Analysis of Unconfined Compressive Strength in Clay Mixed with Sand

Clay soils are soils that have high shrinkage potential and have good carrying capacity in water unsaturated conditions but poor in water-saturated conditions. Clay soil has a low carrying capacity, so to increase the carrying capacity of the soil it needs to be stabilized by using an added material which is sand. Land used for 100% disturbed soil, 95% disturbed soil + 5% sand, 90% disturbed soil + 10% sand, 85% disturbed soil + 15% sand, with curing time 3,7,14, and 28 days. The mixture was tested using aunconfined compressive strength test instrument with SNI 03-6887-2002 method. The results of the unconfined compressive strength test showed that the increase in maximum soil strength occurred in the addition of 90% disturbed soil + 10% sand at the age of 28 days curing, which reached 1,194 kg/cm2. But the results of unconfined compressive strength increased when the mixture of 85% disturbed soil + 15% of sand reaching 1,348 kg / cm2. Based on testing that the more amount of sand is added, the higher the value of unconfined compressive strength obtained.


Introduction
Asmat Regency is located in Papua with an area of 31,983.69 km² or 31.98% of the total area of Papua Province and is a division of Merauke Regency, the type of soil found in Asmat Regency consists of clay soil which is usually found in swampy areas and in lowland. In general, development in Asmat Regency is carried out on swamps and lowlands so that clay soil is a problem that must be overcome.
Clay soils have the property of expanding and developing several factors such as lithological variability at various scales, and cycles that vary repeatedly, on the behavior of clay [1] and have low bearing capacity. The compressive strength test of clay needs to be carried out to determine the compressive strength capacity of clay to be carried out with sand. Therefore, scientific and systematic research is needed to determine the character and proportion of each ingredient. In this study, the clay and sand materials used are local materials from several areas in Asmat Regency.

Location of Sampling
Obtaining the physical properties and mechanical properties of the soil that are limited in the UCS test was * Corresponding author: budiyanto_ft@unmus.ac.id carried out at the Civil Engineering Laboratory, Musamus University, Merauke.

Research Materials
 Soil samples taken and used in this study were sourced from Akantapak Village, Aswi District, Asmat Regency.  Sand samples taken and used in this study were sourced from Bawos Village, Aswi District, Asmat Regency.

Method of testing
 Testing of soil density is adjusted to SNI. [2] The tools used are hot plates, picnometers, ovens, electric scales, spatulas.  Testing of water content is adjusted to SNI. [3] The tools used are ovens, cups, electric scales.  Testing of grain analysis is adjusted to SNI. [4] The tools used are sieve filters, brushes, electric scales, water hoses, cups.  Atterberg boundary testing devices are adjusted to SNI. [4,5] est equipment used is casagrande, cup, glass with dimensions of 0.9 cm x 45 cm x 45 cm, spatula, oven.  Compaction test equipment adjusted to SNI. [6] The tools used are ovens, standard hammer proctors, standard proctors, electric scales, jacks.

Soil Properties
Based on the results of testing the physical characteristics of the soil in the laboratory, the following data were obtained:

Sand Properties
Based on the results of testing the physical characteristics of sand carried out in the laboratory, the following data were obtained:   Table 4.  2. Graph of the relationship between curing and the value of qu in the 95% soil + 5% sand test  Fig.3. Graph of the relationship between curing and the value of qu in the test of 90% soil and 10% sand Based on the results of the test data obtained and the graphic image shows the compressive strength of disturbed soil with a mixture of 90% soil and 10% sand at the age of 3 days is 0.608 kg/cm², while at the age of 28 days there is an increase of 1.194 kg/cm². The results of the undisturbed compressive strength test with a mixture of 85% soil and 15% sand can be seen in Table 6.  Fig.4. Graph of the relationship between curing and the value of qu in the test of 85% soil and 15% sand Based on the results of the test data obtained and the graphic image shows the compressive strength of disturbed soil with a mixture of 85% soil and 15% sand at the age of 3 days is 0.709 kg/cm², while at the age of 28 days there is an increase of 1.348 kg/cm². Based on the results of calculations on the UCS test for a mixture of soil and sandit can be concluded that the more addition of sand and the longer the curing age the higher the value of qu is shown in Figure 5.

Conclusion
Based on the results of the research and discussion above, it can be concluded that the maximum unconfined compressive strength test results occurred at 28 days of curing as follows: a. Score The unconfined compressive strength of the clay subgrade in Akantapak village is 0.924 kg/cm². b. Influence clay soil with mixer local sand against unconfined compressive strength.
• 95% land disturbed + 5% sand obtained the value of qu = 1.078 kg/cm². • 90% land disturbed + 10% sand obtained the value of qu = 1.194 kg/cm². • 85% Disturbed soil + 15% sand obtained the value of qu = 1.348 kg/cm². Judging from the test results above, it can be seen that the optimum qu occurs in the variation of the mixture of 90% disturbed soil + 10% sand of 1,194 kg/cm², and the effect of the addition of a mixture of sand can increase the strength of the soil, it can be seen in the test results above, where at the time of testing the sample of 85% disturbed soil + 15% sand obtained a qu value of 1.348 kg/cm.