Statistics for Superpave Hot-Mix Asphalt Construction Quality Control/Quality Assurance Data

2002 ◽  
Vol 1813 (1) ◽  
pp. 151-156 ◽  
Author(s):  
Frazier Parker ◽  
M. Shabbir Hossain
Author(s):  
Robert L. Schmitt ◽  
Jeffrey S. Russell ◽  
Awad S. Hanna ◽  
Hussain U. Bahia ◽  
Galadriel A. Jung

State highway agencies and contractors have been implementing quality control/quality assurance (QC/QA) specifications in recent years to advance the quality of hot-mix asphalt (HMA) construction. During their continued development, attributes of these QC/QA specifications have varied among states. The objective of this paper is to provide a compilation of state-of-the-practice in QC/QA for HMA construction and provide recommendations for state highway agencies and contractors when modifying or developing a QC/QA specification. Survey data from 42 state highway agencies and 61 contractors working within 14 states found that a majority of states are using contractor data for acceptance. A review of QC/QA specifications from 40 states found that most states are using plant-produced mix properties, density, and smoothness tests to determine overall quality and acceptance of HMA construction work. A larger number of states are using quality level analysis for specification compliance by estimating percent within limits or percent defective for mix properties and density. Consideration is given to key attributes of a QC/QA specification, including ( a) whether to use contractor or agency data for acceptance, ( b) use of quantity or time for lots, and ( c) testing frequency. State highway agencies and contractors may find this report useful for understanding the components of different QC/QA specifications and furnishing essential information as both parties collaborate during specification development.


Author(s):  
Robert P. Elliott ◽  
Yanjun Qiu

A common provision in quality control/quality assurance construction contracts is the adjustment of the contractor's pay on the basis of the quality of the construction. The expected impact of the provision on the pay should be examined to ensure that the adjustments are neither unduly severe nor excessively lenient. Most pay adjustment plans have been developed around a quality index by using a percent defective approach. Analyses of these plans are complex but reasonably well defined. Other plans, however, are more complex and do not lend themselves to direct analysis. These plans can be examined by computer simulation. The use of computer simulation to examine a complex pay adjustment provision is demonstrated. The analyses show that simulation can reveal that a pay adjustment schedule behaves differently than it appears on the surface. For example, the schedule examined bases pay solely on averages and appears to ignore construction variability. The analyses, however, demonstrate that the pay adjustments are at least as sensitive to construction variability as they are to construction averages. It is also shown that the simulation process can provide a better, more detailed examination of the pay schedule than is possible by simply determining the expected pay. In particular, the simulation process can provide an indication of the variability of pay at various quality levels and can identify the factors most responsible for pay adjustments.


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