EFFECT OF GRADATION AND WASTE PLASTIC ON PERFORMANCE OF STONE MATRIX ASPHALT (SMA)

Transcription

1 International Journal of Civil Engineering and Technology (IJCIET) Volume 9, Issue 9, September 2018, pp , Article ID: IJCIET_09_09_158 Available online at ISSN Print: and ISSN Online: IAEME Publication Scopus Indexed EFFECT OF GRADATION AND WASTE PLASTIC ON PERFORMANCE OF STONE MATRIX ASPHALT (SMA) Mithanthaya I.R and Shriram Marathe Department of Civil Engineering, NMAM Institute of Technology, Nitte, Karkala, Karnataka, India Ravi Shankar A.U Department of Civil Engineering, NITK, Surathkal, Karnataka, India ABSTRACT Stone Matrix Asphalt (SMA) is a gap-graded blend which possesses a high deliberation coarse aggregate framework with stone-to-stone contact along with a high binder content which adds flexibility and durability of the mix. The SMA is associate with the drain down of binder during mixing, transporting and laying of the mix. In sequence to prevent this and to improve the mix characteristics, it was proposed to study the properties of SMA by modifying it by adding waste plastics. Hence, stability, flow value, percentage drain down, and rutting characteristics of SMA mixes having different proportions of waste plastic were studied. Initially, it was decided on the basis of highest value of bulk density i.e., Chinese and Indian gradation of aggregates were selected. The Marshall Tests were conducted to find out Optimum Bitumen Content (OBC) with different proportions of bitumen and plastic content. Further, the drain down tests and rutting test using Immersion Wheel Tracking Device were also conducted on the SMA specimens at Optimum Plastic Content (OPC). From Marshall Test, for the SMA of Chinese gradation, OPC was found to be 8.0%, and that for Indian gradation it was 6.0% plastic content, respectively. Addition of waste plastic to the SMA leads to a decrease in the drain down value and satisfies the condition for both the gradations. Also, the rutting intensity was observed to be 42 per-cent greater for Indian gradation, when contrasted to that of Chinese gradation. Overall, Chinese gradation has shown the better results than the Indian gradation. Keywords: Marshall Test, Stone Matrix Asphalt (SMA), Indian Gradation, Chinese Gradation, Waste Plastic, Rutting Test editor@iaeme.com

2 Effect of Gradation and Waste Plastic on Performance of Stone Matrix Asphalt (SMA) Cite this Article: Mithanthaya I.R, Shriram Marathe and Ravi Shankar A.U, Effect of Gradation and Waste Plastic on Performance of Stone Matrix Asphalt (SMA), International Journal of Civil Engineering and Technology, 9(9), 2018, pp INTRODUCTION 1.1. GENERAL The Stone matrix asphalt (SMA) is a gap-graded blend developed at Germany, which possesses two major components in it, a high deliberation of coarse-aggregate frame and a higher bituminous binder content. The frame of coarse-aggregates provides the blend among stone-to-stone contact, providing strength, while the higher binder content adds flexibility and durability. The bituminous mortar is typically consists of fine aggregate, mineral filler, bituminous binder and a stabilizer. The stabilizer (also called the stabilizing additive) holds the bituminous binder in the mixture during production at high temperatures with placement. As the strength of SMA depends greatly on the stone-to-stone aggregate skeleton, it is vital that the blend should be adequately designed and placed through a well-built aggregate framework (IRC SP ). Superior quality and optimum amount of binder and gap-graded coarse aggregates are major requisites meant for an extended service life of SMA. In general, SMA has a high wear resistance and a good stability to enduring deformation through an admirable element interlocking and a high amount of crushed quality aggregates. It also has longevity to ravelling and premature cracking by high binder content and a void-less mastic mortar. This mortar fills the voids and binds the aggregate frame. The stabilizing additive used in SMA provided stability to the mix, in addition it assures the homogeneity (no binder drainage) of the mix during the development, haulage and laying. The studies carried-out by the Central Road Research Institute (CRRI), New Delhi on the utilization of bags of waste plastics in asphalt mixes have shown the enhancement of the properties of mix with a answer to waste-disposal problems. The outcome also indicated that, when compared to the conventional mix, there is an enhancement in mechanical properties (Kamaraj et al, 2004). Consequently, the life of roadway surfacing, utilizing the plastic waste is predictable to increase substantially in assessment with the use of conventional asphalt mix. The performance tests have also shown an doubling-up of fatigue life, increased resistance to rutting and a reduction in water damages when plastic waste was used in bituminous concrete (Allen, G. K., 2006). According to WSDOT (2000) SMA is a durable, harsh, stable, and rut-opposing mixture which relies on stone-to-stone contact with the rich mortar binder to provide strength and longevity editor@iaeme.com

