Georgia’s Experience with Recycled Roofing Shingles in Asphaltic Concrete

1998 ◽  
Vol 1638 (1) ◽  
pp. 129-133 ◽  
Author(s):  
Donald E. Watson ◽  
Andrew Johnson ◽  
Hem R. Sharma

Reuse of roofing shingle waste not only minimizes the environmental problems related to the disposal of waste in landfills, but also reduces the amount of virgin asphalt cement and fine aggregate required in hot mix asphaltic concrete (HMAC), thus creating the potential for cost savings. The Georgia Department of Transportation (GDOT) has experimented with the recycling of roofing shingles in HMAC by constructing two test sections in 1994 and 1995. The source of the roofing shingles used in both test sections was waste generated by a roofing manufacturer; this generally consisted of discolored or damaged shingles. One test section was constructed on Chatham Parkway in Chatham County and one on State Route 21 in Effingham County. GAF Building Materials, Inc., located in Savannah, provided the waste shingle material; APAC Georgia, Inc., also located in Savannah, produced and placed these experimental mixtures. To date, both test sections are performing well compared with the unmodified control sections. Based on the performance of these test sections, shingle manufacturing waste is allowed as a recycling material in HMAC, just as reclaimed asphalt pavement is, for GDOT projects. A specification allowing postconsumer roofing shingle waste to be used is also being proposed.

Author(s):  
Shawn S. Hung ◽  
Mohammad Zia Alavi ◽  
David Jones ◽  
John T. Harvey

Rubberized hot-mix asphalt (RHMA) has been widely used in construction projects by the California Department of Transportation (Caltrans) for the environmental benefits of its recycled waste tires and for its improved fatigue and reflective cracking resistance. Currently, Caltrans does not permit the use of reclaimed asphalt pavement (RAP) in any gap- or open-graded rubberized asphalt mixes. However, given the cost and environmental benefits of RAP to replace portions of required virgin binder and aggregates in conventional mixes, interest is growing in the addition of some RAP to RHMA mixes as well. This study investigated concerns about this proposed practice. Three phases of laboratory testing (i.e., asphalt binder testing, fine aggregate matrix mix testing, and full-graded mix testing) were conducted to evaluate the effects of the addition of RAP into new RHMA mixes. The results indicated that the gap-graded aggregate structure of RHMA might limit the amount of RAP that could be used in the mix. Only 10% RAP by binder replacement could be achieved for the mix tested in this study, but the other specified volumetric requirements were still met. Replacement of a portion of asphalt rubber binder with age-hardened RAP binder increased the binder stiffness at low and high temperatures, which indicated enhanced rutting performance but diminished low-temperature cracking performance. Test results from full-graded mixes indicated similar trends, with improved rutting performance with the addition of RAP but also with significantly poorer fatigue and reflective cracking resistance.


2022 ◽  
Vol 2153 (1) ◽  
pp. 012007
Author(s):  
Y W Yung-Vargas ◽  
H A Rondón-Quintana ◽  
J E Córdoba-Maquilón

Abstract Reclaimed asphalt pavements are obtained from existing pavements through recovery techniques and are used for new asphalt mixtures production with the inclusion of virgin aggregates and asphalt cement, constituting environmentally friendly mixtures at a lower total cost, by requiring fewer quantities of new materials. This research, unlike the studies found on the subject, focuses on the study of reclaimed asphalt pavement by analyzing its granulometric distribution and asphalt cement content. For this purpose, representative reclaimed asphalt pavement samples were taken from four Colombia cities, to verify their heterogeneity. The obtained reclaimed asphalt pavement was analyzed in the laboratory, to obtain the material granulometric distribution, through extraction and asphalt content tests, following Colombian regulations from the “Instituto Nacional de Vías”. The results show that the granulometry of all cities has a central tendency (average) that moves towards an upper limit in the 2 mm particles. When analyzing the granulometry separately of the four cities, it is observed that they present a different trend in their granulometry, which shows their heterogeneity. The asphalt cement content presented values between 4.0% and 5.0%.


Author(s):  
Mohamed Elkashef ◽  
Shawn S. Hung ◽  
David Jones ◽  
John Harvey

A number of predictive models, such as the Hirsch and Al-Khateeb models, have been proposed to determine the properties of asphalt binders from asphalt concrete mix testing results. Fine aggregate matrix (FAM) mix testing can also provide useful insights into the likely performance of asphalt concrete mixes. Consequently, FAM mix testing can be an appropriate means of assessing the predictive power of these models. In this study, FAM mixes prepared with two virgin binders, PG58-28 and PG64-16, and then with different percentages of reclaimed asphalt pavement (RAP) were tested to determine their stiffness and phase angle using temperature-frequency sweeps in a dynamic shear rheometer. The data from the control mixes with no RAP were used along with the rheological properties of the virgin binders to fit the Hirsch and Al-Khateeb models. The fitted models were then used to estimate the properties of the binders in the 15% and 25% RAP FAM mixes. A comparison of the estimated binder properties with the measured binder properties clearly indicated that the fitting parameters are binder dependent. Moreover, the estimated binder moduli deviate from the measured moduli, particularly at high temperatures. The estimated complex shear moduli from the model were found to be consistently higher than the measured shear moduli values of the chemically extracted binders. It was thus concluded that the predictive models studied, in their current form, fail to provide a reliable estimate of the binder properties in mixes containing RAP.


2009 ◽  
Vol 6 (1) ◽  
pp. 37 ◽  
Author(s):  
Salim Al-Oraimi ◽  
Hossam F. Hassan ◽  
Abdulwahid Hago

Reclaimed Asphalt Pavement (RAP) is the result of removing old asphalt pavement material. RAP consists of high quality well-graded aggregate coated with asphalt cement. The removal of asphalt concrete is done for reconstruction purposes, resurfacing, or to obtain access to buried utilities. The disposal of RAP represents a large loss of valuable source of high quality aggregate. This research investigates the properties of concrete utilizing recycled reclaimed asphalt pavement (RAP). Two control mixes with normal aggregate were designed with water cement ratios of 0.45 and 0.5. The control mixes resulted in compressive strengths of 50 and 33 MPa after 28 days of curing. The coarse fraction of RAP was used to replace the coarse aggregate with 25, 50, 75, and 100% for both mixtures. In addition to the control mix (0%), the mixes containing RAP were evaluated for slump, compressive strength, flexural strength, and modulus of elasticity. Durability was evaluated using surface absorption test. 


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