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12 to approach chip seal as an art is derived from the uncertain- 30 27 ties and variability that exist with all chip seal projects. There- >50% 25 fore, the experience of the construction crew, familiarity with No. of Responses <50% the local materials, and suitable equipment usage are consid- 20 None 12 ered to be the critical factors for project success. Because the 15 1 variability and uncertainties that affect the chip seals are inde- 8 10 pendent of the design parameters, proponents of chip seal as 4 3 5 0 1 0 an art argue that a formal design procedure is futile. One of the major difficulties involved in the design of material appli- 0 US Canada AU, NZ, UK, cation rates is nonuniformity of the existing pavement sur- SA face. Such conditions necessitate binder rate adjustments in the field at the time of construction, a phenomenon that under- FIGURE 6 Use of in-house resources to complete chip seal mines formal design. This realm of thought contends that if program. chip seal projects require field adjustments to application rates, formal design is simply a tool for estimating quantities. rect. The Texas DOT (TxDOT) study found that definitions for common terms such as "flushing," "bleeding," "ravel- SOUND ENGINEERING PRINCIPLES ing," and "shelling" varied from district to district within that single state (Gransberg et al. 1998). As a result, an engineer Australia, New Zealand, South Africa, and the United King- in one district who defines the condition as one in which the dom have all developed their chips seal programs based on chip seal is losing its aggregate as "raveling" may make a call a greater set of engineering principles than those used by for guidance to another engineer in a district where the con- highway agencies in Canada and the United States. For exam- dition is called "shelling" and the term "raveling" is applied ple, all of the overseas agencies actually measure surface tex- only to hot-mix asphalt pavement distress. Because of the ture using a sand circle test to characterize the existing pave- different local definitions, the first engineer may be given ment surface. In addition, all of the overseas agencies find it incorrect advice on how to rectify the problem. necessary to carry out surface hardness tests by using spe- cialty testing equipment such as a penetrometer or ball pene- This synthesis study expanded its reach beyond the United tration device, to determine the nominal size of the aggregate States and found additional chip seal terminology in Canada, to be used in their advanced design methodologies. The use the United Kingdom, South Africa, Australia, and New of these sound engineering principles reduces the uncertainty Zealand. Thus, an effort was made to assemble a chip seal and variability associated with chip sealing to the point where glossary, which is found following the References. For that field adjustments of binder and aggregate application rates are glossary, chip seal terms were captured from both the litera- minimized. Not only do these sound engineering principles ture search and the survey responses. Definitions were devel- seek to optimize material application rates, but they have fur- oped for each and an attempt was made to correlate those nished a platform on which to develop and enforce specifica- terms that have similar definitions in a manner that allows an tions to an extent where performance-driven contracts trans- easy reference for readers of this report. fer the risk of the project to the contractor (Sprayed Sealing Guide 2004). As such, they have moved the chip seal project This report uses the terminology found in the Strategic from the maintenance world and into the construction con- Highway Research Program's Distress Identification Man- tract arena. Figure 6 shows the survey responses addressing ual for the Long-Term Pavement Performance Project (1993) the issue of using in-house maintenance personnel. It can be to the greatest extent possible to maintain a consistent termi- observed that the majority of the U.S. respondents are per- nology. It is recommended that the reader frequently refer to forming most, if not all, of their chip seal program internally. the glossary to ensure that full understanding of the report's The situation is reversed in Australia, Canada, and New contents and that the reader is not assigning his or her own Zealand, where most of the work is contracted out. local meanings to the terms contained in the report. CHIP SEAL TERMINOLOGY The remaining chapters discuss both the literature review and survey responses in tandem. The objective is to report One of the difficulties in communicating technical matters what was found in the literature and then allow the reader to between highway agencies is the result of the different tech- use the survey results to either confirm or refute the state- nical terms that are inherent to the chip seal process. This is ments in the literature. This method will then be used to dis- further exacerbated because practitioners invariably believe till the overall results of this synthesis into a list of best prac- that the terminology that they use is indeed technically cor- tices for each subject, by chapter.