International Journal of Applied Engineering Research ISSN 0973-4562 Volume 13, Number 4 (2018) pp. 2068-2071 © Research India Publications. http://www.ripublication.com

Correlation between California Bearing Ratio (CBR) and Dynamic Cone Penetrometer (DCP) for soil from Sincelejo city in Colombia

Fernando Jove Wilches1*, Jhon Jairo Feria Díaz2 and José Rodrigo Hernandez Ávila3 1* Civil Engineer MSc., Land Roads and Pavement Specialist. Associate Professor, Department of Civil Engineering, University of Sucre, Sincelejo, Colombia. 2 Sanitary Engineer, Environmental Sciences MSc. Research Group on Environment and Water (GIMAGUAS), Associate Professor, Department of Civil Engineering, University of Sucre, Sincelejo, Colombia. 3 Civil Engineer, Magister of Structures. Research Group on Environment and Water (GIMAGUAS), Assistant Professor, Department of Civil Engineering, University of Sucre, Sincelejo, Colombia. 1,2,3ORCID ID: : 0000-0002-2080-4036, 0000-0003-1397-1546, 0000-0002-7557-9665 * Corresponding Author

Abstract for studies. A correlation equation was obtained with good adjustment for stimating the CBR based on the DCP [6]. The This research aims at determining a correlation equation between California Bearing Ratio (CBR) and Dynamic Cone test basically consists on penetrating a cone-tipped rod into the ground and recording the accumulated penetration as a mass of Penetrometer (DCP) for soils of Sincelejo city in Colombia 8 kg is dropped from a 575mm height. [7]. DCP test results are allowing to economically and appropriately determine bearing capacity of subgrade soil in pavements design. 46 soils samples represented in a graph where penetration evolution (ordinate) with regards to the number of accumulated blows (abscissa) is from the city’s south were taken for in-situ (DCP) and laboratory (CBR, on unaltered sample) tests. A dispersion recorded. Through this curve, called DCP curve, different layers can be established according to areas of greater or lesser diagram and correlation curve with a determination coefficient resistance to penetration. Additionally, for each layer or zone greater than 80% were developed, i.e., the equation found has of homogeneous resistance characteristics, the slope that a good data representation of the tests carried out. Soil has represents it, is generated within the DCP curve, called the predominant clay characteristics; therefore, it is necessary to project subgrade stabilization works in pavements design. Penetration Index, which defines the degree of resistance of a soil in terms of the depth reached (in mm) for each blow [8]. Key Words: California Bearing Ratio (CBR), Dynamic Cone The Colombian norm adopted a general equation to establish a Penetrometer (DCP), correlation equation, soil characterization. theoretical correlation between penetration by blow (DCP) and CBR, based on an expression recommended by the Corps of Engineers of the United States Army as shown below [9] INTRODUCTION 292 퐶퐵푅 = Equation 1. (퐷퐶푃)1.12 The California Bearing Ratio (CBR) is a way for classifying soil capacity to be used as a subgrade or base material in pavements construction [1]. CBR test measures soil shear Nonetheless, it is convenient to establish an equation that strength under controlled humidity and density conditions. The correlates CBR values with greater precision for each soil, CBR number (or simply called CBR) is obtained as the ratio of depending on the geotechnical characteristics of each region, the unit load required to achieve a certain penetration depth based on in situ DCP tests. within the soil compacted sample at a given moisture content The purpose of this research study was to characterize and find and density, regarding the right unit load to obtain the same an equation that adequately correlates CBR and DCP for fine penetration depth of a standard sample of crushed material [2]. soils from the southern part of Sincelejo city in Colombia, to On the other hand, the Dynamic Cone Penetrometer (DCP) is a provide a low-cost tool to define bearing capacity of subgrade device used to evaluate in-situ resistance of unaltered or soils in pavements design. compacted materials soils [3]. DCP was developed in South

Africa in the 1960s by Dr. D. J. Van Vuuren to simply estimate in-situ support capacity of subgrade materials and layers MATERIALS AND METHODS making up pavement [4], [5]. Subsequently, Kleyn (1975) Soil samples for this study were taken in Sincelejo city, conducted some studies for the Transvaal Road Department Colombia, in the Divino Nino (sector I and II) and in La from South Africa by taking 2000 soil samples approximately

2068 International Journal of Applied Engineering Research ISSN 0973-4562 Volume 13, Number 4 (2018) pp. 2068-2071 © Research India Publications. http://www.ripublication.com

