Sustainable Pavement Maintenance Practices (2011)

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to maintenance but rather to construction or planning of pavements. A closer look at some of those programs shows that the agency-wide program is focused on sustainable design and construction with little specific guidance being given to environmental sustainability within pavement preservation and maintenance. This leads to the identification of a need for future efforts to develop the programmatic guidelines and specifica- tions needed to implement sustainable pavement preservation and maintenance programs. Summary Although agencies are becoming more aware of the significance of the concept of environmental sus- tainability, this does not translate to direct measures for use within their maintenance programs. More than 80% of responding agencies indicated that their agency did not use environmental performance, nor did they have agency-wide environmental sustain- ability or sustainable maintenance specifications. Conclusions The following conclusion was reached in this chapter: • Environmental sustainability research that is related specifically to post-construction oper- ations is an emerging field. Future Research Needs The following research needs were identified in this chapter: • There is a need for pavement preservation and maintenance-specific research to furnish agency pavement maintenance engineers with the fundamental data on the relative environ- mental sustainability of common treatments. • There is a need to develop a pavement preser- vation and maintenance-specific life-cycle assessment and cost analysis method that includes values for factors such as carbon sequestration, resource renewability, and other salient elements of environmental sustainabil- ity to furnish a rational approach to treatment selection. QUANTIFYING ENVIRONMENTAL SUSTAINABILITY IN PAVEMENT PRESERVATION AND MAINTENANCE Introduction This chapter presents the seven environmental sustainability impact factor areas and the extent to which the survey responses used them in their con- struction and maintenance decisions. Environmental stewardship considers the use of renewable resources at below their rates of regeneration and nonrenewable resources below rates of development of substitutes as noted by the first two environmental sustainability impact factor areas. In addition, the need to provide a clean environment from both an air quality and water quality perspective could be included in an environ- mental monitoring plan, as well as including pollution prevention, climate protection, habitat preservation and aesthetics (Ramani et al. 2009). 10 Table 3 Summary responses to environmental and sustainability programmatic questions No Yes No Yes No Yes No Yes Canada 7 0 5 2 7 0 7 0 U.S. 40 2 38 4 41 1 36 6 Total 47 2 43 6 48 1 43 6 Percentage 96% 4% 88% 12% 98% 2% 88% 12% PMS = Pavement Management System. Does your agency use environmental performance to select maintenance and/or preservation program practices? Do you have an agency-wide “sustainability” program that includes pavement maintenance activities? Does your agency have sustainable maintenance specifications? Does your agency use PMS software to monitor environmental performance

