Transactions Template JOURNAL OF ENGINEERING RESEARCH AND TECHNOLOGY, VOLUME 5, ISSUE 1, MARCH 2018 1 Porous Asphalt: A New Pavement Technology in Palestine Shafik Jendia 1 , Ziad AlDahdooh 2 Mohammed AbuRahma 2 , Mahmoud AbuJayyab 2 , AbdElkarim ElDahdouh 2 . 1, Professor of Highway Engineering, Islamic University of Gaza, Palestine 2, Faculty of Engineering, Islamic University of Gaza, Palestine Abstract—Porous Asphalt (PA) is researched and produced in Europe and the United States of America to in- crease the skid resistance of the asphalt surface. This can be caused when storm water infiltrate directly in the ground through the porous surface layer. So far, in Palestine this type of pavement has not been used. If PA is used in Palestine, it may contribute to solving many of the local problems especially groundwater deficit. There- fore, this research deals with studying the possibility of producing Porous Asphalt as new pavement technology in Palestine. Based on several international researches, a proposal for the limits of aggregate gradation was deter- mined. To investigate the applicability of using local material and the proposed gradation limits, several tests were conducted, including sieve analysis, specific gravity, absorption, abrasion, impact and crushing value. Bitumen tests were also conducted such as, penetration test, softening point, ductility and specific gravity. Also, asphalt mixtures were prepared in accordance with the proposed gradation curves, followed by testing of 24 PA- speci- mens to determine the mechanical properties, especially stability, flow, and bulk density. The results showed that any aggregate blending curve lie between the limits of proposed gradation can be used to produce PA. Marshall test results showed that the optimal bitumen content was approximately 4% by the weight of total mixture, and the void ratio obtained was approximately 21% for the produced asphalt. Index Terms— Porous Asphalt, Marshall, void ratio, aggregate gradation. I. INTRODUCTION Porous Asphalt (PA) is a new pavement technology. It has been researched and produced in several sites worldwide, especially in Europe and the United States. The surface permeability and high porosity of PA allow water to pass vertically through the pavement to the subgrade below to naturally recharging groundwater levels. The water in the base is stored temporarily in stone reservoir consisting of uniformly graded layer thick enough to allow sufficient water storage during anticipated rain events, clean crushed stone with around 40% voids, often allowed to infiltrate into permeable subgrade soils, and can recharge the groundwater direct- ly [1, 2, 3, 4]. Unlike conventional pavements, PA is typically built over an uncompacted subgrade to maximize infiltration water into the soil. Above the uncompacted subgrade is a geotextile fabric, which prevents the migration of fines from the subgrade into the stone recharge bed while still allowing for water to pass through, as shown in Figure (1). PA has not been used in Palestine despite its poten- tial benefits like reducing runoff, which leads to increas- ing the skid resistance and improving surface water quality which infiltrate directly in the ground through the porous surface layer. PA can in Palestine due to its advantages (mentioned below) contribute to solving many of local problems. The objectives of this study are: a) to determine a suitable aggregate gradation for local aggregates used in the asphalt mix. b) to determine the highest void ratio that can be reached using the local material. Figure 1: Typical section of Porous Asphalt pavement. Shafik Jendia, Ziad AlDahdooh, Mohammed AbuRahma , Mahmoud AbuJayyab, AbdElkarim ElDahdouh. Porous Asphalt: A New Pavement Technology in Palestine 2 II. ADVANTAGES There are several advantages for the Porous Asphalt pavement [1 – 8]. Some of them are summarized be- low: 1. Removing the pollutants and improving water quality. 2. Melting snow and ice fast and reducing the need for deicing salt. 3. Recharging groundwater to underlying aquifers and providing flood control. 4. Increasing permeability, potentially improving the water quality through filtering capabilities. 5. Improving water and oxygen transfer to nearby plant roots. 6. Improving skid resistance, splash, and spray, and driving speed. 