## 1 Introduction  
The standard test method designated as ASTM D6951/D6951M-09 [1] (entitled the Standard Test Method for Use of the Dynamic Cone Penetrometer in Shallow Pavement Applications) is initiated to assess pavements for strength evaluation. It is claimed that the penetration rate may be related to the in situ strength, such as the California bearing ratio (CBR) and the soil density when the type of soil and water content are known. The test is carried out with an 8 kg hammer and the option of a 4.6 kg hammer to suit fine-grained soils or when excessive penetration is expected with heavy hammers. A schematic diagram of the DCP device is presented in Figure 1.  
This tool can be utilized in the assessment and control of clay-sand mixture layers used in liners and the waste disposal process. It is handy, quick, and more reliable when used in homogenous soil. The compacted clay liners are generally assumed to have a uniform moisture content and be free from gravel and boulders. This dynamic penetration test is ideal for assessing the shear strength and dry density of such layers. The heavy version (8 kg hammer) may not be needed and only the lightweight hammers can be utilized. Clay-sand liners often include bentonite as a clay additive, which is known for its high expansion. The field density tests normally conducted at the time of construction can be subjected to serious changes due to the swelling nature of the material. The expansion will cause the density and shear strength to drop significantly when wetting occurs as a result of possible changes in the environmental conditions [2]. The clay used in liners and water barriers is commonly highly plastic or processed commercial bentonite. The cost of processed clay and bentonite has led many researchers to investigate the use of local materials. [PERSON] et al. (2005) investigated the use of Oman shale in liners [3]. Reference [4] [PERSON] et al. (2009) investigated the use of Auchi shale and Imo shale in waste disposal landfills in Nigeria. [PERSON] et al. (2008) [5] studied the permeability of clay liners of some geological formations and different depositional basins in Turkey. These are only some examples, and the research is continuous. Compacted clay-sand mixtures have frequently been introduced to act as barriers in waste disposal and containment. The failure of a landfill liner can occur when the hydraulic conductivity is increased beyond a specified limit or when a failure occurs as a result of a chemical attack or cracks developing within the clay-sand mixture. General specifications of soil liners can vary from one project to another. Some tolerance for an amount of water to be allowed to pass can be considered. [PERSON] (1993) [6] suggested that the coefficient of hydraulic conductivity for liner materials is \(\leq\)10\({}^{-7}\). (cm/s). [PERSON] [7] demonstrated the successful use of natural clays with moderate to high plasticity in Saudi Arabia. The cone penetration concept is used in determining the liquid limit for clays and has been standardized for a long time in practice (BS 1377, ISO 17892-6) [8,9] often called  
Figure 1: Schematic diagram of Dynamic Cone Penetrometer device (ASTM D5951/D5951M-18). the fall cone test procedure. The definition of the liquid limit is the moisture content at which a clay material starts to behave like a liquid. This occurs at very low shear strength. The fall cone can be designed to measure the shear strength (\(S_{u}\)) in kPa using the Hansbo formula [10]:  
\[S_{u}=k(\frac{m\times g}{d^{2}}) \tag{1}\]  
where  
\(Su=\) shear strength;  
\(k=\) a cone coefficient;  
\(m=\) mass of the cone;  
\(g=\) acceleration of gravity;  
\(d=\) the cone penetration measured in mm. The mass of a 30\({}^{\circ}\) cone is 80 g, and k is the cone coefficient, which was taken as 0.8 for the cone size and geometry for the fall cone used in the laboratory to determine the liquid limit. \(g\) is the acceleration of gravity (m/s\({}^{2}\)), and d is the cone penetration depth measured in mm.