Victoria neighborhoods, located in the southern part of the Table 1. Soil types present in the samples tested in the urban area [8]. 46 random points were selected within the road laboratory network of the area and, the procedure established by the Amount Amount AASHTO USCS American Standard Testing Materials [7] to obtain DCP curve samples (%) samples (%) and Penetration Index of a soil tested in-situ was applied A-4 2.17 SC 4.35 Eight (8) out of the unaltered samples taken were discarded due A-5 4.35 ML 2.17 to defects in cutting or excessive moisture loss at the time of A-6 8.70 MH 28.26 collecting. Correlations were determined from penetration rates A-7-5 41.30 CL 8.70 A-7-6 43.48 CH 56.52 and support ratio values: CBR at 0.1 "CBR at 0.2" and maximum CBR [8]. The California Bearing Ratio (CBR) was obtained for each unaltered sample, following the procedure According to the results and bearing in mind the AASHTO established in the Colombian standards for conducting CBR system, 93.48% of the subgrade material studied is a clay type test [10]. Soils classification was carried out from granulometry soil and 6.52% is silty soil. Nonetheless, according to USCS, tests and liquid and plastic limits from analyzed samples, 65.22% belongs to clay soils of high and low plasticity; 30.43% according to the classification systems of the American to silty soils, high and low plasticity; and 4.35% is clayey sand. Association of State Highway and Transportation Officials In general terms, the soil is clay type in a high percentage of its (AASHTO) and the Unified Soil Classification System composition, with the presence of silts and clayey sands in (USCS). smaller proportions. For this clay soil type, it is necessary to perform stabilization works, especially for its low support For determining the correlation equation, DCP results were capacity when subjected to high humidity conditions and for plotted on the abscissa axis and CBR results on the ordinate the case of high plasticity clays (CH), due to its susceptibility axis to find a scatter plot. Linear regression was applied, and a to undergo volumetric changes before humidity variations. potential type equation was found, using Microsoft Excel software. Table 2 shows the tests results carried out in in-situ and laboratory condition, to define the DCP and CBR of samples

analyzed, respectively. RESULTS AND DISCUSSION

Table 1 shows results of soils classification according to samples analyzed in the laboratory.

Table 2. Results of the laboratory (CBR) and Dynamic Cone Penetrometer tests CBR (Laboratory) Depth DCP Samples Date (%) (cm) (mm / blow) 0,1" 0,2" Maximum 1 14/04/12 22,0 - 34,0 60,0 2,8 3,2 3,2 2 19/04/12 26,0 - 39,5 22,5 8,6 8,3 8,6 3 19/04/12 37,0 - 60,5 78,0 3,4 3,0 3,4 4 19/04/12 23,5 - 39,5 32,4 7,6 7,0 7,6 5 03/05/12 35,5 - 51,0 30,7 5,9 5,2 5,9 6 03/05/12 52,0 - 74,5 74,0 3,4 3,4 3,4 8 10/05/12 26,5 - 48,0 72,0 2,8 2,8 2,8 10 12/05/12 42,5 - 66,5 120,0 2,3 1,9 2,3 11 24/05/12 41,0 - 59,5 61,5 3,4 3,4 3,4 12 24/05/12 42,0 - 55,0 43,0 4,2 5,1 5,1 13 26/05/12 58,0 - 73,5 51,5 4,3 4,8 4,8 14 26/05/12 24,0 - 37,5 34 6,1 6,0 6,1 15 09/06/12 45,0 - 66,5 107,5 2,7 2,6 2,7 16 09/06/12 41,0 - 58,0 55,0 4,8 4,0 4,8 17 09/06/12 57,0 - 72,5 51,5 6,3 5,0 6,3 19 10/08/12 40,5 - 53,0 62,5 5,2 4,1 5,2 20 10/08/12 38,0 - 55,5 58,0 4,3 3,8 4,3 22 13/08/12 34,0 - 48,5 72,5 3,4 2,8 3,4 24 15/08/12 40,5 - 55,0 48,5 5,3 4,5 5,3 26 16/08/12 33,0 - 51,0 45 4,5 4,1 4,5 27 16/08/12 38,0 - 59,5 72 3,6 3,1 3,6 28 16/08/12 34,0 - 48,0 34,5 5,2 4,9 5,2

2069 International Journal of Applied Engineering Research ISSN 0973-4562 Volume 13, Number 4 (2018) pp. 2068-2071 © Research India Publications. http://www.ripublication.com

