## 5 Discussion  
### Dynamic Cone Penetrometer  
The dynamic cone penetrometer profiles obtained for two layers with different bentonite content (5% and 10%) indicate variations in three different measurements. These include the linearity, slope, and magnitude. In Figure 4, presenting the bottom row results, we can clearly observe that the material compacted at the optimum moisture content had a linear trend. This was validated in both the 5% and 10% bentonite content. The shape observed for the dry of optimum results indicates a bilinear trend in which a greater number of blows (beyond five) was required to advance the DCP for the 5% clay content. Further advancement of the cone was resisted by a pocket of sand grains closely packed after applying five blows of the hammer. A bilinear shape did not develop for the compacted  
Figure 14: Horizontal displacement vs. vertical displacement for mixture with 10% bentonite under OMC condition.  
Figure 13: Horizontal displacement vs. shear stress for mixture with 10% bentonite under OMC condition.  
material including 10% bentonite for the dry of optimum moisture content and the other two states of moisture.  
The slope of penetration for the optimum moisture mix was intermediate between the dry of optimum and wet of optimum compacted layers of 5% bentonite content while it was flatter and less steep than the dry of optimum and wet of optimum conditions in the 10% bentonite mixture.  
The number of blows required to advance the cone penetrometer 5 cm into the 5% bentonite mixture was in the range of 4 to 7 blows for the mixture compacted at optimum moisture conditions. For the dry of optimum and wet of optimum conditions, the ranges of blows were from 2 to 4 blows and from 7 to 10 blows, respectively. For the 10% bentonite mixture, the number of blows required to advance the cone penetrometer for 5 cm was in the range of 10 to 12 blows under the optimum moisture conditions. For the dry of optimum and wet of optimum conditions, the ranges of blows were from 7 to 8 blows and from 5 to 6 blows, respectively.  
In Figure 5, which presents the central row, the results appear to be similar to those presented in Figure 4, except for an outlier point (at or >10 blows) observed for the 5% bentonite that deviated from the linear optimum state line.  
Figure 6 presents the top row points. The results appear to be similar to those presented in Figure 4 except for a point of deviation from linearity (at or >10 blows) observed for the 5% bentonite. In addition, the slope of the optimum state is not necessarily flatter than the other moisture states in the 10% bentonite mixture layer.  
Based on the above observations, we can see that the comparison between the DCP points data is useful and valid and had good accuracy when the material was homogeneous. When the clay content and the grain size distribution were different, the linearity and the shape and magnitude of penetration were variable. To rely on the DCP data, it is recommended to conduct grain size distribution tests to confirm the uniformity of the site material and to enable adjustments if necessary.  
The state of moisture during compaction influences the outcome of the DCP with regard to the shape, slope, and number of blows. It is recommended to avoid compaction under a wet of optimum state.  
Compactness and density also influence the number of blows. Stress portioning is a state in which clay supports part of the cone pressure and coarse grains support the other part. A high clay content may reduce stresses exerted on the coarse grains, and then a lower number of blows will be reported.