Determination of Unconfined Compressive Strength and Atterberg Limit of Soft Clay by Stabilizing with Sodium Silicate and Biomass Silica in Batu Pahat

Soft clay soils can be considered as problematic soil with the characteristic of high compressibility, low permeability and low shear strength. Construction on soft clay deposit may causes problem such as insufficient bearing capacity, settlement problem and instability on excavation and embankment. Ground improvement methods were used as the aimed of this study is to determine the effect of non-traditional stabilizer on the compressive strength of soft clay soils. Therefore, the objective of this study is to determine effect of compressive strength of untreated and treated soft clay soil with addition of non-traditional stabilizer at different curing periods. The soil properties of soft clay soil such as compaction, Atterberg limits, and unconfined compression strength (UCS) testing methods were used to observe the performance of treated and untreated samples. The test results from the UCS indicated that once Biomass Silica and Sodium Silicate in the form of SH-85 and TX-85 have been added to the clay soil, the strength of the sample will increase with increasing percent of sodium silicate and curing periods.

The Implementation of Industrial Byproduct in Malaysian Peat Improvement: A Sustainable Soil Stabilization Approach

Peat is a well-known problematic soil associated with poor engineering properties. Its replacement with an expensive competent foundation material is practiced for road embankment construction which is costly and causes greenhouse gas emissions. Therefore, this paper investigated the effectiveness of a byproduct from a metal industry (silica fume) to stabilize peat along with ordinary Portland cement (OPC) through a series of experimental tests. After peat-indexed characterization, a number of standard compaction and mechanical tests were performed on the stabilized and parent peat. For this purpose, nine designated mixes were prepared possessing various combinations of silica fume (SF) and 10–20% OPC. Unconfined compressive strength (UCS) and California Bearing Ratio (CBR) tests were carried out after 7, 14, and 28 days of curing to assess strength enhancement and binder effectiveness, and the microstructural evolution induced by the binders was examined with scanning electron microscopy (SEM). The analysis revealed a substantial improvement in mechanical properties with the incorporation of SF and OPC, ultimately meeting the minimum strength requirement for highway construction (i.e., 345 kPa). A peak UCS of 1063.94 kPa was recorded at 20% SF, and an unsoaked CBR value of 42.95 was observed using 15% SF and 15% OPC after 28 days of curing. Furthermore, the increasing percentage of hydraulic binders exhibited brittle, collapsible failure, while the microstructural study revealed the formation of a dense matrix with a refined pore structure in the treated peat. Finally, a significant statistical analysis was carried out by correlating the test parameters. In this way, rather than stockpiling and dumping, an industrial byproduct was implemented in peat stabilization in an eco-friendly manner.

Effect of wood vinegar and rice husk biochar on soil properties and growth performances of immature kenaf (Hibiscus cannabinus) planted on BRIS soil

Beach ridges interspersed with swales (BRIS) soil is identified as one of Malaysia's problematic soil since this type of soil contains a plethora portion of sand texture that contributes to water and nutrient leaching causes infertile soil. A polybag trial was conducted to evaluate the effects of wood vinegar and rice husk biochar on soil properties and growth performances of immature kenaf. The plant was arranged in a completely randomised design with four treatments and three replications. The factors taken for the experiment were four different media compositions, i.e., T1(control), T2(BRIS soil amended with wood vinegar, WV), T3(BRIS soil amended with rice husk biochar, RHB) and T4(BRIS soil amended with wood vinegar and rice husk biochar, WV+RHB). Rice husk biochar and a combination of wood vinegar with rice husk biochar significantly improved soil properties in terms of soil moisture content, organic matter, water retention and soil porosity, as well as significantly increased the kenaf stem diameter. However, there was no significant difference in plant height, number of leaves, leaves area and chlorophyll content on different treatments medium. In conclusion, the application of rice husk biochar and wood vinegar in this study enhanced BRIS soil properties and showed a positive effect on the growth of immature kenaf.

Assessment of Physical and Mechanical Properties of Polyurethane as Ground Improvement Material for Peat

Peat is considered problematic soil due to its large void ratio, high compressibility and low shear strength. Various ground improvement methods have been developed in recent years to improve peat’s strength properties. Polyurethane grouting is one of the ground improvement methods that is gaining recognition as effective and fast way to stabilize soil. Polyurethane is a lightweight material produced by mixing polyol and isocyanate chemicals. Upon mixing, a polyurethane foam is created which expands up to a few times of its original volume. In this study, the strength characteristics of polyurethane with different mix ratios of polyol to isocyanate were evaluated to determine the optimum ratio suitable to be used to stabilize peat. Polyol to isocyanate ratio of 1:1, 1:1.5, 1:1.2, 1:2.5 and 1:3 were tested in this this research. The propagation, microstructure and density of polyurethane were investigated. Compressive strength of polyurethane determined using Unconfined Compression Strength test. Polyurethane created with higher ratio of isocyanate bears higher density and compressive strength compared to the polyurethane with lesser quantity of isocyanate. The cell structure of the polyurethane also is smaller with thicker cell walls. However, the curing time consumed by the polyurethane with high ratio of isocyanate is 8 times greater than the normal polyurethane. Thus, polyurethane ratio with fast curing time and high compressive strength was chosen as the optimum mix ratio to be used to stabilize peat.

