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10 a power screed, a manual screed, or a static screed. He gives examples of each in his paper. FIGURE 6 Vibrating screed consolidates and strikes off PPC overlay. (Courtesy : Virginia Center for Transportation Innovation and Research.) FIGURE 9 Equipment used to blow aggregates onto overlay surface. QUALITY CONTROL TESTS Quality control tests and required test results according to Sprinkel (15) are as follows: Resin It is important that resin or monomer be sampled at the rate of one sample for each 3,785 L (1,000 gal). The required vis- cosity, gel time, tensile elongation, and bond strength are FIGURE 7 Metered mixing and placement of mixed polyester shown in AASHTO Guide Specifications (6 ) along with the polymer concrete from mobile concrete batching plant. appropriate test method. Samples are to be accepted only (Courtesy : Gomaco.) when the required properties are furnished. The curing time is a function of the type and amount of initiator or curing agent, curing temperature, and binder content. AASHTO Guide Specifications (6 ) show the minimum times for cur- ing that have been successfully used for TPOs. Aggregate An aggregate sample needs to be obtained for each 43,350 kg (100,000 lb) of aggregate used. The aggregate grading can be determined to be acceptable when meeting the grad- ing shown in AASHTO Guide Specifications (6 ). Aggre- gates subject to wear would be silica or basalt and have a Mohs scale hardness of about 7. Typically, DOTs specify noncarbonate aggregates or FIGURE 8 Placement and finishing fresh PPC surface with define aggregates with a specified acid insoluble residue (AI) modified laydown machine and conventional tining rake. minimum that ranges from 80% to 95% for coarse aggregates (Courtesy : Gomaco.) for long-term surface friction. The test method for AI is pro- vided in ASTM D3042-09 Standard Test Method for Insoluble Dimmick (18) describes two methods of mixing and three Residue in Carbonate Aggregates (19). This is the basis for all methods for placing premixed TPOs. He suggests mixing in individual state DOT test methods. AASHTO does not have a containers with electric power drills with paint paddle mix- listing for this test method. Some states, including Missouri, ers or in drum mixers. For placement, he suggests the use of list New York State DOT Method 28 for AI.