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A STUDY ON THE INFLUENCE OF PARTICLE CHARACTERISTICS ON SHEAR STRENGTH BEHAVIOR OF QUARRY DUST

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A STUDY ON THE INFLUENCE OF PARTICLE CHARACTERISTICS ON SHEAR STRENGTH BEHAVIOR OF QUARRY DUST
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    Proceedings of Indian Geotechnical Conference  December 22-24,2013, Roorkee   A STUDY ON THE INFLUENCE OF PARTICLE CHARACTERISTICS ON SHEAR STRENGTH BEHAVIOR OF QUARRY DUST K. Koustuvee , Post Graduate Student, Assam Engineering College, kumarikoustuvee@gmail.com A. Sridharan , Honorary Scientist, Indian National Science Academy, Formerly, Professor, IISC Bangalore, sridharanasuri@yahoo.com K. Chinmoy ,   Under Graduate Student, Assam Engineering College D. Rahul ,   Under Graduate Student, Assam Engineering College, rahuld.das@gmail.com   C. Malaya , Assistant Professor, Assam Engineering College, gogoi_chetia@yahoo.co.in ABSTRACT:  Quarry dust which is a waste product produced during crushing of stones to obtain aggregates can  be used in geotechnical applications as a promising substitute for sand. The geotechnical characterization of quarry dust can lead to practicable solutions for its large-scale utilization. With this in view, experiments were conducted on three locally available quarry dusts using direct shear test to understand their shear strength behavior. The  present study attempts to understand the influence of the particle characteristics on the shear strength of quarry dust. It must be noted that there are limited studies available in the literature on the influence of particle size and shape on the shear strength behavior of quarry dust. The study indicates that the particle characteristics have  positive effect on the shear strength of quarry dust. INTRODUCTION  Quarry dust or crusher dust is produced as solid wastes mainly during crushing operations. It constitutes 20-25 % of the output of each rubble crusher unit and about 200 million tones of quarry  by-products are being generated each year in India [1]. Disposing of this waste adds both economic and environmental costs to the quarrying process [2]. However, the use of quarry dust in geotechnical applications is economically  beneficial and environmentally advantageous [1]. Many researchers have used quarry dust in geotechnical applications to improve the geotechnical properties of soil. Soosan et al. (2001) [3] observed that the quarry dust can be used as a substitute for sand to improve the properties of lateritic soil. Soosan et al. (2005) [1] reported the improvements in the compaction characteristics and California Bearing Ratio of soils including  problematic soils like marine clays by addition of quarry dust. Nwaiwu et al. (2012) [4] have reported that the quarry dust can effectively be used for road construction purposes involving black cotton soil. The study of shear strength behaviour of quarry dust is important to use it as a geotechnical material. There are different factors that may have influence on the shear strength behaviour of quarry dust. It must be noted that there are very few studies related to the shear behaviour of quarry dust. Therefore, the present study investigates the shear strength behaviour of dust examining the influence of particle size, and shape on the shear strength of quarry dust. The study indicates that the grain size and shape have significant influence on the shear behavior of quarry dust. EXPERIMENTAL INVESTIGATIONS Four cohesionless materials were used in this study, which include a locally available sandy soil (denoted as S) and three quarry dusts (denoted as D1, D2 and D1sS). Sand and quarry dust have been characterized for its specific gravity and grain size distribution by following the guidelines provided in the literature [5,6]. According to USCS [7] all the samples are poorly graded (SP). The results of these characterizations are presented in Table 1. In the Table 1, SL GSDC  represents the slope of the grain size distribution curve (GSDC) and it is determined by using the Eq. 1. From the quarry dust sample, D1 a new dust sample has been Page 1  of 5      K. Koustuvee, A. Sridharan, K. Chinmoy, D. Rahul & C. Malaya  prepared with similar grain size distribution as the sand sample, S and this new dust sample has been designated as D1sS. The grain size distribution curves of the quarry dust samples and sand are shown in Fig.1. SL GSDC   = (60 % - 10 %)/(  Log D 60 -  Log D 10 ) (1) where,  D 60   = a size in mm that 60% of the particles are finer than that size; and  D 10   = a size in mm that 10% of the particles are finer than that size. Shape and mineralogical characterization of the samples were carried out from the petrographical images. Petrographical images (Figs. 2-3) indicate that the main mineral present in the samples is quartz. The shape of the sand particles are mainly rounded to subrounded whereas the dust particles are mostly angular to subangular. The direct shear tests [8] were carried out on dry dust samples and sand under consolidated drained conditions to obtain the shear parameters of the samples. A strain rate of 1.25 mm/min was used while  performing the direct shear test on all the quarry dust and sand samples. Fig. 1  Grain size