Thermal Imaging Study on The Effect of Permeability on Smouldering Behaviour of a Tropical Peat

Smouldering is a slow-burning, low-temperature, flameless combustion, and frequently happens in peatland fires. The smouldering spread occurs because of the parameter achievement in oxygen supply, generated heat, and heat released to the environment. The condition of porous and fibrous peat soils makes oxygen supply easily happens. The difficulty of getting to the location of the burning peatland is one of the problems to extinguish the fire. This study aims to observe with thermal imaging study the effect of peat permeability on smouldering behaviour of a tropical peat sample. Mechanical compaction was applied to reduce permeability and pore value in the central of the peat soil. Then, peat soil is ignited to create the smouldering propagation through the compacted peat area. The combustion process that occurs on the surface is observed by a visual camera and an Infrared FLIR Thermal Camera. The initial results showed a reduction in the smouldering spread rate on the compacted soil region as compared to the undisturbed peat smouldering region. Nevertheless, smouldering combustion of peat still occurred in all regions of the reactor, once the smouldering front could penetrate the compacted region.

Cyclic Shearing Behavior and Dynamic Characteristics of a Fibrous Peat

Cyclic shearing behavior, dynamic characteristics, and post-cyclic volume change of a peat sublayer from the Port Lands area of Toronto (Ontario, Canada) are investigated in this study. Laboratory specimens are trimmed from block samples collected from a depth of about 4.0 to 4.5 m. Constant-volume cyclic direct simple shear tests indicate an initial reduction of effective stress with number of stress cycles. However, the corresponding excess pore pressure ratios do not exceed 60%, indicating a cyclic mobility behavior in the peat specimens. Maximum shear moduli of the peat samples are also determined from shear wave velocity measurements. Post-cyclic volumetric strain, as well as the variations of secant modulus, modulus reduction, and damping ratio of the peat are presented in terms of cyclic shear strain and compared with other studies. Empirical relationships are proposed for characterizing the shear modulus and damping ratio of Toronto peat.

Shrinkage Behavior of Peat – Polymer Mixtures

Peat soil is a challenging soil with brownish-black in color, consist of high decomposed organic material, high moisture content (>100%), high compressibility (0.9-1.5), low shear strength (5-20 kPa) and high organic matter (>75%). Peat with high moisture experienced it’s highest decreased of moisture when dried. With the larger shrinkage capacity, the fibrous peat are able to reduce the volume up to 50% following air drying. The objective of this study is to identify the shrinkage behavior of original peat and stabilized peat by using Vinyl Acetate – Acrylic Copolymer (VAAC). In this study, a laboratory investigation was conducted by using bar linear shrinkage and cylindrical sample measurement. This polymer can be used to increase the strength of soil and also able to fill the pore medium thus create water proof surface upon drying. Hence the moisture loss can be control and the shrinkage can be reduced. Results show that the value of original peat shrinkage is 26.17% and 28% for bar linear shrinkage method and cylindrical sample measurement method respectively. After added VAAC mixtures, the shrinkage reduce up to 9% and 12% for both method. Hence, this VAAC polymer can be concluded as a good agent to control the shrinkage problems.

Characteristics of Palangkaraya fibrous peat

Palangkaraya fibrous peat soil is a soil with high organic content and was formed due to decomposition of plants in submerged areas for long periods. In the tropics, peat has a high fiber content that affects the physical and engineering characteristic and have different behavior with clay. Laboratory and field tests were conducted to determine the physical and engineering characteristic of fibrous peat and to compare it with clay. The results of the tests on fibrous peat show peat soil parameter very different from clays. The unit weight of peat is 1.04 gr/cm3 with specific gravity is 1.4 and water content reach 650%. This physical parameter shows that peat is a very soft soil that is dominated by water in its structure. Organic content of peat reached 97% with a very low ash content of 3%. This behavior indicates that the decomposition of plants causes physical properties of peat that are very different from clays. The bearing capacity of the peat is also very low. The shear strength was about 26.8 kPa (ov = 50 kPa) and was dependent on the fiber distribution in the sample under test. Vane shear test results also show the same thing that is 5-7 kPa. The very different behavior of fibrous peat with clay is the consolidation. Peat has 4 stages of compression wherein secondary compression is the main compression. This behavior is due to the fibrous peat has two pores, that are micropores and macropores. The results of comparisons can serve as a basis for determining appropriate peat soil improvement methods.