3 Mithanthaya I.R, Shriram Marathe and Ravi Shankar A.U Figure 1 SMA surface 1.2. WASTE PLASTIC With the industrial upheaval, mass making of freight started, and plastic seemed to be a lowcost, inevitable and efficient raw material. It plays an integral part in the economies which have been nearly revolutionized by various applications of plastics. The application of this non-biodegradable product is increasing rapidly and the trouble is how to manage the plasticwaste. Dumping of waste materials (like waste plastic bag) is a danger and has become a grave trouble in India, especially in city limits in terms of its abuse, its discarding causes the obstruction of drains, increased soil infertility and affected aesthetics etc. The apparent disposal of plastic wastes by burning will cause the ecological pollution (Allen, 2006). Also, the disposed waste plastic materials do not undergo bio-decay, thus they are either ground filled or get accumulated. Thus, they pollute the earth and the surrounding atmosphere. Any scheme that can utilize this waste plastic for useful intention should definitely be promoted AGGREGATES AND AGGREGATE GRADATION Aggregates play a extremely vital task in providing strength to SMA mix as they contribute a superior part. It contains 70-80% of coarse aggregate of the total mix. The superior proportion of the coarse aggregate in the blend form a skeleton-kind configuration providing a better aggregate-to-aggregate contact between the aggregate particles ensuing in good shear strength and elevated resistance to rutting failure. Brown and Haddock (1997) have remarked that since the strength of SMA relies deeply on the aggregate-to-aggregate frame, it is vital that the blend to be designed with a strong coarse aggregate skeleton. Assortment of appropriate aggregate gradation is a incredibly important feature for SMA. This gradation must be accordingly selected that the mixture of aggregates will grant adequate void structure, with air voids, voids filled with bitumen (VFB), voids in mineral aggregate (VMA), and voids in the coarse aggregate of the blend. Conventionally, the SMA gradation requirements have been used to ensure an ample coarse aggregate frame. Kumar et al. (2007) have reported to the SMA gradation that follows the rule. The rule indicates that the gradation should contain percentage finer than 4.75 mm IS sieve, 2.36 mm IS sieve and mm IS sieves are respectively 30%, 20% and 10% of total aggregate content MINERAL FILLERS AND STABILIZING ADDITIVES (MODIFIERS) The mineral fillers have a noteworthy impact on the properties of SMA. These fillers boost the stiffness of the bituminous mortar matrix. As per Mogawer and Stuart (1996), these mineral fillers will also lead to an increase in workability, moisture resistance, and gives the editor@iaeme.com