7. Reducing hydroplanes on pavement surfaces by reducing glare on the road surfaces specifically dur- ing wet night conditions. 8. Absorption of noise from tires and engines (sound is not reflected but absorbed by the porous layer). 9. Reducing fuel consumption due to enhanced smoothness. 10. Reducing tires wear on the asphalt. 11. Extending pavement life due to well drained base. III. MATERIALS AND TEST RESULTS A. Materials properties In this study, all important laboratory tests were conducted to evaluate the properties of the used bitu- men. Table (1) illustrates the test results. Table 1: Bitumen properties and specifications. Bitumen Tests Test Standard Specification Test Result Specification Values Density (g/cm 3 ) AASHTO T 228-94 ASTM D 07 – 03 1.03 1.01-1.06 Penetration 1/10 mm AASHTO T 49-96 ASTM D 5 – 97 68.33 60-70 Ductility (cm) AASHTO T 51-94 ASTM D 113 – 99 150 Min 100 Softening Point (℃) AASHTO T 53-96 ASTM D 36 – 95 49.6 Min 48 Max 56 Flash and Fire points AASHTO T 48-96 ASTM D 92 – 02 b 286 +326 Min 230 Max 330 Also, laboratory tests were conducted on the aggregate to determine their properties. Table (2) illustrates the tests results. Table 2: Aggregates test results according to ASTM specifications. Aggregates Tests Specification Test result Specific Gravity (g/cm 3 ) 2.58-2.61 Water Absorption (%) 1.87-3.0 Resistance to Degradation of Small-Size Coarse Aggregate by Abrasion in the Los Angeles Ma- chine (%) 19.2 Sieve Analysis of Fine and Coarse Aggregates See Appendix [B] Materials Finer than (No. 200) Sieve in Mineral Aggregates by Washing See Appendix [B] B. Blending of aggregates Several specifications and researches [1-10] were studied to determine the best aggregate gradation as shown in Appendix [A]. The result is presented in Fig- ure (A-1) which illustrates the gradation limits in com- parison with the international gradations. The suggested limits and the result of the aggregates blending process followed for this purpose is illustrated in in Figure (2) and in Table (3). The blending procedure [9] of all ag- gregate types are presented in Table (B-1). For this purpose, all aggregates were brought from the stock- piles available in the asphalt factories in the Gaza Strip. From Table (B-1) is clear that the part of filler (parti- cles size less than 0.075 mm) is approximately 4%. The maximum percentage (5.0 %) of filler is relatively to Figure 2: Gradation Curves in Comparison with Limits Curves that for dense asphalt is small. This means that in order to produce a large void ratio in the PA the amount of mortar (bitumen + filler) should be relative small. Table 3: Blending of stockpile aggregates. Aggregate Size (mm) Blending (%) Simsimia (0/12.5) 50 Adasia (0/25) 45 Folia (0/37.5) 5 0 20 40 60 80 100 0.01 0.1 1 10 100 P a s s i n g ( % ) Seive size (mm) Req. Blending suggested gradation limits Figure 2: Aggregate gradation curve in comparison with suggested limit curves Shafik Jendia, Ziad AlDahdooh, Mohammed AbuRahma , Mahmoud AbuJayyab, AbdElkarim ElDahdouh. Porous Asphalt: A New Pavement Technology in Palestine 3 C. Mechanical test results In order to study the mechanical properties (stability, flow, bulk density 𝝆 , air voids 𝑽 , volumetric part of bitumen content 𝑽 , voids in mineral aggregates VMA and Voids filled with bitumen VFB) of the mixture of Porous Asphalt (PA), Marshall method was used in this research. Accordingly, the selected aggregates with the determined gradation were mixed carefully with three different percentages of bitumen content in the laboratory. Eight Marshal specimens were produced for each bitumen content (24 specimens). The results of mechanical properties are given in Table (4). Table 4: Marshall test results. 