Recycling, reusing, and reclaiming of existing materials is crucial to advance sustainable develop- ment (Carpenter and Gardner 2007). Construction materials can be expensive and now some resources are in limited supply, making it important to make good use of available materials. One of the concerns with the use of recycled material is potential uncer- tainty regarding the actual composition of a recycled material when compared with the virgin material it would replace. As a result, some agencies have with- held permission to use recycled materials, whereas others have limited the amount of recycled material that can be incorporated into the pavement structure (Melton and Morgan 1996; Smith and Romine 2009). Several successful uses of recycled asphalt pavement and recycled concrete aggregate are available in the literature and it can be noted that in addition to pro- viding technical benefits, they improve the perfor- mance of the pavement (Beatty et al. 2002; Alkins et al. 2008; Tighe et al. 2008; Smith and Tighe 2009; Scholz 2010). Further, both hot and cold in-place recy- cling are used by agencies for maintenance and reha- bilitation of pavements, minimizing the amount of new materials for the work and reducing energy requirements for transporting materials to the job site. Table 4 shows that roughly 70% of the responding agencies permit the use of recycled materials in their pavement preservation and maintenance programs. Alternative materials also hold the promise of being able to enhance environmental sustainability in pavement preservation and maintenance. Research has shown that materials such as recycled asphalt shingles, recycled rubber tire, recycled glass, and reclaimed carbon from copier toner can be success- fully incorporated into new pavements (Chan and Tighe 2010). The incorporation of innovative materi- als can also potentially enhance pavement perfor- mance and reduce the demand for virgin materials (Horvath 2004). Thus, the survey sought to find the level of alternative material usage in agency pavement preservation and maintenance programs in Canada and the United States. Table 5 shows that alternative materials have a lower level of use than recycled materials, probably awaiting further research into their long-term performance in maintenance applica- tions. Table 5 reflects the relatively widespread use of fly ash in concrete, as well as asphalt shingles and recycled rubber tires in hot-mix asphalt pavements. However, the use of other alternative materials remains relatively uncommon. These results suggest that future research into applications and performance of alternative materials could be of value. Minimizing or eliminating noise pollution is another element of a sustainable design and con- struction program, and it follows that standards imposed on construction may also be applicable to maintenance operations. Table 6 shows the results of that portion of the survey. Only about 21% of the respondents believed that noise pollution is an impor- tant/very important issue in their agencies. Only 7% were aware of noise standards for their agencies’ pavement maintenance operations, whereas more than one-third of the survey respondents did not have any noise standards for maintenance operations. Relevant future research could help establish appropriate noise standards for construction and maintenance opera- tions, and provide a tool for using noise considerations as part of treatment selection. As noted by the high number of respondents choosing the “no opinion” or “don’t know” categories, it could be suggested that education and training be provided in this environ- mental sustainability impact factor area for mainte- nance personnel. For the environmental sustainability factor of water quality, there is a similar unfamiliarity among the survey respondents about how agency policies are applied to maintenance activities. Based on this eval- uation, there are no current measures available that 11 Table 4 Summary of recycled and alternative materials authorization Are Recycled Materials Allowed Are Alternative Materials Allowed in Your Current Program? in Your Current Program? No Yes No Yes Canada 0 7 2 5 U.S. 14 28 18 24 Total 14 35 20 29 Percentage 28.6 71.4 40.8 59.2

quantify the effects of pavement maintenance and preservation on water quality. The data indicate that the pavement preservation and maintenance treat- ment’s impact on water quality is considered less than half the time, probably because less than half the responding agencies indicated that they have agency water quality guidelines. That roughly one-third of all respondents did not know if their agency consid- ered water quality or had water quality guidelines indicates that coupling programmatic environmental sustainability with pavement preservation and main- tenance programs has not yet happened in North America. Again, this would reinforce the need to develop measures in this area for quantification. The news with regard to air quality is better. A little over 60% of the agencies reported that they monitor air quality in the course of their pavement maintenance operations. However, only 25% of 12 Table 6 Summary of noise pollution measures Canada 0 1 3 0 2 1 2 1 0 4 0 U.S. 4 4 12 0 4 11 7 2 3 11 15 Total 4 5 15 0 6 12 9 3 3 15 15 Percentage 9.5 11.9 35.7 0.0 14.3 28.6 21.4 7.1 7.1 35.7 35.7 How important is noise distribution during pavement maintenance operations in your agency? Agency Noise Standards in Effect V er y Im po rt an t Im po rt an t N eu tr al N ot Im po rt an t N ot E ve n C on sid er ed N o O pi ni on C on st ru ct io n N oi se M ai nt en an ce N oi se Tr af fic N oi se N o N oi se S ta nd ar d D on ’t K no w TABLE 5 Summary of recycled and alternative material usage by pavement type Recycled/Alternative Gravel Surface Treated Asphalt Material Canada U.S. Canada U.S. Canada U.S. Fly Ash 0 0 0 1 1 0 Shingles 0 1 0 1 2 13 Tire Rubber 0 1 0 1 2 13 Glass 0 2 0 0 0 3 Foundry Sand 0 0 0 0 0 1 Carbon 0 0 0 0 0 1 Recycled/Alternative Concrete Composite Material Canada U.S. Canada U.S. Total Percentage Fly Ash 4 21 0 1 28 57.1 Shingles 0 0 0 0 17 34.7 Tire Rubber 0 0 0 0 17 34.7 Glass 0 1 0 0 6 12.2 Foundry Sand 0 2 0 0 3 6.1 Carbon 0 0 0 0 1 2.0