PERFORMANCE EVALUATION OF DENSE GRADED COLD MIX ASPHALT

Transcription

1 International Journal of Civil Engineering and Technology (IJCIET) Volume 9, Issue 10, October 2018, pp , Article ID: IJCIET_09_10_056 Available online at ISSN Print: and ISSN Online: IAEME Publication Scopus Indexed PERFORMANCE EVALUATION OF DENSE GRADED COLD MIX ASPHALT A. K. Arshad, E. Shaffie, F. Ismail Institute for Infrastructure Engineering and Sustainable Management (IIESM), Universiti Teknologi MARA, Shah Alam, Selangor, Malaysia W. Hashim, Z. Abd Rahman Faculty of Civil Engineering, Universiti Teknologi MARA, Shah Alam, Selangor, Malaysia ABSTRACT Cold Mix Asphalt (CMA) offer many environmental and economic advantages compared to Hot Mix Asphalt (HMA), particularly on its low requirement for energy. However, CMA is generally thought to be less superior in performance, compared to HMA. The objective of this study is to determine the volumetric properties of CMA and to evaluate the moisture resistance, resilient modulus and rutting performance. CMA mixes with and without cement as additive were prepared using Marshall mix design method. Marshall Properties were analysed to confirm compliance with the PWD Malaysia s specification requirements. The moisture susceptibility for the mixes was then evaluated, resilient modulus test was performed to measure the stiffness of the mixes while the Hamburg wheel tracking test was used to evaluate the rutting performance of these mixes. It was found that the tensile strength ratio for the CMA mixes was higher than 80% and therefore provide sufficient moisture resistance. The addition of cement in the CMA mixes resulted in the increase in resilient modulus value.the rutting performance in specimens with cement was also found to perform better than specimens without cement. The results also showed that the addition of 2% Portland cement accelerated their curing time and significantly improved the performance of the mixes. It can be concluded that CMA is a viable alternative to hot mix asphalt for use as pavement surfacing material. Key words: Cold mix asphalt, Cold Bituminous Emulsion Mixes, Dense Graded Mixes, Moisture Susceptibility, Resilient modulus, Rutting. Cite this Article: A. K. Arshad, E. Shaffie, F. Ismail, W. Hashim, Z. Abd Rahman, Performance Evaluation of Dense Graded Cold Mix Asphalt, International Journal of Civil Engineering and Technology (IJCIET) 9(10), 2018, pp editor@iaeme.com

2 A. K. Arshad, E. Shaffie, F. Ismail, W. Hashim, Z. Abd Rahman 1. INTRODUCTION Hot mix asphalt is the conventional material used for road construction and has satisfied the requirements for asphalt surfacing over many years. In hot mix asphalt construction, the production process is conducted at high temperature in the range of about 135 o C to 163 o C (275 o F to 325 o F) [1-3]. There are several drawbacks in the use of hot mix asphalt such as environmental degradation, high energy consumption, increase in carbon footprint, low output for mix production, limited construction period in a year due to bad weather, oxidative hardening of binder, health and safety hazard to workers [4-5]. Cold mix asphalt (CMA), also known as cold bituminous emulsion mix, can serve as an alternative to HMA for a wide range of paving applications, particularly for preventive maintenance and repair [5-6]. Compared to HMA and Warm Mix Asphalt (WMA) [7-8], CMA has a number of benefits that makes it a promising alternative to both types of asphalt mixes [9]. Some of the benefits of CMA include the reduction in heating energy during its production and longer working time for transportation and placing the mix. CMA can provide an energy saving of up to 50% compared with hot mix asphalt. CMA construction is carried out at the ambient temperature between 23 o C to 25 o C [10]. Uemura and Nakamori conducted both laboratory and field studies on cold mixes and concluded that cold mixes were more environmental friendly due to the elimination of dust and gaseous emissions as the aggregate and emulsified asphalt did not have to be dried for use in asphalt mixtures [11]. They also found that the performance of cold mixes is acceptable as a road surfacing material. In addition to this, field trials proved that cold mix can be easily produced by using a conventional hot mix plant and laid using similar techniques as HMA. It is also a labour friendly technology. Other than that, cold mix can also be laid during wet or humid condition and economical and high production is possible with low investment. Despite the benefits of CMA, there are some problems faced using cold mix, for example, high air-void content in the compacted mixes and long time required to achieve fully cured samples for maximum performance [12]. To modify the cold mix properties, additives such as cement, lime, fly ash were used to increase the performance of cold mix. Most of the researchers suggested using cement as additive as it improved the mix properties and result in highly satisfactory performance [13]. Researchers recommended different laboratory procedures of curing time and others parameters in order to evaluate the suitable mechanical properties. Until now, unlike HMA, where the Marshall and Superpave design methods are widely used, there is no accepted cold mix design method available hence research on cold mix is still going nowadays. Also, hot mix technology has made significant advances through many research programs but cold mix asphalt technology is lagging behind in both research and application fields especially in a developing country like Malaysia. The purpose of this study is to determine the suitability of using the Marshall mix design method for the determination of optimum emulsion content and to evaluate the performance of CMA in terms of moisture susceptibility, resilient modulus and rutting. Cement is used as additive to increase the performance of CMA so that a more durable asphalt mix can be achieved [14]. 2. MATERIALS AND METHODS 2.1. Materials The aggregate used were sourced from Kajang Rock Quarry, Selangor. The aggregate tests conducted for this study are Los Angeles Abrasion Value, Aggregate Impact Value, editor@iaeme.com

