Effect of Sand Compaction Piles on the Swelling and Shrinkage Behavior of Expansive Soil

This study aims to investigate the effect of sand compaction piles on the swelling and shrinkage behavior of expansive clay soil. A series of experimental laboratory tests were carried out using the modified Proctor mold and a circular footing. The diameter of the sand compaction pile was selected to give a replacement area ratio equal to 57%. To model the swelling and shrinkage cycles, water was added to the sample and the heave was recorded at regular time intervals. The shrinkage was obtained by heating the outer surface of the modified Proctor mold at a temperature of 110°C ± 5°C by a development heating system designed for this purpose to accelerate the shrinkage process. The vertical movement was recorded at regular time intervals. The swelling and shrinkage cycles were carried out under an externally applied pressure equal to 120 kPa. The main results of this study showed that, for untreated expansive soil, the swelling potential reaches the highest value at the second cycle and started to decrease for the subsequent cycles. After the fourth cycle, the swelling potential decreases and reaches about half the value of the initial swelling potential and the equilibrium state occurs. For expansive soil treated with a sand compaction pile, it is found that there is a significant reduction in both swelling and shrinkage potential. Moreover, it is observed that after the first cycle both the swelling and shrinkage potential decrease significantly, and both reach a negligible value after the second cycle.

PENGUJIAN TANAH EKSPANSIF DENGAN SKALA MODEL MENGGUNAKAN KAYU DOWEL SEBAGAI PENGGANTI DINDING PENAHAN TANAH

Foundation is one of the most important thing in a construction. The frequently used foundation in construction is pile foundation. In Indonesia the used of pile is adapt by the condition and quality of the soil. Indonesia had many types of soil, and one of them is expansive soil. Expansive soil is a type of clay that had a swelling and shrinkage potential where the swelling happen when the water content is increase and shrink when the water content decreased. One of the mineral that can cause swelling is montmorillonite mineral in expansive soil. The chemical chain between particles that influenced by the increase of water content is causing montmorillonite mineral to swell. The focus of this research is lateral movement that happened to pile as an effect of the swelling properties in expansive soil. This analysis will also inform the effectiveness on using different size and number of pile in expansive soil. Fondasi merupakan salah satu bagian terpenting dalam suatu konstruksi. Salah satunya yang sering digunakan pada proses pelaksanaan konstruksi adalah fondasi tiang pancang. Di Indonesia sendiri penggunaan fondasi tiang pancang disesuaikan dengan kondisi dan kualitas dari tanah yang ada. Indonesia memiliki berbagai macam tipe dan jenis tanah yang berbeda, salah satunya adalah tanah ekspansif. Tanah ekspansif merupakan jenis lempung yang memiliki daya pengembangan dan penyusutan dimana pengembangan tersebut terjadi jika adanya penambahan kadar air dan menyusut ketika terjadi pengurangan kadar air. Salah satu yang dapat menjadi penyebab terjadinya pengembangan adalah kandungan mineral montmorillonite yang terdapat pada tanah ekspansif. Ikatan kimia antar partikel yang dipengaruhi oleh adanya peningkatan kadar air tanah menyebabkan mineral montmorillonite pada tanah ekspansif tersebut akan mengembang. Analisis yang dilakukan akan berfokus pada pergeseran lateral yang terjadi pada tiang pancang sebagai akibat dari dampak pengembangan yang terjadi pada tanah ekspansif. Analisis ini juga menghasilkan efektivitas pada penggunaan ukuran dan jumlah tiang pancang ditanah ekspansif.

Indexes of residual shrinkage to quantify the comparative effects of zero and mechanical tillage on a vertisol

Differences in the soil physical condition of the surface layer of a Vertisol (near Warwick, Queensland) under a zero versus mechanical tillage trial were investigated by using indices derived from a limited part of the soil's shrinkage curve. Shrinkage data were generated by coating initially air-dry clods in SARAN resin, then oven-drying them in six temperature increments to 105�C. Values of both the slope and y-axis intercept of a straight-line fit to the data were significantly greater in the mechanically tilled treatment. This showed that mechanical tillage led to decreased bulk density (increased porosity) and caused the soil to have greater shrinkage potential.