Physical and Geotechnical Properties of Tropical Peat and Its Stabilization

The chapter presents the physical and engineering properties of tropical peat treated with various types of stabilizers. Quick lime (QL), fly ash (FA), and ordinary Portland cement (OPC) were used as stabilizers. The amounts of QL, FA, and OPC added with the peat samples are in the range of 2–8, 5–20, and 5–20%, respectively. Various physical or index and engineering tests have been conducted to characterize the peat samples. Unconfined compressive strength (UCS) tests were conducted on original and treated peat samples cured for 7, 14, and 28 days. The results show that the UCS value increases with the increase of all stabilizers used and with curing period. The UCS tests were also conducted on the peat samples with the combination of QL and FA to study the combined effects of the stabilizers. The present study established different correlations between physical and engineering properties of original peat and UCS results on treated peat samples with different types of stabilizers. Geotechnical engineers can refer to these correlations to determine the bearing capacity of treated peat. In addition, scanning electron microscope (SEM) studies were conducted on original and treated peat samples to investigate the microstructure of the samples

Chemical Stabilization of Amorphous Peat Using Cement and Fly Ash at Different Water Additive Ratios

Peat is a very problematic soil as it is poor in strength. However, previous researchers have proven that the compressive strength of peat can be improved by using various methods of soil improvement including chemical stabilization method. In this study, cement and fly ash and lime were additives used and were mixed with amorphous peat at various water additive ratios. To replicate actual stabilization on site, water additive ratio is proposed as to allow stabilization to be performed at natural water content of the peat. Peat samples were collected from Kampung Endap, Samarahan and mixed at its natural moisture content with cement and with fly ash and lime at different water additive ratios of 3.0, 3.5, 4.0, 4.5 and 5.0. The compressive and bearing strengths of the samples were obtained by the unconfined compressive strength (UCS) test and California Bearing Ratio (CBR) test respectively. The results of the study have shown that there is marginal strength gained after 28 and 56 days of air curing period. The peat samples stabilized with cement at 3.5 water additive ratio recorded the highest value with UCS value of 69.48 kPa after 56 days of curing and 0.52 % for CBR test after 28 days curing period. These strength values obtained are lower compared to published data from previous studies. Different technique of mixing in the laboratory that is mixing peat at its natural water content with varied amount of additives at selected water additive ratio as opposed to mixing at maximum dry density and optimum moisture content that is mostly performed in laboratory contributes to the outcome. However, this study has proven that there is an increase in compressive and bearing strengths of stabilized peat in its natural water content compared to original peat without stabilizer

Laboratory measurement of displacement on shallow foundation in uniform sand using particle image velocimetry technique

Particle Image Velocimetry (PIV) is one of the non-intrusive techniques recently being utilized for measuring soil displacement in geotechnical engineering. The work discussed in this paper focuses on the application of an image processing tool known as MatPIV, a freeware readily available to the general users. The test programmes involved measurement and visualization of the behavior of displaced soil under various type of loadings and sizes of the foundation plate. Prior to testing, validation test was performed to study on the validity of measurements produced by MatPIV by comparing its measurements with the actual. Boundary analysis was also performed to justify on the configuration chosen for the model box used in both validation and experimental set-ups. In addition, a set of 70 displacement data was also studied in the validation test and a further statistical analysis on the data showed an acceptable accuracy of 98.8% for the MatPIV analysis when compared to the actual measured displacement. Hence, further test programmes which consisted of various soil-structure interaction conditions were performed. This comprehensive analysis showed that the diameter of loading rods and the sizes of foundation plate do affect the behavior of soil displacement under centric structural loading and was shown successfully via MatPI

Chemical Stabilization of Sarawak Clay Soil with Class F Fly Ash

Chemical stabilization of Sarawak clay soil was studied via Fly Ash (FA) due to their potential benefit. FA is a by-product produced from thermal power plant and disposal of FA causing an environmental hazard. Investigation on the feasibility of FA as a potential stabilizer to stabilize the Sarawak clay soils was performed via Unconfined Compression Strength (UCS) and Triaxial Consolidated Isotropic Undrained (CIU). From the compaction results, the Maximum Dry Density (MDD) and the Optimum Moisture Content (OMC) for all mixtures increased and decreased respectively compared to natural soil. Based on the UCS test, the addition of 20% FA and 40% FA achieved a significant improvement in compressive strength and recommended as optimum stabilizer amount. The plasticity index and linear shrinkage for the FA stabilized soil decreased compared to the natural soil. The triaxial test was performed for the optimum amount of stabilizer and obtained significant improvement in effective cohesion and effective internal friction angle compared to natural soil. The deviator stress for FA stabilized soil also increased compared to the natural soil corresponding to the confining pressure. The morphology of stabilized soil shows the existence of cementitious product, which contributed to strength increased as observed via Scanning Electron Microscopy (SEM)

A Review on the Behaviour of Combined Stone Columns and Pile Foundations in Soft Soils when Placed under Rigid Raft Foundation

