SOIL IMPROVEMENT USING WASTE TIRE CHIPS

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1 International Journal of Civil Engineering and Technology (IJCIET) Volume 9, Issue 8, August 2018, pp , Article ID: IJCIET_09_08_135 Available online at ISSN Print: and ISSN Online: IAEME Publication Scopus Indexed SOIL IMPROVEMENT USING WASTE TIRE CHIPS Khalida Ahmed Daud Department of Architectural Engineering, Al-Nahrain University, Baghdad, Iraq ABSTRACT Huge quantities of waste tires can be beneficially used in earth work projects such as retaining structures backfills and roadway embankments. This is a new soil stabilization technique which can be essentially used to reduce the quantities of waste. This can be done through producing serviceable material from non-serviceable waste materials. The main task of the present work is to estimate the mechanical properties and behavior of waste tire and their blends with soils. An experimental study was carried out to survey the influence of using waste tire on shear attribute or characteristics, deformability and compressibility. The obtained results show that the soil-tirechip mixtures have analogous response to pure soils. But the soil tire blends are more compressible and also require large deformation to gain their ultimate shear strength. Moreover, the trials have obviously exhibited a significant development in shear. The increase in shear strength for sandy soil was primarily caused by the increase in friction angle. While, the results for sandy silt tire chip blends indicate that the angle of internal friction is essentially independent of the tire chip content. In this case, there is noticeable increase in cohesion which cause increase in shear strength. Key words: sandy silt, soilblend, compressibility, shear strength, tirechips. Cite this Article: Khalida Ahmed Daud, Soil Improvement using Waste Tire Chips. International Journal of Civil Engineering and Technology, 9(8), 2018, pp INTRODUCTION In Iraq, large quantities of tires are stockpiled due to increasing in the number of cars passing on their roads. Thus, stockpiles of waste tires will continually increase, unless new techniques are developed to beneficially reuse of recycle tire [Singh and Vinot, (2011)]. Many issues or problems canarise from increasing waste tire volumes therefore, it is necessary to find economical and perpetual applications. These applications of waste tires in various forms (shreds, chips or crumbs) has been recently developed in treating soil for different geotechnical applications such as retaining structures, earth embankments and foundation beds [Singh and Mittal (2014)]. Therefore, the use of waste materials when blended with soil has become more interesting due to the lack of natural materials and increasing the cost of waste disposal. However, the enlargement use of waste tires in solving geotechnical problems, leads to a need for further carrying studies on the response of tire soil blends [Humphrey et. al editor@iaeme.com

2 Soil Improvement using Waste Tire Chips (1993)]. Several researchers have carried out laboratory and field investigations especially with cohesionless soil to study the use of waste tires for soil stabilization, bearing capacity improvement and for reduction of settlement. The previous studies employing tire chips focus on investigating the mechanical characteristics of tire chips and sand-tire chipblends (Humphrey et al. 1993, Edil and Bosscher 1994, Foose et al. 1996). While these studies have shown that soil-tire chip blends have enhanced mechanical properties, using select soil like pure sand increases the cost of construction, which limited the application of using tire chips as a waste material. Therefore, there is a need to trace the behavior of soil-tire blends made with a significant fraction of fines [Tatlisoz et. al. (1997) & K.N.Kadhim and Ghufran,2016]. The present study objective was to evaluate the shear strength and compressibility of soiltire chip blends made with sand and soil with a significant fraction of fines.direct sheartestswere carried outon sandy silt-tire chip blends and sand-tirechip blends to obtain their shear strength parameters. Compression tests were conducted on tire chips mixed with pure sand and sandy-silt to acquaint the immediate compression. 2. EXPERIMENTAL PROGRAM 2.1. Soils and Tire Chips To achieve the purpose of this paper, medium sandy and sandy silt soil samples were brought from south of Iraq(holy Karbala city). Samples were taken from shallow depth While the waste tire rubber used in this research are irregularly shaped, plate-like particles of maximum dimensions less than 3.5 mm and specific gravity of The average compacted density is 750 kg/m 3. Limited information are obtainable on the shear strength of tire chips. From previous studies, the shear strength of tire chips is found to be dependent on the size and shape of the chips, internal friction angles and cohesion. The internal friction of tire chips were found to vary from 19 o to 26 o, while cohesion values vary from 4.3kPa to 11.5kPa [Singh and Mittal (2014) ] Testing Program Soils Classification On the basis of the results of classification tests, the soils were classified. Firstly, the sandy soil was categorized as medium uniform graded sand (SP) based on the USCS (Unified Soil Classification System). And secondly, the sandy silt soil was classified as medium sandy silt(ml) according to the same classification system. The grain size distribution curves of investigated soils are presented in Figure 1, while the index properties and compaction characteristics of these soils are listed in Table 1. Table 1 Index properties of the soils Property Sandy soil Sandy silt soil Specific gravity Minimum dry density (kn/m 3 ) 14.5 Maximum dry density (kn/m 3 ) Uniformity coefficient, C u 1.96 Curvature coefficient, C c 0.84 Liquid limit 18 Plastic limit 15 Plasticity index 3 Optimum water content % editor@iaeme.com