3 Performance Evaluation of Dense Graded Cold Mix Asphalt Aggregate Crushing Value and Flakiness Index Value. The AC14 aggregate gradation as shown in Table 1was used in accordance to JKR/SPJ/2008-S4 [15]. Table 1 Aggregate Gradation (PWD Malaysia, 2008) Mid Designation AC 14 B.S Sieve % Passing By Weight 28.0 mm mm mm mm mm mm mm µm µm µm 4 8 The bitumen emulsion was sourced from ACP-DMT, Port Klang and the residual asphalt content of the emulsion was 61.8%. The range of emulsion content used in this study was 5.7%, 6.5%, 7.3%, 8.1% and 8.9%. This range of emulsion content was suggested by Chatterjee et al. (2005) in their study [16]. This range of emulsion content is equivalent to 3.5%, 4.0%, 4.5%, 5.0% and 5.5% residual asphalt content. The calculation of emulsion content is determined as follows: % Residual Asphalt (P) = Emulsion Content (EC) x % binder in emulsion For example, to obtain the required emulsion content (EC) for 3.5% residual bitumen content, the calculation is as follows: 3.5 % = EC (%) x EC (%) = 5.7 % 2.2. Sample Preparation and Testing Procedure The laboratory specimens were prepared to determine the optimum emulsion content (OEC) and to test the performance of CMA for moisture susceptibility, resilient modulus and rutting. For the determination of Optimum Emulsion Content (OEC), samples were prepared at 5.7%, 6.5%, 7.3%, 8.1% and 8.9% emulsion contents. The samples were prepared in accordance to ASTM D1559 [17] to determine OEC using the Marshall Test method. Resilient modulus test was performed on the Marshall samples in accordance to ASTM D 4123 [17]. Testing temperatures of 35 C was used and loading of 1200N with load pulse of 0.1 seconds and rest period of 0.9 seconds were set. Samples for the moisture susceptibility test were prepared at the optimum emulsion content (OEC). Modified Lottman test was performed in accordance to the AASHTO T-283 procedure [18] to evaluate the moisture susceptibility of the samples. For rutting performance test, prior to the mixing process, the aggregate is heated in the oven at temperature of 110 ± 5 0 C for 24 hours and the emulsion is heated for minutes at a temperature of 72 o C. The samples were then mixed with the bitumen emulsion at OEC and for minutes or until all the aggregates were evenly coated. Then, the samples were cured in the oven at a temperature of 60 ± 5 0 C for 96 hours. At every 24 hours, the samples were weighed to determine the curing time. After 96 hours, the samples were compacted in a 150 mm diameter mould using a Gyratory Compactor by applying 80 gyrations. The Asphalt Pavement Analyzer (APA) machine was used for rutting performance test in accordance to AASHTO T340 [18] editor@iaeme.com

4 Flow (mm) VFB Marshall Stability (kn) VIM A. K. Arshad, E. Shaffie, F. Ismail, W. Hashim, Z. Abd Rahman 3. RESULT AND DISCUSSION This section presents the results, analysis and discussion of the laboratory testing carried out on the CMA mixes. First, the determination of optimum emulsion content and curing time are presented. Then, the results of performance tests carried out in terms of moisture susceptibility, resilient modulus and rutting performance are presented and discussed Optimum Emulsion Content Marshall mix design was carried out to determine the volumetric properties of the mixture. The volumetric properties determined included bulk specific gravity, air void, voids in mix (VMA), stability and flow. The Optimum Emulsion Content (OEC) for the sample with and without cement were determined from the individual plots of bulk specific gravity (SG), air voids in mix (VIM), voids filled with bitumen (VFB), flow and stability versus percent emulsion content as shown in Figures 1 to VIM vs Emulsion Content 0% Cement 2% Cement Figure 1 Bulk SG versus Emulsion Content Figure 2 VIM versus Emulsion Content VFB vs Emulsion Content % Cement % Cement Figure 3 VFB vs Emulsion Content Marshall Stability vs Emulsion Content % Cement 2% Cement Figure 4 Marshall Stability vs Emulsion Content Flow vs Emulsion Content % Cement % Cement Figure 5 Flow versus Emulsion Content editor@iaeme.com

