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26 Quality control is required to ensure desired performance. The following section describes procedures that should be followed to improve the likelihood of good performance for a chip-seal project. 8.1 Aggregate Sieve Analysis Aggregate gradation should be checked whenever there is potential for signiï¬cant variation in the chip gradation. For example, if chips have been stockpiled near the project and there is sufï¬cient quantity to supply the entire project, a com- plete gradation analysis before construction begins, and every 100 tons thereafter, should be adequate. Also, loader opera- tions at the stockpile can produce excess material passing the no. 200 screen and should, therefore, be monitored. Aggregate gradation should not deviate from the target design gradation by more than the following tolerances: Tolerance, Sieve ±, % 3â4 5 1â2 5 3â8 4 No. 4 3 No. 8 1 No. 200 0.5 When chips are supplied from multiple locations, sam- pling and testing for gradation should be done with more frequency, including checking each truck if high variability is suspected. Because a full sieve analysis may not be practical, hand sieving in the ï¬eld using only the coarse aggregate screens can provide information on the suitability of the material or help determine if more laboratory testing is needed. 8.2 Moisture Content of System The moisture content of the chips should be measured at the beginning and the end of the day for (1) calculating aggregate spread rate and (2) determining when sweeping can be done and when trafï¬c control can be removed. Moisture content can be determined by complete moisture evaporation from the chips using a forced draft oven or a microwave oven. By weigh- ing the chips before and after removing moisture, the moisture content (w) can be determined as follows: 8.3 Embedment Depth Measurement During Construction Embedment depth is usually determined during construc- tion by pulling several chips out of the binder and visually esti- mating the amount of embedment. This is difï¬cult and often subjective even if chips have a very low ï¬akiness index. There- fore, a new method is recommended of spreading a volume of 50 cm3 of glass beads over the surface of the embedded chips and measuring the diameter. During the chip-seal design, the relationship between glass bead diameter and aggregate embed- ment is determined. During construction the glass beads are spread on the pavement and the diameter measured. Embed- ment is then determined using the relationship between glass bead diameter and embedment from the design measurements. 8.4 Field Viscosity The viscosity of the emulsion should be checked for each transport load. This can be done in the absence of a ï¬eld lab- oratory using a Wagner ï¬ow cup. Flow times of 20 to 70 s at 85 to 150°F for a 6-mm oriï¬ce or 10 to 60 s at 85 to 140°F for a 7.5-mm oriï¬ce have been found to provide satisfactory ï¬ow rates. If ï¬ow rates using a Wagner cup are not within these limits, the temperature of the emulsion should be checked to determine if emulsion temperature is the cause. If tempera- ture of the emulsion is not causing unacceptable ï¬ow rates, other causes should be investigated. w, wet weight dry weight wet weight % = â Ã100 C H A P T E R 8 Quality Control