4 Effect of Gradation and Waste Plastic on Performance of Stone Matrix Asphalt (SMA) durability to the SMA. These fillers will also cause the reduction of the drain down of the SMA mix at some stage in construction, which intern improves the durability of the SMA mix by maintaining the quantity of binder initially applied in the blend. The SMA which is a gap graded mix, may permit the asphalt binder and the mineral filler to drain when the blend is warm during stockpiling, shipping and placing in position. Hence a modifier or a stabilizer is used to avert this drain-down. Mineral fibers and Cellulose are widely used as stabilizers in Europe whereas polymers are used to lesser degree (Kandhal, P. S, 2007). Fibers stiffen the binder through absorption and resulting in the formation of a fiber network. Polymers stiffen the fiber through various mechanisms depending on the polymer and method of addition. 2. SELECTION OF GRADATION Aggregate mix gradation is one of the most important properties of an aggregate. It affects almost all the significant properties of bituminous mix counting, stability, durability, stiffness, permeability, workability, fatigue resistance, skid resistance and resistance to moisture damage (Ibrahim, 2005). Hence, gradation is a most important consideration in bituminous mix design. Specifications used by most agencies place limits on aggregate gradations that can be used in bituminous mix. Theoretically, it seems rational that the superlative gradation for bituminous mix is the one that gives the densest particle packing. The gradations having utmost compactness provide augmented stability through inter-particle connections and minimized voids in the mineral aggregates. Though, there must be enough air-void space to allow enough asphalt-binder to be penetrated to certify durability of the mix, while still allowing some air-space in the mix to allow secondary-compaction and to shun the problems like bleeding, rutting, etc. A generally used equation to portray a maximum-density gradation discovered by Fuller and Thompson (1997) was used in the present work. By keeping the Fuller's n value as constant i.e., 0.45, maximum bulk density is obtained and hence this value corresponds to increase in fine aggregate proportion, which may in turn cause bleeding during summer due to high binder content in SMA. Therefore it should be noted that n value should vary proportionately in SMA Mix so that fine aggregate proportion in SMA Mix is not more than 30%. Table 1 gives the Bulk Density used in various countries based on Gradation. Table 1 Bulk Density values used in various countries based on Gradation Sieve % Passing Sizes AASHTO MORT&H (India) (mm) (America) 19mm 13mm China Australia Europe Germany _ _ 16.0 _ _ _ _ _ _ editor@iaeme.com

5 % Passing Mithanthaya I.R, Shriram Marathe and Ravi Shankar A.U _ 9-14 _ Bulk Density (g/cc) MATERIALS AND METHODOLOGY An attempt is made to study the performance of SMA by adding adequate proportions of waste plastic to the mix (dry process) and comparison is made between Indian and Chinese gradation. The requirements of SMA Mix, as specified by the Ministry of Road Transport and Highways, Government of India (MoRT&H, 2009) are given in Table 2 is considered for the present study. Table 2 SMA Mix Requirements Mix Design Parameters Requirement Air Void Content, % 4.0 Bitumen Content, % 5.8 min. Voids in Mineral Aggregates (VMA), % 17 min. Asphalt draindown, % (AASHTO T 305) 0.3 max MATERIALS The bitumen of VG-10 grade with specific gravity of 1.00 was used in the present study. The coarse aggregates consisting of crushed rock retained on 2.36 mm, and fine aggregates (2.36mm down size sieve and retained 75 microns IS sieve) consisting of 100 per cent stonecrushed aggregates from local plant from crushing operations were used. The aggregates were properly washed, hard, clean, fairly cubical, durable, and free from the presence of any type of organic or other possible deleterious substances. As the bulk unit-weight was found to be highest for Indian and Chinese gradation (as shown in Table 1), these Aggregate Gradations are adopted. The aggregate gradation curves for Indian and Chinese gradation used are shown in Fig 2 and 3. Lower Limit Upper Limit Adopted IS Sieve size (mm), Log scale Figure 2 Aggregate Gradation curve for SMA Mix ( Chinese Gradation) editor@iaeme.com