distribution curves of D1, D2, S and D1sS Fig. 2  Petrographical image of sand, S Fig.  3 Petrographical image of quarry dust, D1 Table 1  Physical properties and classification of the samples used in this study 0.010.11100102030405060708090100110      %   f   i  n  e  r Grain size (mm)  D1 D2 S D1sS Property Soil Quarry dust S D1 D2 D1sS Specific Gravity 2.67 2.68 2.62 2.67 Particle Size Characteristics (%) Sand (4.75-0.075 mm) Coarse Sand (4.75-2 mm) 2.9 1.2 20.1 2.9 Medium Sand (2-0.425 mm) 54.9 38.5 37.4 54.9 Fine Sand (0.425-0.075 mm) 40.6 49.1 36.8 40.6 Silt (0.075-0.002 mm) 1.6 11.2 5.7 1.6 C c  1.1 1.09 2.3 1.1 C u  2.7 5.8 8.3 2.7 SL GSDC  1.2 0.66 0.54 1.2 USCS Classification SP SP SP SP Page 2  of 5       A study on the influence of particle characteristics on shear strength behavior of quarry dust RESULTS AND DISCUSSION The direct shear tests were performed on quarry dust (D1, D2 and D1sS) and sand (S) samples in the dry condition in a density range of 1.24 gm/cm 3  to 1.30 gm/cm 3 . The displacement vs. shear stress  plots of different samples for normal stress of o.5 kg/cm 2 , 1.0 kg/cm 2  and 1.5 kg/cm 2 have been obtained. Figures 4-5 show the displacement vs. shear stress plots for the quarry dust samples D1 and D2 at strain rate 1.25 mm/min. similar trends have been observed for both the quarry dust samples. Figure 6 shows the displacement vs. shear stress plots for the samples D1sS and S at strain rate 1.25 mm/min. It is clear from the figure that the quarry dust sample exhibits more shear resistance at failure than the sand sample for all the normal stresses. However, the shear displacement at failure is more for S than D1sS. These differences may be due to the difference in the shape of the samples. It must be mentioned that the grain size distribution of D1sS and S are similar. The maximum shear stress, τ  max  values obtained at different normal stresses for all the samples used in this study are presented in the Table 2 along with the shear displacements, SD corresponding to τ  max . The σ  n  vs. τ  max  plots are shown in the Fig. 7 for the samples tested in this study. The Ф  values obtained from these figures have been shown in the Table 2. Fig. 4 Displacement vs shear stress plots for D1 Fig. 5  Displacement vs shear stress plots for D2 0.00.51.01.52.02.53.03.54.04.55.05.56.06.57.00.00.20.40.60.81.01.21.4      S   h  e  a  r  s   t  r  e  s  s ,      (   k  g   /  c  m    2    ) Shear displacement (mm) Quarry dust D1sS  n  = 0.5 kg/cm 2   n  = 1.0 kg/cm 2   n  = 1.5 kg/cm 2 Sand S  n  = 0.5 kg/cm 2   n  = 1.0 kg/cm 2   n  = 1.5 kg/cm 2   Fig. 6 Displacement vs shear stress plots for D1sS and S 0.00.20.40.60.81.01.21.41.60.00.20.40.60.81.01.21.4      M   a   x   i   m   u   m    s   h   e   a   r   s   t   r   e   s   s ,      m   a   x    (   k   g   /   m    2    ) Normal stress, n  (kg/cm 2 )  D1   D2 D1sS   S = 42.3 0  , = 39.8 0  = 39.2 0 , = 33.9 0   Fig. 7  Normal stress vs shear stress plots for D1, D2, D1sS and S 0.00.51.01.52.02.53.03.54.04.55.00.00.20.40.60.81.01.21.4      S   h  e  a  r  s   t  r  e  s  s ,      (   k  g   /  c  m    2    ) Shear displacement (mm)   n  = o.5 kg/cm 2   n  = 1.0 kg/cm 2   n  = 1.5 kg/cm 2 0.00.51.01.52.02.53.03.54.04.55.00.00.20.40.60.81.01.21.4      S   h  e  a  r  s   t  r  e  s  s ,      (   k  g   /  c  m    2    ) Shear displacement (mm)   n  = o.5 kg/cm 2   n  = 1.0 kg/cm 2   n  = 1.5 kg/cm 2 Page 3  of 5      K. Koustuvee, A. Sridharan, K. Chinmoy, D. Rahul & C. Malaya Table 2  Maximum shear stress, τ max , shear displacement, SD and Φ  values Influence of Grain Size on the Shear Behavior of Dust Figure 8 shows the variation of Ф  value with the coefficient of curvature, C c  of the GSDC of quarry dusts D1, D2 and D1sS. C c  values have been shown in the Table 1. It can be observed from this figure that the Ф  value initially decreases with the increase in the C c  values and then increases with the increase in C c . Figure 9 presents the variation of Ф  value with the uniformity coefficient, C u  of the GSDC of quarry dusts D1, D2 and D1sS. C u  values have been presented in the Table 1. The figure shows that the Ф  value initially increases with the increase in C u  value and then it decreases with the increase in C u  value. The variation of Ф  with the slope of the GSDC, SL GSDC  is shown in the Fig. 10. The figure depicts that the Ф  value of the quarry dust samples initially increases with the increase in the SL GSDC and then it decreases with the increase in SL GSDC . Therefore, from these observations it can be said that the grain size characteristics of quarry dust have significant influence on its shear strength behavior. 0.51.01.52.02.53.036384042      (   d  e  g  r  e  e  s   ) C c   Fig. 8 Variation of Ф with C c   2345678934363840424446      (   d  e  g  r  e  e  s   ) C u   Fig. 9 Variation of Ф with C u   0.50.60.70.80.91.01.11.21.3343638404244      (   d  e  g  r  e  e  s   ) SL GSDC   Fig. 10 Variation of Ф with SL GSDC Sample σ  n τ  max SD Φ   kg/cm kg/cm mm Degree D1 0.5 0.71 2.8 42.3 1.0 0.96 3.6 1.5 1.3 3.8 D2 0.5 0.41 2.8 39.8 1.0 0.75 3.2 1.5 1.3 3.4 1.0 0.89 2.4 D1sS 0.5 0.45 1.6 39.2 1.0 0.88 2.8 1.5 1.2 2.4 S 0.5 0.34 2.8 33.9 1.0 0.69 3.8 1.5 0.99 4.4 Page 4  of 5  
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