3 Khalida Ahmed Daud Figure 1 Particle size distribution curve Effect on Unit Weight Samples of soil-tire chip mixtures were compacted to determine the relevance between tire chip content and unit weight. Before compaction, the sandy silt and sand were mashed or grinded until they pass the 19 mm sieve. Five different mixtures were prepared, containing respectively 0, 10, 20, 30and 40% by weight of soil. The required amounts of soil and tire chip were blended together under dry conditions and enclosing that the tire chips were distributed uniformly and randomly in the blends. The sandy silt samples were blended with water to acquire a water content of 5% dry of optimum in order to have a stiff mixture as shown in table 1. While no water was added to the sand and using procedure described in ASTM standard test methods using standard effort D698in order to obtain the compaction results [Ediland Bosscher (1994), Humphrey and Sandford (1993)]. Test results on the soils are given in Fig. 2. The unit weight of the soil-tire chip blends reduced as the tire chip content enlarges. This is due to lower specific gravity of tire chips and there is no significant influence on the variation of the optimum moisture content. Figure 2 Relationship between Unit weight and tire chips content editor@iaeme.com

4 Soil Improvement using Waste Tire Chips From the previous figure, it is obvious that the soil tire mixtures are lightweight materials. This means that utilizing blends of soil and tire chip as backfill materials leads to reduce the structural components effect on the retaining walls.the used chips chemical components are mix or blend of two types; natural and artificial rubber. An additional component exists in the chips such as carbon, sulfur, polymers, oil, fabrics, and belt materials Effect on direct shear Direct shear laboratory tests were conducted on the soils-tire blends using ASTM Test Method for Direct Shear TestD The blended materials were carefully transferred to the shear box in three layers to avoid any loosing of the chips. Five normal stresses of 25, 50, 57,011 and 125 kn/m 2 were used. Sandy silt samples were prepared using the compaction methods described earlier, while; the sandy specimens were compacted directly in the shear rings. Ashear rate was kept0.5 mm/min for all tests to obtain a rapid, quasi-undrained condition in the field. The tests were continued until a constant shear stress is recognized [Edil and Bosscher (1994)]. Fig. 3 showed the variation of shear stress horizontal displacement curves obtained for a normal stress of 50 kpa for the sand treated with irregular shape of size 3.5 mm tire chips. From this figure, it is observed that, the initial slope or stiffness of the blended sand is lesser than that of the sand alone,at low shear displacement.but at higher shear displacement, the blended sand shows greater shearing résistance than the pure sand. And this is true for chips content not more than 30%. The behavior of other normal stresses shows similar trends. Therefore, the value of optimum chip content must be defined in which stress development interpretation in soil will be the best. During the implementation of normal stress, there is a primary penetration of sand particles into the tire chips, which is demonstrated as a temporary compression. This compression stress is overcome by adequate shear distortion, after which interaction begins to improve between the sand particles and chips. It is observed that shear resistance improvement may be due to implementation of tire chips into the soil [Foose, G. (1993), Humphrey and Sandford (1993)]. Figure 3 Shear stress horizontal displacement curves Also, during the tests there was a noticeable volume modulation related with the evolution of the shear stress and representative variation of volume modulation curves (at a editor@iaeme.com

5 Khalida Ahmed Daud normal stress of 50 kpa) for the blends of sand with tire chips are given in Fig. 4. This behavior is obvious through pure sand which sprawls after an initial small compression but the mixture are first compress and then dilates as the shear develops. This is because that the tire chip are deformable and this will lead to reduce the sand particle movement around the chip during shearing and at 40% chip content, no dilation was indicated. Figure 4 The relationship between vertical and horizontal displacements of sandy soil tire chips mixture Similar trends of results were obtained for the direct shear tests on the blends of sandy silt-tire chip. The blends have greater strength than soil alone, moreover, greater displacement are needed to reach ultimate strength for blends of sandy silt tire chip. Major difference between the behavior of sand tire chip and sandy silt tire chips blends is the shape of failure envelope as shown in Fig 5 and 6. The increase in shear strength for sandy soil was primarily caused by the increase in friction angle as the chip contents increases. While, the results for blends of sandy silt tire chip indicate that the angle of internal friction is independent of the tire chip content. The enlargement in strength of sandy silt tire chips blends obtained by increasing in the tire chip content are due to the primarily increase in soil cohesion not in its friction angle [Foose et. al. (1996)]. Figure 5 Shear strength envelopes for sand tire chips mixtures editor@iaeme.com

