feedback. TQM mainly impacted the strategy process at the objective setting level, forming a strategic‐operational divide, reflecting a tactical emphasis for TQM deployment. Thus, there is a need for TQM to be considered from a philosophical level rather than simply as an operational tool. A considerable gap was found to exist between organisational rhetoric, in relation to strategy and TQM, in comparison to organisational practice.

Effectiveness of cement kiln dust (CKD) in improving the stiffness of recycled base course materials was studied using both seismic modulus and bench-scale resilient modulus tests. Recycled materials included road surface gravel (RSG) and recycled pavement material (RPM). The modulus of RPM and RSG specimens mixed with CKD increased 5–30 times compared with untreated materials; however, the improvement was not as high as cement stabilization. Modulus generally increased with curing time with more hydration; however, decrease in the modulus of the RPM mixed with 15% CKD during curing is attributed to swelling potential of the CKD. Lower rate of increase in modulus of CKD mixtures compared with cement mixtures with curing time was attributable to the chemical composition of CKD, i.e., high free lime and sulfate contents. Freeze-thaw durability tests resulted in modulus reduction on the order of 0.5 to 0.8 for CKD mixtures and 0.5 for cement mixtures. Attributable to the combined effects of stiffness gain with continuing hydration and stiffness reduction with freeze-thaw cycles, the final modulus of the recycled materials mixed with CKD is 2 to 5 times higher than that of untreated RPM and RSG materials. This study also showed that modulus change of stabilized granular materials can be estimated from seismic Young’s modulus.

This paper describes a green highway construction rating system named Building Environmentally and Economically Sustainable Transportation Infrastructure-Highways (BE2ST in-Highways). BE2ST in-Highways employs life cycle analysis techniques to provide a quantitative assessment of the impacts associated with a highway construction project. Energy and water consumption, greenhouse gas emissions, service life, and life cycle cost are evaluated in a quantitative framework that can be used to compare alternative construction strategies from a holistic perspective. The methodology is grounded in quantitative metrics rather than an arbitrary point system so that a transparent linkage exists between the project rating and the sustainable practices employed in design and construction. This transparency reduces the potential for `gaming' of the rating system. Application of the BE2ST in-Highways system to a project in Wisconsin is described. Results of the application indicate that using recycled materials in a pavement can result in reductions in global warming potential (32%), energy consumption (28%), water consumption (29%), and hazardous waste generation (25%) as compared to the reference design using conventional materials, while also extending the service life of the pavement. In addition, using recycled materials in a pavement can result in a life cycle cost savings of 23%. Because of this environmental and economical outperformance of the alternative design using recycled materials compared to the reference design using conventional materials, the maximum total credit (i.e., 12 points) is granted to the project.

Life cycle assessments of recycled material use in roadways are currently not well understood or well documented. The Recycled Materials Resource Center’s (RMRC) research is aimed at quantitatively determining the environmental and economic benefits of using recycled material in road construction. Two case studies were performed to analyze the impacts of incorporating recycled material in the reconstruction of two major roadways using life cycle assessment (LCA) and life cycle cost analysis (LCCA) tools. Results from both roads show that the use of recycled materials reduces energy and water consumption, greenhouse gas emissions, and cost. Because typical roadway construction projects do not separately track the extensive use of recycled materials, the RMRC was unable to utilize the LCA and LCCA technology in the first roadway’s analysis without making significant assumptions for the inputs. To clarify and verify some of these assumptions, the second roadway project was undertaken. This second case study is being studied to determine a better methodology for data collection with fewer assumptions, in addition to assessing the benefits of recycled material use. The methodology for data collection and analysis developed through the second project can be used to conduct LCAs and LCCA for future highway construction projects with greater confidence.

Leaching of four trace elements [cadmium (Cd), chromium (Cr), selenium (Se), and silver (Ag)] from soft organic soils stabilized with high carbon fly ashes (HCFAs) was assessed using water leach tests (WLTs) and column leach tests (CLTs) on soil alone, fly ash alone, and soil-fly ash mixtures. Concentrations from the WLTs on soil-fly ash mixtures were lower than concentrations from the WLTs on fly ash alone, and were controlled more by the fly ash than the soil. However, dilution calculations based on tests on soil alone and fly ash alone were unreliable. Thus, leaching assessments should be conducted directly on soil-fly ash mixtures. Leaching patterns from the CLTs followed first-flush and lagged-response patterns with comparable frequency, although first-flush patterns were more common with fly ash with higher calcium oxide content. Cd and Cr exhibited first-flush leaching more frequently, Ag a lagged-response pattern more frequently, and Se exhibited first-flush or lagged-response patterns with similar frequency. The hydrogen ion concentration (pH) had a strong effect on leaching concentrations, with lower concentrations of Ag and Cd and higher concentrations of Cr at a higher pH. Peak concentrations of Ag and Cd for flow-through conditions can conservatively be estimated as 50 times the WLT concentration, whereas a factor of 100 should be applied for Cr and Se for organic soil-HCFA mixtures.