6 % Passing Effect of Gradation and Waste Plastic on Performance of Stone Matrix Asphalt (SMA) Lower Limit Upper Limit Adopted IS Sieve size (mm), Log scale Figure 3 Aggregate Gradation curve for SMA Mix ( Indian Gradation) The stone crushed dust and limes were used as mineral filler materials in the present investigations. Out of the 10% filler, 8% is stone dust (passing through 75µm) and 2% is lime powder. The modified shredded form the waste plastics (processed) procured from the garbage were used as Modifiers or stabilizing additives in SMA which come under the category of plastomeric thermoplastic as per IRC:SP: The plastic wastes utilized in the current study were obtained from K. K plastics, Bengaluru. The specific gravity of supplied waste plastic as specified by the suppliers was found to be METHODOLOGY The procedures used for finding out the Optimum Bitumen Content (OBC), Optimum Plastic Content (OPC), % Drain down and Rut depth characteristics of SMA by adding adequate proportions of waste plastic using dry process are briefly explained in the subsequent subsections Marshall Stability Test In the present study, the Marshall s method of mix design (ASTM D-1559) was adopted. The test specimens were prepared at varied percentage of bituminous binder starting from 5.0% till 7.0% by weight of aggregates (with 0.5% variation). For preparing samples with each percentage of bitumen, 4%, 6%, and 8% for Indian Gradation, and 6%, 8%, and 10% for Chinese Gradation shredded plastic wastes were added to obtain the required number of samples for testing. The major Marshall parameters like Voids in Mineral Aggregates (VMA), Voids in Total Mix (Vv), Voids Filled with Bitumen (VFB), and Marshall-Quotient, are obtained from Marshal Stability test and are compared with the specification( IRC:SP:79, 2008) values to check whether they are within specified limits. All these parameters are plotted against Bitumen content, and the Optimum Binder Content (OBC) was established. All the properties are evaluated from the test results for different percentage of plastic used. For every mix 3 samples were prepared and the test results indicate the average value of the tests Drain down Test The drain down test is more considerable for SMA mix than for conventional dense-graded asphaltic mixtures. The test procedure developed for this intention by AASHTO T305 (2000) editor@iaeme.com

7 Mithanthaya I.R, Shriram Marathe and Ravi Shankar A.U It is awaited to imitate the conditions that the SMA mix is likely to come upon as it is formed, stored, transported, and positioned. Drain down is considered designate as that segment of the mix (fines and bituminous binder) that disconnects itself from the section as a whole and flows descending through the blend. The test must be conducted at an anticipated manufacture temperature and must suit the specified highest drain down of 0.30%. The test was conducted as per the guidelines given in ASTM D 6390 on loose mixtures at the OBC (optimum binder content) with different waste plastic contents for both Indian and Chinese gradations, to check whether that the bituminous binder-draining behavior of the produced SMA blends to be within the desirable limits i.e. 0.30%. It also provides a measure of the drain down potential of SMA mixture, produced in the field Rutting Test The rutting behavior were studied the help of Immersion Wheel Tracking Device (IWTD) indicated in Fig 4. The IWTD consists of a loaded wheel and 600mm x 200mm x 50mm mould in which the test sample of SMA placed. The sample was firmly restrained on all faces and positioned on a platform. The device is fitted with a reciprocating device with a motor to furnish the wheel to-and-fro voyage up to 600 mm. The stress from the tyre pressure of wheel pertained on the SMA sample was 0.68 N/mm 2. Two Linear Variable Differential Transducers(LVDTs) are set on each side of the wheel to record the mid-point deflection i.e., depth of impression. The slabs were cast at OBC (i.e. 5.75% for Chinese gradation and 5.8% for Indian gradation) and with Optimum Plastic Content (i.e. 8% for Chinese gradation and 6%for Indian gradation).the value of theoretical bulk density corresponds to 7% air voids was noted. The quantity of aggregates essential to prepare rutting sample were taken according to the adopted gradation using the unit weight value and volume of mould (6000 cm 3 ). Figure 4 Immersion Wheel Tracking Device for Rutting test 5. TEST RESULTS & DISCUSSION 5.1. MARSHALL STABILITY TEST From the Marshall Stability test results, the optimum bitumen content (OBC) for Chinese gradation at 4% air voids with addition of 6%, 8% and 10% waste plastic respectively was found to be 6.0%, 5.75% and 5.7% by weight of aggregates and that for Indian gradation with editor@iaeme.com