29 17/08/12 26,5 - 46,5 49 5,3 4,3 5,3 31 22/08/12 31,5 - 45,3 27,3 7,9 7,0 7,9 32 22/08/12 38,0 - 55,0 56,5 4,1 3,4 4,1 33 22/08/12 32,5 - 45,5 33,5 6,3 6,0 6,3 34 24/08/12 48,0 - 63,5 51,8 5,6 4,4 5,6 35 24/08/12 21,5 - 38,0 55,5 4,1 3,6 4,1 36 28/08/12 29,0 - 43,5 36,5 5,9 5,0 5,9 38 28/08/12 24,5 - 42,5 90 3,4 2,9 3,4 39 29/08/12 31,5 - 44,5 43 6,6 5,5 6,6 40 29/08/12 23,5 - 45,5 73,5 3,5 2,7 3,5 41 01/10/12 22,0 - 37,5 38,5 4,8 4,4 4,8 42 01/10/12 30,0 - 46,0 32,9 7,6 7,0 7,6 43 02/10/12 19,5 - 34,0 48 4,9 3,7 4,9 44 02/10/12 34,0 - 50,0 53,5 5,4 4,4 5,4 45 05/10/12 15,0 - 28,0 32,50 9,9 8,00 9,9 46 05/10/12 16,0 - 34,5 45,5 6,2 4,9 6,2

12.0

10.0

8.0

6.0 CBR (%) CBR 4.0

2.0

0.0 0.0 20.0 40.0 60.0 80.0 100.0 120.0 140.0 DCP (mm / blow)

Figure 1: Dispersion diagram and correlation curve between maximum DCP and CBR

Figure 1 shows points dispersion and correlation curve between for indirect determination of CBR based on DCP Index, DCP and the maximum CBR. particularly, for fine subgrade soils from Sincelejo city in Colombia. The curve obtained in Figure 1 showed good adjustment, with a determination coefficient greater than 80%. This indicates that the correlation equation found has a good representation REFERENCES for the data obtained in the test [11]. Equivalent results were found by other authors [12] for Barranquilla city in Colombia, [1] Bowles, J., 1980, Bowles’s Manual, National located about 240 km, north of Sincelejo city. These were also University of Colombia, McGraw-Hill S.A., Bogotá, carried out on fine subgrade soils. The correlation equation Colombia, First edition. between DCP and CBR is shown below. [2] Montejo, A., 2006, Pavement Engineering, Catholic 112.03 University of Colombia, Bogotá, Colombia, Third 퐶퐵푅 = Equation 2. (퐷퐶푃)0.803 edition. [3] Crespo, C., 2002, Communication Roads, Roads,

Railroads, Airports, Bridges and Ports, Mexico D.F., CONCLUSIONS Editora Limusa S.A Grupo Noriega Editores, First Based on the results of this research study, the obtained edition. correlation equation can be considered as a reliable alternative [4] Wu, S., and Sargand S., 2007, Use of dynamic cone

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penetrometer in subgrade and base acceptance, Ohio University, USA. [5] Tupia, C., and Alva, J., 2001, Evaluation of the ground support capacity through a dynamic penetration team. XI Ibero-Latin American Asphalt Congress, Lima, Perú. Memoirs. [6] Thives, F., and Padilha, L., 2001, Contribution to the geotechnical research of paved urban roads through dynamic cone penetrometer test. MSc. Thesis, Federal University of Santa Catarina, Technological Center, San Carlos, Brazil. [7] American Standard Testing Materials, 2003, "Standard Test Method for Use of the Dynamic Cone Penetrometer in Shallow Pavement Applications," ASTMD-6951. [8] Márquez, J., and Robles, J., 2012, Determination of the correlation equation between the cone dynamic penetrometer (PDC) and the california support relationship (CBR) for the fine soils of the southern zone from the city of Sincelejo. Thesis, University of Sucre, Sincelejo, Colombia. [9] National Institute of Roads, INVIAS, 2007, Normal test method for the use of dynamic cone penetrometer in shallow-surfaced applications, I.N.V.E-172-07. [10] Instituto Nacional de Vías, INVIAS, 2007, Soil Support Relationship in the Laboratory, I.N.V.E-148- 07. [11] Spiegel, M., and Stephens, L., 2001, Schaum's Outline of Statistics, McGraw Hill Companies, Inc., Mexico D.F., Third Edition. [12] Castro, E., and Vives, Manuel, 1998, Correlations between the Dynamic Cone Penetrometer (PDC) and the California Support Relationship (CBR) for the fine soils of the southwestern zone of Barranquilla. Thesis, University of the North, Barranquilla, Colombia.

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