Effectiveness of strip footing with geogrid reinforcement for different types of soils in Mosul, Iraq

The main cause of problematic soil failure under a certain load is due to low bearing capacity and excessive settlement. With a growing interest in employing shallow foundation to support heavy structures, it is important to study the soil improvement techniques. The technique of using geosynthetic reinforcement is commonly applied over the last few decades. This paper aims to determine the effect of using geogrid Tensar BX1500 on the bearing capacity and settlement of strip footing for different types of soils, namely Al-Hamedat, Ba’shiqah, and Al-Rashidia in Mosul, Iraq. The analysis of reinforced and unreinforced soil foundations was conducted numerically and analytically. A series of conditions were tested by varying the number (N) and the width (b) of the geogrid layers. The results showed that the geogrid could improve the footing’s bearing capacity and reduce settlement. The soil of the Al-Rashidia site was sandy and indicated better improvement than the other two sites’ soils (clayey soils). The optimum geogrid width (b) was five times the footing width (B), while no optimum geogrid number (N) was obtained. Finally, the numerical results of the ultimate bearing capacity were compared with the analytical results, and the comparison showed good agreement between both the analyses and the optimum range published in the literature. The significant findings reveal that the geogrid reinforcement may induce improvement to the soil foundation, however, not directly subject to the width and number of the geogrid alone. The varying soil properties and footing size also contribute to both BCR and SRR values supported by the improvement factor calculations. Hence, the output complemented the benefit of applying reinforced soil foundations effectively.

Stabilization of Clayey Soils by Using the Organic Waste-Material

Soil stabilization known as the process of improving the engineering properties of soils is a method applied when the engineering properties of soil are not suitable for purpose. There are several methods of soil stabilization that could be implemented to improve the physical characteristics of the soil. In this study, the pine tree sawdust as an organic material wase used as additive material for stabilization of clayey soils and the influence of pine tree sawdust on the geotechnical properties of clayey soil was investigated in terms of strength behaviors. The pine tree sawdust is an organic waste resulting from the mechanical milling or processing of timber (wood) into various standard shapes and useable sizes. The strength properties of the clayey soil when blended with pine tree sawdust indicates that the pine tree sawdust is a good stabilization material for this problematic soil. As a result, it is concluded that the pine tree sawdust material as an organic material can be successfully used for the reinforce of clayey soils in the geotechnical applications.

CASE-BASED REASONING PEMILIHAN METODE KONSTRUKSI JALAN DI ATAS TANAH BERMASALAH KEDALAMAN 10 SAMPAI DENGAN 20 METER

Permasalahan konstruksi jalan di atas tanah bermasalah (problematic soil) tanpa adanya perbaikan tanah (soil improvement) maupun perkuatan tanah (soil reinforcement), pada umumnya akan mengakibatkan instabilitas timbunan dan penurunan tanah dasar. Tidak sedikit jaringan jalan di atas tanah dasar bermasalah di beberapa area di Indonesia mengalami penurunan tingkat pelayanan yang drastis sebelum umur rencana. Kurangnya pemahaman karakteristik tanah dasar menyebabkan pemilihan metode konstruksi tidak efektif dan efisien. Kecenderungan pemilihan metode yang digunakan masih didasari ketersediaan pagu anggaran. Pemilihan metode konstruksi jalan di atas tanah dasar bermasalah dengan analisis Case-Based Reasoning (CBR), dapat menghemat waktu dalam pengambilan keputusan berdasarkan keahlian pakar, sehingga risiko ketidakakuratan pemilihan metode berakibat pada keputusan penanganan yang kurang tepat dapat diminimalisir. Berdasarkan hasil analisis dengan mengambil studi kasus tol Pemalang – Batang pada kedalaman tanah bermasalah antara 10 sampai dengan 20 meter dan menggunakan analisis CBR, didapatkan gejala kecocokan (similarity) sebesar 97,74% pada metode Prefabricated Vertical Drain (PVD) yang dikombinasikan dengan metode pembebanan dengan vakum (vacuum preloading) dan Prefabricated Horizontal Drain (PHD).