Study on the Suitability of Reclaimed Asphalt Pavement Aggregate (RAPA) in Hot Mix Asphalt Production

Abstract

The main objective of this study was to evaluate the suitability of recycled asphalt aggregate with fresh aggregate in hot mix asphalt production by using experimental laboratory investigation. Also, Non-probable sampling techniques were adopted to collect a sample. The engineering properties of extracted Reclaimed asphalt pavement aggregate and the fresh crushed aggregate were identified based on standard specification before starting the Marshall Mix design, Then the Marshall Stability test was conducted on crushed aggregate with three different aggregate gradation sizes 5.0%, 5.5% and 6.0% by weight of aggregates and with five different bitumen content 4.0%, 4.5%, 5.0%, 5.5% and 6.0% by weight of total mix. Depending on the selected aggregate gradation Marshall Stability test was conducted for reclaimed asphalt pavement aggregate with a replacement rate of 5.0%, 15%, 25%, 35%, 45%, 55%, and 65% by weight of crushed aggregate to determine its optimum bitumen content according to National Asphalt Pavement Association method (NAPAM). A total of 64 mix designs and 190 specimens were prepared. Hence, Marshall Stability and Moisture Susceptibility test with 3-trials, hence rutting test with 2-trials. From 190 specimens, 45 were for the control mix, 105 were for replacement proportion, 36 were for Moisture Susceptibility and 4 were for Rutting Based on the Marshall Test results and their performance tests such as Moisture Susceptibility and Rutting was performed to maximum allowable replacement percentage was compared with standard specification. The optimum bitumen content result obtained in percent was 5.1, 5.04, 4.98, 4.87, 4.81, 4.74, 4.67 and 4.53 for 0 % (control), 5.0%, 15%, 25%, 35%, 45%, 55% and 65%, respectively. The experimental value of Tensile Strength Ratio, proportional rut depth and mean rut depth on 45% RAPA replacement was 85.42% and 4.48 %, 2.24 mm respectively. Finally, the test result obtained from the marshal stability and the performance testes indicates that up to 45% replacement of aggregate is reclaimed asphalt pavement aggregate in hot mix asphalt production satisfies the standard specification.

Potential Use of Reclaimed Asphalt Pavement Aggregate and Waste Plastic Bottles for Sustainable Asphalt Pavement Production

“…Low flow values may suggest a mix has more voids and insufficient asphalt binder, which makes a crack mixture brittle. High flow values, on the other hand, show that the mix contains a high amount of asphalt binder that fills all voids and affects the resistance to permanent deformation under traffic [5]. The flow of the RAPA partially replaced content is higher than the flow of the CSA mix and the flow rises steadily over time.…”

“…Although Pakistan has emerged as one of the world's leading road-building nations, many of its roads are deteriorating or approaching the end of their useful lives [3]. In Ethiopia, traditional disposal practices involve sacrificing old asphalt layers by discarding them as garbage instead of replacing them with new asphalt [5]. WPB and RAPA are increasingly employed for pavement rehabilitation worldwide.…”

“…To achieve these benefits, transportation authorities globally began incorporating between 20% and 50% RAPA in hot mix asphalt (HMA) mixtures, with some HMA pavements even reaching up to 80% RAP [8]. Ethiopia, experiencing a 10.9% economic development between 2004 and 2015, has recently allocated 3% of its gross domestic product to road projects, with a significant portion of these investments directed toward the reconstruction, expansion, and modernization of existing highways [5]. Despite this, RAPA aggregate in the country still holds significant untapped potential and is not widely utilized in surface, base, and sub-base courses.…”

A Study on Life Cycle Analysis of Bituminous and Cement Concrete Pavements with Recycled Materials in Circular Economy

“…From the test results, they found that the highest Marshall stability value was obtained for a mix containing 30% RAP content [18]. The suitability of RAP in HMA production with varied RAP contents from 5 to 65% by weight of crushed aggregates was studied and concluded that the optimum replacement of RAP aggregates up to 45% with crushed aggregates satisfied the requirements of Ethiopian Roads Authority (ERA), Pavement Design Manual (2013) and Asphalt Institute Manual Series [19]. Marshall stability and flow values were improved as the addition of RAP content was increased and a study reported that the highest stability of 15.1kN was observed for the mix containing 75% RAP with 4% binder content [20].…”