Calculating Air Voids at Specified Number of Gyrations in Superpave Gyratory Compactor

1998 ◽  
Vol 1630 (1) ◽  
pp. 117-125 ◽  
Author(s):  
William R. Vavrik ◽  
Samuel H. Carpenter
Keyword(s):  
Quality Control ◽  
Current Method ◽  
Mixture Design ◽  
Calculation Procedure ◽  
Air Voids ◽  
Superpave Gyratory Compactor ◽  
Quality Control Testing ◽  
Field Quality ◽  
Back Calculation ◽  
Air Void

The Superpave volumetric mix design is based on compaction of mixtures to Nmax revolutions, yielding approximately 2 percent air voids, and then back-calculating the properties of the mixture at N design revolutions, which is the specified number of revolutions at which the sample should achieve 4 percent air voids. It has been shown, both in mixture design and in field quality control testing, that this back-calculation procedure is not always accurate for determining the number of gyrations that give 4 percent air voids in the compacted sample. The current back-calculation procedure is examined in this paper, and the observed inaccuracy in the current method is shown in both quality control/quality assurance (QC/QA) and the mixture design procedures. Also examined is an alternative method that has been shown to be more accurate in predicting the number of gyrations at which a mixture reaches a given air void level. This study recommends a method that gives higher accuracy in determining the number of gyrations at which a mixture reaches 4 percent air voids. A diverse group of mixtures, each having different properties, was examined, and an improved method for predicting the number of gyrations to accurately produce 4 percent air voids in the compacted mixture was determined.

Indirect Tensile Test (IDT) to Determine Asphalt Mixture Performance Indicators during Quality Control Testing in New Jersey

2018 ◽  
Vol 2672 (28) ◽  
pp. 394-403 ◽  
Author(s):  
Thomas Bennert ◽  
Edwin Haas ◽  
Edward Wass
Keyword(s):  
Quality Control ◽  
Tensile Test ◽  
Asphalt Mixture ◽  
Performance Testing ◽  
Fatigue Cracking ◽  
Test Methods ◽  
Mixture Design ◽  
Indirect Tensile Test ◽  
Quality Control Testing ◽  
Indirect Tensile

In recent years, there has been a growing interest in incorporating performance testing during the mixture design and quality control testing of asphalt mixtures. The move toward utilizing performance related specifications (PRS) and balanced mixture design concepts have pushed the need for asphalt mixture performance testing to the forefront. Numerous researchers have proposed a variety of laboratory tests that have showed promise at predicting asphalt mixture performance, yet most of these test methods are never adopted due to a number of issues often cited by the asphalt industry: (1) equipment cost; (2) equipment/test method complexity; and (3) time/labor effort required. The research presented here summarizes the effort to evaluate the indirect tensile test (IDT) as a potential performance indicator for hot-mix asphalt that can be easily utilized during quality control testing at an asphalt plant. Utilizing the same test equipment and basic procedure, both high-temperature rutting and intermediate-temperature fatigue cracking can be evaluated in a timely manner. Comparison testing to more standardized and accepted rutting and fatigue cracking test methods have shown excellent agreement, indicating that the suite of IDT tests have potential for adoption within a quality control testing program. Examples of criteria are given utilizing the New Jersey Department of Transportation’s (NJDOT) PRS.

scholarly journals A GPR-Based Pavement Density Profiler: Operating Principles and Applications

2021 ◽  
Vol 13 (13) ◽  
pp. 2613
Author(s):  
Nectaria Diamanti ◽  
A. Peter Annan ◽  
Steven R. Jackson ◽  
Dylan Klazinga
Keyword(s):  
Asphalt Pavement ◽  
Wave Impedance ◽  
Asphalt Mixtures ◽  
Void Content ◽  
Air Voids ◽  
New Instrument ◽  
Pavement Engineering ◽  
And Performance ◽  
Air Void ◽  
Air Void Content

Density is one of the most important parameters in the construction of asphalt mixtures and pavement engineering. When a mixture is properly designed and compacted, it will contain enough air voids to prevent plastic deformation but will have low enough air void content to prevent water ingress and moisture damage. By mapping asphalt pavement density, areas with air void content outside of the acceptable range can be identified to predict its future life and performance. We describe a new instrument, the pavement density profiler (PDP) that has evolved from many years of making measurements of asphalt pavement properties. This instrument measures the electromagnetic (EM) wave impedance to infer the asphalt pavement density (or air void content) locally and over profiles.

Implementation of modulus-based quality control testing for pavement construction in Thailand

2017 ◽  
pp. 807-811
Author(s):  
A. Sawangsuriya ◽  
P. Jitareekul ◽  
Y. Taesiri ◽  
S. Sirisak ◽  
W. Lawanwisut
Keyword(s):  
Quality Control ◽  
Quality Control Testing ◽  
Pavement Construction

scholarly journals Quality of selected anti-retroviral medicines: Tanzania Mainland market as a case study

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Sophia Mziray ◽  
Betty A. Maganda ◽  
Kissa Mwamwitwa ◽  
Adam M. Fimbo ◽  
Seth Kisenge ◽  
...  
Keyword(s):  
Quality Control ◽  
Screening Test ◽  
Product Information ◽  
Healthcare Delivery ◽  
Antiretroviral Drugs ◽  
World Health ◽  
Fixed Dose ◽  
People Living With Hiv ◽  
Quality Control Testing

Abstract Background Antiretroviral drugs (ARVs) have significantly reduced morbidity, mortality and improved the quality of life of people living with HIV infection. Poor quality ARVs may result in harmful consequences such as adverse drug reactions, treatment failure and development of drug resistant strains and sometimes death, which in turn may undermine the healthcare delivery system. To ensure optimal treatment outcomes, medicines quality control must be undertaken regularly. This study was aimed at evaluating the quality of ARVs circulating on the Tanzania Mainland market. Methods This was a survey study. ARVs samples were collected in 20 regions of Tanzania Mainland, between 2012 and 2018. All sampled ARVs were subjected to screening testing using the Global Pharma Health Fund® Mini-Lab kits. Sampled ARV’s that failed screening test or yielded doubtful results and 10 % (10 %) of all that complied with the screening test requirements were selected for full quality control testing. Quality control testing was conducted at the Tanzania Medicines and Medical Devices Authority (TMDA) laboratory a World Health Organisation prequalified. Samples collected from the medicine distribution outlets were also, subjected to product information review. Results A total of 2,630 samples were collected, of which 83.7 % (2200/2630) were from port of entry (POEs). All sampled ARVs were screened and conformed to the specifications, except of the fixed dose combination (FDC) lopinavir/ritonavir 0.27 % (7/2630) and lamivudine/zidovudine/nevirapine 0.27 % (7/2630) that failed the disintegration test. Out of the 100 samples selected for full quality control testing, 3 % of them failed to comply with the specifications, of which FDC stavudine/lamivudine/nevirapine failed disintegration and assay tests 2 % (2/100) and 1 % (1/100), respectively. Samples failing the assay test had low content of stavudine (86.6 %) versus specification limits (90 -110 %). Out of the 430 samples which were subjected to product information review, 25.6 % (110/430) failed to comply with the TMDA packaging and labelling requirements. Conclusions The quality of majority of ARVs circulating on the Tanzania Mainland market was good, even so, significant deficiencies on labelling and packaging were observed. These results call for continuous monitoring of quality of medicines circulating on the Tanzania Mainland market.

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