𝒎 (%) Stability (KN) Flow (mm) 𝝆 (g/cm 3 ) 𝑽 (%) 𝑽 (%) VMA (%) VFB (%) 3.50 6.57 2.85 1.90 20.90 6.45 27.37 23.64 4.00 4.97 2.88 1.91 20.19 8.59 27.60 26.85 4.50 5.38 2.90 1.91 19.42 8.34 27.78 30.09 From Table (4), it is obvious that the reached air void ratio in the produced PA- specimens is relatively large (approximately 20%) comparatively to that in dense asphalt (maximum 8%). This ratio lies in the acceptable range discussed in references, mentioned above [1- 10]. D. Optimum bitumen content 𝒎 % Based on the specimen testing, the main relationships between bitumen content and the obtained values of Marshall stability, flow, bulk density and air void con- tent were presented in Table (4). The optimum bitu- men content of the mixture is the numerical average of the three values as it is described in the following equa- tion [9]: 𝒎 = ( + + 𝒄) / 𝟑 where mb = optimum bitumen content (%). a = bitumen content at maximum bulk density (%). b = bitumen content at maximum stability (%). c = bitumen content at minimum air void content (%). Table (5) illustrates the bitumen content for each prop- erty. Table 5: Mechanical properties of PA and bitumen contents Property Value 𝒎 % Maximum stability 6.75 KN 3.50 % Maximum bulk density 1.91 g/cm 3 4.50 % 𝑉 Required 20.9 % 3.50 % 𝑶𝒑𝒕𝒊𝒎𝒖𝒎 𝒎 % = 3.5 + 4.5 + 3.5 3 = 𝟑.𝟖𝟑 ≈ 𝟒% Figure (3) presents the water permeability through one of the produced specimen with va= 20.9 %. IV. CONCLUSIONS AND RECOMMENDATIONS 1. Porous Asphalt (PA) can be produced successfully with local material in Palestine, provided the gra- dation of the selected aggregate should lie within the limits suggested in Table (6). Table 6: Sieve Size Passing Percent for the limit Curves. Sieve Size (mm) Percent Passing (%) Min Max 22.4 100 100 16 93 100 12.5 85 100 11.2 70 100 9.5 5 100 4.75 5 35 2 5 15 0.075 2 5 2. The effective bitumen content obtained using Mar- shall method should be approximately 4%. Bitu- men content much less than 4% increases the pos- sibility of causing surface raveling. 3. The maximum air void ratio can be reached using local material approximately 21%. 4. Marshall stability and bulk density of PA- specimen are lower than that for the dense asphalt concrete. 5. The values of Marshall flow are suitable, they lie in the acceptable range (2- 4) mm. Figure 3: Porous Asphalt specimen while permeability test Shafik Jendia, Ziad AlDahdooh, Mohammed AbuRahma , Mahmoud AbuJayyab, AbdElkarim ElDahdouh. Porous Asphalt: A New Pavement Technology in Palestine 4 V. REFERENCES [1] Environmental Protection Agency (EPA), "Po- rous Pavement. National Pollutant Discharge Elimination System" 2007. [Online]. Available: http://cfpub.epa.gov/npdes/stormwater/menuof bmps/index.cfm. [Accessed on 1 November 2016]. [2] Lebens, M. “Porous Asphalt Pavement Perfor- mance in Cold Regions”, Minnesota Department of Transportation, Minnesota 2012. [3] Wisconsin Asphalt Pavement Association, (WAPA) "Tech Bulletin Porous Asphalt Pave- ments" Wisconsin, 2015. [4] U.S. Federal Highway Administration, (FHWA) "Porous Asphalt Pavements with Stone Reser- voirs" 2015. [5] Lori, K. S. “Porous Asphalt Pavement Designs: Proactive Design for Cold Climate”, University of Waterloo, Canada, 2007. [6] The UNH storm water center, "Porous Asphalt Pavement for Storm Water Management" 2009. [7] Cahill H., Michele, A., Courtney. M. "Storm- water Management with Porous Pavements" 2005. [8] Quantao, L. “Induction Healing of Porous As- phalt Concrete”, University of Technology, P.R. China, 2012. [9] Jendia, S. “Highway Engineering Structural de- sign”, Dar al Manara, Gaza, 2000. [10] Velske, S., Mentlein, H., Eymann, P. Strassenbau, “Strassenbautechnick”, Germany, 2778. Shafik Jendia, Ziad AlDahdooh, Mohammed AbuRahma , Mahmoud AbuJayyab, AbdElkarim ElDahdouh. Porous Asphalt: A New Pavement Technology in Palestine 5 Figure A-1: The proposed gradation limits in comparison with the international gradations APPENDIX A 0 10 20 30 40 50 60 70 80 90 100 0.01 0.1 1 10 100 P a s s i n g ( % ) Sieve Size(mm) Dutch NAPA Franklin Velske PA11 Velske PA8 suggested graduation limits Shafik Jendia, Ziad AlDahdooh, Mohammed AbuRahma , Mahmoud AbuJayyab, AbdElkarim ElDahdouh. Porous Asphalt: A New Pavement Technology in Palestine 6 APPENDIX B Aggregate Mix Aggregate Size(mm) Blending % 0-0.075 0.075-0.3 0.3-0.6 0.6-2 2-4.75 4.75-9.5 9.5-12.5 12.5-25 25-37.5 Simsimia (12.5) 5.58 1.82 0.88 4.31 31.53 55.45 0.42 50 2.79 0.91 0.44 2.15 15.76 27.73 0.21 0.00 0.00 Adasia (25) 2.72 1.31 0.21 0.31 1.22 21.18 42.31 30.73 45 1.22 0.59 0.10 0.14 0.55 9.53 19.04 13.83 0.00 Folia (37.5) 1.50 0.50 0.10 0.21 1.01 7.84 16.60 69.71 2.54 5 0.07 0.02 0.01 0.01 0.05 0.39 0.83 3.49 0.13 Total 4.09 1.52 0.54 2.31 16.36 37.65 20.08 17.32 0.13 100 Req. Blending 4.09 5.61 6.16 8.46 24.83 62.48 82.56 99.87 100 100 Min. of the proposed aggregate Gradation 2 2.3 2.8 5 5 5 85 100 100 Max. of the proposed aggregate Gradation 5 6 8 15 35 100 100 100 100 Table B-1: Local aggregate blending procedure.