5 Weight of Sample (g) Performance Evaluation of Dense Graded Cold Mix Asphalt The OEC was determined from the arithmetic mean of the results from the five curves plotted and the value was cross-checked with the limits set in Public Works Department specification. Table 3 shows the Optimum Emulsion Content (OEC) for both samples. The OEC obtained for samples without cement is 6.8% and OEC for sample with cement is 6.5%. Table 3 Determination of OEC based on Marshall Mix Design Properties Sample with Sample with 2% 0% cement cement Max. Bulk S.G % Max. Stability mm OEC (%) Curing Time Figure 6 shows the result of curing time represented using weight of sample versus time in hour. The curing time was analysed for optimum emulsion content for both samples with and without cement. The weight of sample without cement showed a decrease of about 40 g after 24 hours and remains constant after that. Similarly, the weight for sample with cement shows a reduction of 20 g after 24 hours and the weight remain constant after that. The weight of sample with cement reduced less than the sample without cement. This is likely due to the amount of water reacting during the hydration of cement in the sample WEIGHT OF SAMPLE vstime 0 hr 24 hr 48 hr 72 hr 96 hr Time (hr) 0% cement 2% cement Figure 6 Curing Time for Samples 3.3. Moisture Susceptibility The Indirect Tensile Strength test (ITS) was conducted for both unsoaked and soaked specimen at the optimum emulsion content (OEC). Figure 7 shows the results of ITS for unsoaked and soaked samples for both control mix and cement modified mix. The addition of cement in the mix gave the higher ITS values at MPa for unsoaked specimen and for soaked specimen, the ITS value is MPa. Control mix has the lower value of ITS which is MPa for unsoaked specimen and MPa for soaked specimen. The ITS value shows that cement can increase the strength for the mix editor@iaeme.com

6 A. K. Arshad, E. Shaffie, F. Ismail, W. Hashim, Z. Abd Rahman Figure 7 Indirect Tensile Strength for Unsoaked and Soaked Specimen The Tensile Strength Ratio (TSR) values for mix without cement and mix with cement are shown in Figure 8. From the results, it shows the TSR values for cement modified mix is higher compared to mix without cement where the TSR values is 89.8% and 88.1% respectively. The cement modified mix indicates that it is less susceptible to moisture damage compared to control mixes. The cement modified mix can develop strength and were more resistant to water damage. However, all cold mix specimens have adequate resistance to moisture damage and complied with the required minimum value which is 80% according to AASHTO T-198. Therefore, the addition of cement improved the moisture resistance of CMA. Figure 8 Indirect Tensile Strength Retained (TSR) 3.4. Resilient Modulus The results of resilient modulus test for samples without cement and samples with cement at a temperature of 35 C is shown in Figure 9. The highest resilient modulus value of sample without cement is 2556 MPa at 7.3% emulsion content. The highest resilient modulus value of sample with cement is MPa at 6.5% emulsion content. The result shows that resilient modulus increased when the emulsion content increased until it reached peak value and start declining at 7.3% emulsion content for sample with cement and at 8.1% emulsion content for editor@iaeme.com

7 Resilient Moduus (MPa) Performance Evaluation of Dense Graded Cold Mix Asphalt sample without cement. It is likely that the cement reacted with existing water in the bitumen emulsion, which caused the hydration and binding action with aggregate. Resilient Modulus vs Emulsion Content o% cement 2% cement Figure 9 Resilient Modulus of Samples 3.5. Rutting Performance The results for rutting evaluation is shown in Table 4. Rutting depth was measured at 25, 4000 and 8000 repetitions (stroke count) of loaded wheel on the samples. For 25 repetitions, the sample without cement has a higher rut depth of 0.18 mm compared to sample with cement at 0.15 mm. At 4000 repetitions, the rut depth increased further for both; the rut depth for sample without cement was 2.89 mm while sample with cement was 2.82 mm. At 8000 repetitions, the sample without cement has higher rutting depth of 4.38 mm compared to the sample with cement that has a 4.30 mm rut depth. Therefore, it can be inferred that sample with cement has better rut resistance compared to sample without cement. In addition, a small amount of cement can effectively work to accelerate the moisture loss and hence the mixture strength gains faster at early age and reducing the measured rutting. Table 4. Results for rutting evaluation Repetitions (Strokes) Sample with 0% cement Rut Depth (mm) Sample with 2% cement CONCLUSIONS The performance of CMA was evaluated by conducting the moisture susceptibility, resilient modulus and rutting tests. The moisture susceptibility results showed that the TSR value for cement modified mixtures is higher compared to control mixes and these values complied with the 80% minimum requirement. In addition, the resilient modulus results shows that cement modified mixtures exhibits higher resilient modulus compared to control mix. This is likely due to the cement which caused the mix to be stiffer. The sample with cement also has editor@iaeme.com