8 Effect of Gradation and Waste Plastic on Performance of Stone Matrix Asphalt (SMA) addition of 4%, 6% and 8% waste plastic respectively was 5.9%, 5.8% and 5.33% by weight of aggregates (shown in Fig 5). (ii) Indian Gradation (i) Chinese Gradation Figure 5 Relation between Air Voids and Bitumen Content For the Chinese Gradation the maximum Marshall Stability value was found to be 18 kn for 8% plastic and that of Indian Gradation was found to be 16kN for 6% plastic content. Moreover it is also observed that as the plastic content increases correspondingly OBC decreases for both the gradations. The results were indicated in Fig 6. Thus, it is observed that Marshall Stability value for Chinese mix is 13% more than that of Indian mix. (i) Chinese Gradation (ii) Indian Gradation Figure 6 Relation between Marshall Stability and Bitumen Content The relationship between the bulk density and bitumen content indicated in figure 7 shows that the average density values for both the gradation system are lying in the range of 2.31 g/cc. The maximum density of around 2.34 g/cc is observed in the case of the bitumen content of 5.50% for Chinese gradation at the plastic percentage of 6%. For Indian gradation, the maximum density of 2.35g/cc was observed for a bitumen content of 6.0% with the plastic content of 6.0%. A decreasing trend was observed for the increase in plastic content and also an increase in bitumen content editor@iaeme.com

9 Mithanthaya I.R, Shriram Marathe and Ravi Shankar A.U (i) Chinese Gradation (ii) Indian Gradation Figure 7 Relation between Bulk Density and Bitumen Content The relationship between the Marshall flow value with bitumen content is indicated in figure 8 which shows that the flow value gradually increases for any increase in bitumen content. For Chinese gradation, the mix containing 10% plastic content had shown the maximum flow value and for Indian gradation, for 6% of plastic had shown the maximum flow value. (i) Chinese Gradation (ii) Indian Gradation Figure 8 Relation between Flow value and Bitumen Content The relationship between the VFB value with bitumen content is indicated in figure 9 which shows that the value gradually increases for an increase in bitumen content for all the mixes. The VFB values for Chinese gradation and for Indian gradation were almost same editor@iaeme.com

10 Effect of Gradation and Waste Plastic on Performance of Stone Matrix Asphalt (SMA) (i) Chinese Gradation (ii) Indian Gradation Figure 9 Relation between VFB and Bitumen Content 5.2. DRAINDOWN TEST From the figure 10, it is observed that without waste plastic, the drain down was found to be maximum i.e., greater than 0.3%, which exceeds the specified limits. When the waste plastic is added to SMA, it can be observed that a decrease in the drain down value for the test results of both Chinese and Indian gradation. Thus, as the waste plastic content increases correspondingly drain down decreases. (i) Chinese Gradation (ii) Indian Gradation Figure 10 Drain Down test results 5.3. RUTTING TEST The maximum rutting depth was determined by Immersion Wheel Tracking Device (IWTD). The deformation of the SMA mixes at 10,000 passes for Chinese gradation with 5.75 per-cent OBC and 8 per-cent optimum plastic content (OPC) was found to be 3.3 mm. The result for Indian gradation with 5.80 per-cent OBC and 6.0 per-cent OPC was found to be 5.8 mm. As observed in the figure 11, rutting depth was found to be lower for Chinese gradation when compared with that of Chinese gradation. By comparing the results of both gradations, the observed rutting depth for Indian gradation was found to be 42 per-cent greater than that of Chinese gradation editor@iaeme.com