Use of recycled materials promotes sustainability in geotechnical construction. Compaction characteristics, hydraulic conductivity, shear strength, and compressibility of bottom ash (BA), foundry slag (FS), recycled asphalt pavement (RAP), and recycled asphalt shingles (RAS) that are produced in large quantities were characterized. Results showed that BA, FS, and RAS have lower maximum dry unit weight than compacted sand and the dry unit weights are not sensitive to compaction moisture content. Shear strength of the tested recycled materials are adequate to provide stability for typical highway embankments. The measured hydraulic conductivities provide sufficient drainage capacity for embankment fills. Results of one-dimensional compression tests showed that BA and FS have comparable compressibility to that of compacted sand up to vertical effective stress (σ'v) of 200 kPa after which BA and FS exhibited higher compressibility than sand due to crushing of individual particles. Compressibility of RAS is significantly higher than that of sand, which makes the material unsuitable as embankment fill. RAP consistently has higher compressibility than sand; however, settlement of typical highway embankments constructed with RAP is still below the typical allowable limit. BA, FS, and RAP have appropriate engineering properties for use as structural fill in typical highway embankments. RAS should be mixed with at least 50% of granular additive to reduce compressibility to an acceptable limit. Construction of embankments with RAS mixture or RAP is recommended during warm seasons to induce thermal preloading and reduce compressibility.

Foundry sand is a high-quality uniform silica sand that is used to make molds and cores for ferrous and nonferrous metal castings. The metal casting industry annually uses an estimated 100 million tons of foundry sand for production. Over time, foundry sands physically degrade until they are no longer suitable for molds. Consequently, 9 to 10 million tons of sand is discarded each year. However, the discarded foundry sands have remarkably consistent composition and are generally considered a higher quality material than typical bank run or natural sands used in construction. Currently, an estimated 28% of discarded foundry sand is reused, primarily in construction-related applications, while the remaining sand is disposed of in landfills (American Foundry Society 2007). Recycling of foundry sand can save energy, reduce the need to mine virgin materials, and may reduce costs for both producers and end users. Use of foundry sand as a fine aggregate in construction applications offers project managers the ability to enhance green sustainable construction by reducing their carbon footprint, while also qualifying for LEED credits. The U. S. Environmental Protection Agency (EPA) recently estimated that at the current recycling level 20,000 tons of CO2 emissions are prevented while 200 billion BTUs of energy are saved (US EPA 2008). Support for increased reuse of foundry sand has brought together the U.S. EPA, the Federal Highway Administration, the U. S. Department of Agriculture, the Recycled Materials Resource Center (RMRC), state environmental agencies, the foundry industry and end users to develop the tools and resources needed to increase foundry sand recycling to 50% by 2015. This paper provides a comprehensive overview of the engineering and construction properties of foundry sand for use in Portland cement concrete, hot mix asphalt, road subbase layers, embankments, and flowable fill. Recent studies addressing environmental concerns of using foundry sand as a construction material are reviewed. With the goal of advancing use of foundry sand in construction application, references to resources and tools, such as web-based training and a foundry locator map module, are made available.

Abstract This paper examines the relationship between Total Quality Management (TQM) and Corporate Strategy by investigating the strategic impact of TQM on organizations. There is a paucity of in‐depth research examining this complex relationship. The research methodology is a grounded theory inductive approach involving nineteen case studies. In this approach the dialogue and storytelling within the research study enables key constraints and areas of interest in the TQM/Strategy discourse to emerge. The key findings indicate that: (1) in many cases the bureaucratic/functional approach to strategy is paralleled in the approach to TQM; (2) a number of organizations had difficulty in identifying the ‘driving’ influences of TQM in relation to corporate strategy; (3) TQM is found to be a useful catalyst for developing corporate strategy; (4) some organizations were found to restrict their TQM efforts to operational levels rather than adopting Strategic Total Quality Management. Copyright © 2001 John Wiley & Sons, Ltd.

The light-weight deflectometer presents significant potential for compaction quality control and for determining in situ resilient modulus of pavement layers during construction. Data collected from a laboratory large-scale model experiment and two light-weight deflectometer devices (Keros and Zorn) were used to develop a means of estimating the resilient modulus of various base course materials. The procedure can be used for validating the input parameters in design. Measured surface elastic deflections of a layered pavement system from the LWD devices must be corrected for the effect of subgrade deflection and the differences in the state of stresses. A power function represents the relationship between the corrected elastic deflection from the light-weight deflectometers and the resilient modulus of the base course layer from the large-scale model experiment. This study provides a basis for use of the light-weight deflectometer in estimating as-constructed resilient modulus of a base course layer involving natural and recycled unbound materials as well as fly ash stabilised materials.