8 A. K. Arshad, E. Shaffie, F. Ismail, W. Hashim, Z. Abd Rahman lower rutting depth compared to the sample without cement. Based on the results, it can be concluded that the performance of CMA when properly designed and fully cured (even without cement) are comparable to hot mix asphalt. ACKNOWLEDGEMENTS Special thanks to the Research Management Institute (RMI) of Universiti Teknologi MARA for providing the financial support under the Geran Insentif Penyeliaan (GIP) fund. The authors would like to thank the Faculty of Civil Engineering, Universiti Teknologi MARA, Shah Alam, Malaysia for providing the experimental facilities and to all technicians at Highway and Traffic Engineering Laboratory. REFERENCES [1] Brown, E.R., Kandhal, P.S., Roberts, F.L., Kim, Y.R., Lee, D. & Kennedy, T.W., Hot Mix Asphalt Materials, Mixture Design and Construction. 3 rd ed. Lanham: NAPA Research and Education Foundation, [2] Arshad, A.K., Shaffie, E., Ismail, F., Hashim, W., Abd Rahman, Z. Asphaltic concrete evaluation for mechanistic pavement design. International Journal of Civil Engineering and Technology, 9(8), 2018, pp [3] Kamil Arshad, A., Awang, H., Shaffie, E., Hashim, W., Abd Rahman, Z. Performance Evaluation of Hot Mix Asphalt with Different Proportions of RAP Content. E3S Web of Conferences, 34 (01026), [4] D. Leech. Cold Bituminous Materials for Use in the Structural Layers of Roads. Transport Research Laboratory, Wokingham, [5] Indian Road Congress. Use of Cold Mix Technology in Construction and Maintenance of Roads using Bitumen Emulsion, New Delhi: Indian Road Congress, [6] Maccarone, S., Holleran G., and Ky, A. Cold Asphalt Systems as an Alternative to Hot Mix., Asphalt Review, 14 (1), 1995, pp [7] Kridan, F.A.M., Arshad, A.K., Rahman, M.Y.A., Development of warm mix asphalt and compliance with the requirements set by specifications. European Journal of Scientific Research, 48(1), 2010, pp [8] Arshad, A.K., Kridan, F.A.M., Kamaluddin, N.A., Shafie, E., Evaluation of warm mix asphalt performance with high RAP content. Jurnal Teknologi, 73(4), 2015, pp [9] Ling, C., Developing Evaluation Method of Moisture Susceptibility for Cold Mix Asphalt. Unpublished master's thesis, University Wisconsin-Madison, [10] Durga, M., Effect of Mix Parameters on Performances and Design of Cold Mix Asphalt. International Journal of Research Sciences and Advanced Engineering, 2(11), 2015, pp [11] Uemura, T. and Nakamori, Y. Stabilization Process of Cement Asphalt Emulsion in Japan. Proceedings of First World Congress on Emulsions, Paris, 1993, pp [12] Thanaya, I. N. A. Evaluating and Improving The Performances of Cold Asphalt Emulsion Mixtures. Civil Engineering Dimension, 9(2), 2007, pp editor@iaeme.com

9 Performance Evaluation of Dense Graded Cold Mix Asphalt [13] Dash, S.S.. Effect of Mix Parameters on Performances and Design of Cold Mix Asphalt. Unpublished master's thesis, National Institute of Technology, Rourkela, India, [14] Ling, C., Hanz, A. & Bahia, H. Evaluating Moisture Susceptibilty of Cold-Mix Asphalt. Journal of the Transportation Research Board, Washington D.C.:TRB, 2446, 2014, pp [15] Public Works Department Malaysia. Standard Specification for Road Works, Section 4: Flexible Pavement. (JKR/SPJ/2008-S4). Kuala Lumpur: PWD Malaysia, [16] Chatterjee, S., Ronald, P.W., Smit, A., Prozzi, J., and Prozzi, J.A., Development of Mix Design and Testing Procedures for Cold Patching Mixtures. Center for Transportation Research, University of Texas at Austin, [17] ASTM. Annual Book of ASTM Standards (Vol Road and Paving Materials; Vehicle-Pavement Systems). West Conshohocken, PA: American Society for Testing and Materials, [18] AASHTO, Standard Specifications for Transportation Materials and Methods of Sampling and Testing, Washington D.C.: American Association of State Highway and Transportation Officials,