11 Rutting Depth (mm) Mithanthaya I.R, Shriram Marathe and Ravi Shankar A.U China MoRT&H No. of Passes Figure 11 Relation between Rutting Depth and No. of passes 6. CONCLUSIONS On the source of investigation on the test end results gained in the current study, the following conclusions are drawn. 1. The Optimum Bitumen Content (OBC) at 4 per-cent air voids for Chinese gradation was found to be 6 per-cent, 5.75per-cent and 5.70per-cent with the addition of 6per-cent, 8per-cent and 10per-cent waste plastic and that for Indian Gradation for 4per-cent, 6per-cent and 8per-cent waste plastic was found to be 5.9per-cent, 5.8per-cent and 5.3per-cent respectively. 2. As the waste plastic content increases, OBC value decreases for both for the Chinese and Indian gradation. 3. In the case of Chinese gradation, the Marshall Stability values with 8.0 per-cent waste plastic was much higher i.e. 18 kn while compared to other blends. Similarly, for Indian gradation with 6.0 per-cent waste plastic was found to be 16kN was the greatest value. Thus, it can be stated that Marshall Stability value for Chinese blend is 13% greater when compared to Indian blend. 4. The drain down value for Chinese gradation without the use of waste plastic was found to be 0.39 per-cent at OBC. The adding of waste plastic to SMA blend the drain down value decreases, making the mix more stable. A similar trend was observed in the case of Indian gradation exclusive of waste plastic the drain down was found to be 0.64 per-cent. Further addition of waste plastic reduced drain down. Also, it was found that drain down value for Indian gradation was slightly higher than that of Chinese gradation. 5. The rutting test results revealed that the Chinese gradation with 5.75 per-cent Optimum Binder Content (OBC) and 8.0 per-cent optimum plastic content ( OPC) rutting depth was found to be 3.3 mm and that of Indian (MoRT&H) gradation with 5.8% OBC and 6% OPC, it was found to be 5.8mm. It was also observed that rutting depth was found to be 42% higher for Indian gradation editor@iaeme.com

12 Effect of Gradation and Waste Plastic on Performance of Stone Matrix Asphalt (SMA) compared to that of Chinese gradation. Hence, the Chinese gradation is better than the Indian gradation. 6. The Marshall Stability value was found to be greater for Chinese gradation compared to Indian gradation. Drain down and rutting values found to be much lower for Chinese gradation as compared to Indian gradation. It can be concluded that Chinese gradation is better than Indian gradation. Hence re-looking on Indian gradation is necessary to improve its performance. REFERENCES [1] National Asphalt Pavement Association (NAPA), Designing and Constructing SMA Mixtures State-of-the Practice, (2002) Quality Improvement Series 122, March [2] Kandhal, P. S, Specifications for Stone Matrix Asphalt Document No. 3,(2007), Indian Highways, Vol. 35, No. 2, February 2007, Indian Roads Congress, p [3] Kamaraj, C, Kumar, G, Sharma, G, Jain, P.K and Babu, V. (2004). Laboratory Studies on the Behavior of Stone Matrix Asphalt VIS-À-VIS Dense Graded Bituminous Mixes using Natural Rubber Powder (Wet Process). Highway Research Bulletin, No 71, Indian Roads Congress, New Delhi, p [4] Kamaraj, C, Jain, P. K, Sood, V. K and Sikdar, P. K, (2006), Design of stone matrix asphalt using different stabilizing additives. Journal of the Indian Roads Congress, Volume 67-1, April- June 2006, p [5] Ibrahim, M. A, (2005), Laboratory comparison study for the use of stone matrix asphalt in hot weather climates Construction and Building Materials 20, p [6] AASHTO T 283, Resistance of Compacted Asphalt Mixtures to Moisture Induced Damage. [7] Allen, G. K., (2006) Problems of Stone Mastic Asphalt Use in North Queensland, A Dissertation Submitted to the Faculty of Engineering and Surveying, University of Southern Queensland, November, [8] ASTM C 29, Bulk Density (Unit Weight) and Voids in Aggregate. [9] ASTM D 3625 (1996), Standard Practice for Effect of Water on Bituminous- Coated Aggregate Using Boiling Water. [10] ASTM D , Standard Test Method for Determination of Draindown Characteristics in Uncompacted Asphalt Mixtures. [11] Ganesh, K, Jagadeesh, H. S, Sathyamurty, R, (2010), Design of Automatic Immersion Wheel Tracking Equipment to Measure the Rutting Characteristics of Btuminous Mixes with Plain and Modified Binders, Highway Research Journal, Highway Research Board, January-June 2010, p [12] IRC:SP: ,Tentative specifications for Stone Matrix Asphalt, Published by Indian Roads Congress, [13] Standard Specifications for Road, Bridge and Municipal Construction (2000), Published by Washington State Department of Transportation, USA. [14] Kumar Pawan, Chandra Satish, and Bose Sunil (2007), Laboratory investigations on SMA mixes with different additives, International Journal of Pavement Engineering, Vol. 8, No. 1, March 2007, editor@iaeme.com