RELATIONSHIP OF SUPERPAVE GYRATORY COMPACTION PROPERTIES TO HMA RUTTING BEHAVIOR
This report presents the findings of a research project to examine whether there is a relationship between any property of hot mix asphalt (HMA) measurable with the Superpave gyratory compactor and the rutting behavior of HMA pavements in service. Its main finding is that the parameter N-SRmax, the number of gyrations at maximum stress ratio, may be used within certain limits to identify mix designs likely to show gross instability under the shear stresses produced by traffic in HMA pavements. The report will be of particular interest to materials engineers in state highway agencies, as well as to materials suppliers and paving contractor personnel responsible for HMA design and quality control.
Issues Pertaining to Use of Superpave Gyratory Compactor
Agencies, industry, academia, and others are rapidly implementing the products of the asphalt research portion of the Strategic Highway Research Program, products collectively referred to as Superpave. One of the principal products has been the Superpave gyratory compactor (SGC). The results of an experimental program, conducted at the Asphalt Institute Research Center in Lexington, Kentucky, and aimed at assessing the effect of various compaction parameters on SGC test results, are outlined. Compaction results were most often different when different mold diameters were used. The length of the laboratory short-term aging period also affected test results. Compaction temperature was a critical factor when a modified binder was used. SGC affected moisture-susceptibility test results although specimens fabricated using SGC were successfully demonstrated to predict moisture damage using the AASHTO T283 protocol. The experiment also compared the compaction characteristics of several different units. This comparison demonstrated minor to moderate differences in test results when the same mix was evaluated.
Air scrubbing techniques for ammonia and odor reduction at livestock operations : review of on-farm research in the Netherlands
Acid scrubbers and biotrickling filters have been developed for ammonia (NH3) removal at pig and poultry houses 
in The Netherlands over the last 20 years to prevent acidification and eutrophication of soils. Because of growing 
suburbanization, odor removal is increasingly considered important as well. In this review, we report the results of the on-farm 
research on full-scale operated scrubbers for treatment of exhaust air from animal houses with regard to NH3 and odor 
removal in The Netherlands. The NH3 removal of acid scrubbers ranged from 40% to 100% with an overall average of 96%. 
The NH3 removal of biotrickling filters ranged from -8% to +100% with an overall average of 70%. Minimum empty bed air 
residence times (EBRTs) were 0.4 to 1.1 s. For acid scrubbers, process control with pH measurement and automatic water 
discharge is sufficient to guarantee sufficient NH3 removal. For biotrickling filters, however, improvement of process control 
is necessary to guarantee sufficient NH3 removal. The odor removal of acid scrubbers ranged from 3% to 51% with an overall 
average of 27%. The odor removal of biotrickling filters ranged from -29% to +87% with an overall average of 51%. 
Minimum EBRTs were 0.5 to 2.3 s. Further research is necessary to explain this variation and to improve the odor removal 
efficiency of both acid scrubbers and biotrickling filters.