6 Soil Improvement using Waste Tire Chips Figure 6 Shear strength envelopes for sandy silt tire chips mixtures Compression Tests One-dimensional compression of soil-tire chip blends was obtained under laterally constrained conditions. Samples were prepared using the compaction process used in the unit weight evaluation in the proceeding sections. And then they were compressed in the molds of compaction. Vertical deformation was recorded at normal stress intervals of 5 kn/m 2. Prior to compression, a seating stress of 6 kn/m 2 was applied. The maximum normal stress applied to the specimens was 100 kn/m 2.The normal stress was increased at 5 kn/m 2 /min. till the maximum stress was reached. After that, the stress was released at the similar rate to reach the seating stress. Fig. 7 shows the relationship between vertical strains and vertical stress for sand-tire chip and sandy silt-tire chip blends containing 30% tire chips. The shape of the compression curves is the same regardless of the soil type or the tire chip percentage or content. For all soil-tire chip mixtures, the strain produced at the end of loading cycle is named the "static strain". Static strains for the blends are shown in Fig. 8. The static strain increases proportionally with tire chip content, which also suggests that compressibility is governed primarily by tire chips, and not soil kind. However, the sandy-tire chips blends do compress slightly more than sandy silt-tire chip ones. Therefore, sandy silt-tire chip blends when used in backfills are less compressible than backfills comprise sand-tire chips blends [Foose, (1993), Tatlisoz (1996)] editor@iaeme.com

7 Khalida Ahmed Daud Figure 7 Vertical stress strain curves obtained from compression test Figure 8 Vertical strain tire chips content relationship obtained from compression test Compressibility modulus C m can be used to describe the compressibility of blends of soiltire chip and to evaluate the settlement or deflection of soil-tire chip. This modulus is calculated from the inclination of the initial compression curve, or from the cyclic loading curves. For each blends, the largest reduction in compressibility recognized when the chips content increases as shown in Fig 9. Figure 9 Compressibility modulus variation with tire chips content at 100 kpa 3. CONCLUSIONS Based on the present study research, the following conclusions are obtained: 1-The study has showed the advantage of reusing tire chips to treat sandy soil and sandy silt soil. 2-The maximum unit weight is recognized to be decreased with the increases of the percentage of chips. This attributed to the lightweight nature of tire waste. 3- The increase in shear strength for sandy soil was primarily caused by the increase in friction angle. While, the results for sandy silt tire chip blends indicate that the angle of internal friction is essentially independent of the tire chip content editor@iaeme.com

8 Soil Improvement using Waste Tire Chips 4-Test results show that the soil-tirechip mixtures have a similar behavior of soils alone, but are higher compressible and also need larger deformation to gain their ultimate shear strength. 5-For each blends, the largest reduction in compressibility recognized when the chips content increases. The compressibility modulus for the sandy-silt blends is obviously lower than for blends made with sand blends REFERENCES [1] Edil, T. and Bosscher, P. (1994), "Engineering Properties of Tire Chips and Soil Mixtures," Geotechnical Testing Journal, ASTM, Vol. 17, No.4, pp [2] Foose, G. (1993), "Shear Strength of Sand Reinforced with Shredded Waste Tires," MS Thesis, Dept. of Civil and Environmental Engineering, University of Wisconsin-Madison. [3] Foose, G., Benson, C., and Bosscher, P. (1996), "Sand Reinforced with Shredded Waste Tires,"Journal of Geotechnical Engineering, ASCE, Vol. 122, No.9, pp [4] Humphrey, D. and Sandford, T. (1993), "Tire Chips as Lightweight Subgrade Fill and Retaining Wall Backfill," Proc. Symp.on Recovery and Effective Reuse of Discarded, Materials and By-Products for Construction of Highway Facilities, Federal Highway Administration, Denver, pp [5] Humphrey, D., Sandford, T., Cribbs, M., and Manion, W. (1993), "Shear Strength and Compressibility of Tire Chips for Use as Retaining Wall Backfill," TransportationResearchRecord,N o. 1422,TransportationResearchBoard, WashingtonD C, pp [6] Kadhim Naief Kadhim and Ghufran A.( The Geotechnical Maps For Gypsum By Using Gis For Najaf City (Najaf - Iraq). (IJCIET), Volume 7, Issue 4, July-August 2016, pp [7] Singh, B. and Vinot, V. (2011)," Influence of Waste Tire Chips on Strength Characteristics of Soils", Journal of Civil Engineering and Architecture, Vol. 5, No.9, pp [8] Singh, M. and Mittal, AS. (2014)," A review On The Soil Stabilization With Waste Materials ", International Journal of Engineering Research and Applications, National Conference on Advances in Engineering and Technology,AET-29 th March, pp [9] Tatlisoz, N. (1996), "Using Tire Chips in Earthen Structures," M.Sc. Thesis, Dept. of Civiland Environmental Engineering, University of Wisconsin-Madison. [10] Tatlisoz, N., Benson, C. H. and Edil, T. B. (1997), "Effect of Fines on Mechanical properties of Soil- Tire Chips Mixtures," Testing Soil Mixed with Waste or Recycled Materials, ASTM, STP editor@iaeme.com