In the last few decades, it has been observed that raft foundations are very commonly used as a foundation solution for moderate to high rise structures either by resting on stone columns or on piles in soft soils. It is believed that, combining stone columns and piles in one foundation system is the more suitable foundation for medium rise structures. The combined foundation system provides a superior and more economical alternative to pile, and a more attractive alternative to stone columns in respect to ground improvement. This paper presents the review of existing studies reported in the literature in the last two decades about the behaviour of stone columns under raft foundations and piled raft foundation in soft soil, notably the failure mechanism and the bearing capacity. Also, a limited work from the literature concerning the performance of combined (pile/stone columns) foundation system in soft soil is comprised. Furthermore, very extensive ongoing research work regarding the investigation and study on the performance of combined (pile/stone columns) foundation system in soft soils is discussed. The main goals and methodology to study the performance of the combined (pile/stone columns) foundation systems in soft soil are also addressed

Importance of sustainable polymers for modern society and development

Polymers are one of the most important and enormously used materials in the modern society. Scientists and researchers keep on improving this material via their studies and research, in order to come up with sustainable properties with the finest products. In this study the significance of sustainable polymers for modern society and development had been expanded. In addition, the current applications of synthetic and biodegradable polymers and its positive and negative impacts on the environment are also stated. The polymeric materials waste management and the sustainability of biodegradable polymers are specified

Correlation of Different Peat Soil Index Properties

The present study focuses on the physical properties of Sarawak peat soil and identifies the correlation between the index properties of peat from the present study and various locations in Malaysia. The physical properties of peat from the present study were obtained on site and in the laboratory, including degree of humification, moisture content, organic content, fibre content, specific gravity, liquid limit, linear shrinkage, and pH. The data obtained in this study and other tropical peats in Malaysia were compiled to identify their correlations. The correlation results reveal that with an increase in organic content, there is also an increase in value of moisture content, while the value of specific gravity reduces. Furthermore, as the bulk density of peat increases, the value of organic content reduces. Also, the moisture content, organic content, and fibre content of peat decrease with the increasing value of degree of humification. The correlations between different peat soil index properties have R2 values ranging from 0.75 to 0.85, showing that the peat soil index properties are consistent with findings from previous studies, in which comparable trends are found. Thus, these correlations are expected to be useful for researchers and engineers to understand the peat soil's preliminary behaviour

A laboratory miniature full-flow penetrometer system for peat

Uncertainties and difficulties surrounding laboratory strength testing of peat have caused the increasing reliance on in situ testing methods, which include T-bar and ball penetrometers, to determine the undrained strength of peat for design purposes. This paper presents the results of miniature full-flow penetrometer (T-bar and ball) tests on decomposed peat samples to provide a better understanding of the interpretation of the strength parameters in this material. The tests were conducted in a pressure chamber, in which miniature T-bar and ball penetrometer tests can be performed on peat samples consolidated under specific vertical effective stresses. Penetrometer bearing factors were derived experimentally using the monotonic penetration resistance and the undrained shear strength estimated from triaxial tests. The bearing factors, expressed as the penetration resistances normalised by the undrained shear strength data (obtained from triaxial tests) compare well with those derived from plasticity solutions. In addition, the remoulded strength parameters derived from penetrometer cyclic tests are comparable with those obtained from fall cone tests. The findings reported in this paper illustrate the capability of full-flow penetrometer tests to measure the undrained strength of peat

Correlation of Different Peat Soil Index Properties

The present study focuses on the physical properties of Sarawak peat soil and identifies the correlation between the index properties of peat from the present study and various locations in Malaysia. The physical properties of peat from the present study were obtained on site and in the laboratory, including degree of humification, moisture content, organic content, fibre content, specific gravity, liquid limit, linear shrinkage, and pH. The data obtained in this study and other tropical peats in Malaysia were compiled to identify their correlations. The correlation results reveal that with an increase in organic content, there is also an increase in value of moisture content, while the value of specific gravity reduces. Furthermore, as the bulk density of peat increases, the value of organic content reduces. Also, the moisture content, organic content, and fibre content of peat decrease with the increasing value of degree of humification. The correlations between different peat soil index properties have R2 values ranging from 0.75 to 0.85, showing that the peat soil index properties are consistent with findings from previous studies, in which comparable trends are found. Thus, these correlations are expected to be useful for researchers and engineers to understand the peat soil's preliminary behaviour

Variable penetration rate testing for shear strength of peat – a review

This paper presents a review of the advances in the variable penetration rate testing methods on inorganic soils and its potentials to investigate the appropriate penetration rate and resistance factors for penetrometer testing of peat. A partially drained condition, which often leads to misinterpretation of test results, has been observed in peat penetration testing when the standard rate of 20 mm/s is used. Although the impact of rate-effects on penetration resistance measured with CPTu, T-bar and ball penetrometer have been investigated extensively in various intermediate soils, research is limited on how penetration rate controls drainage conditions and affects consolidation behaviour in peat. This review synthesises research developments in using variable penetration rate tests. The objective is to evaluate the transition of drainage conditions and consolidation behaviour of inorganic soils while focusing on its adaptability for peat. The review provides guidance on the investigation of the penetration rate testing in pea