Enhancing the bearing capacity of rigid footing using limited life kenaf geotextile reinforcement

This research focuses on soft clay improvement by using Kenaf textile as a natural geotextile reinforcement. A series of small-scale laboratory tests were conducted to study the impact of the geotextile reinforcement depth, d, the vertical spacing between reinforcement, S and the number of reinfor- cement layers, N on the bearing capacity of the soil model. The test results were verified using the numerical simulation by PLAXIS 2D. In this study, the influence factors included four different d/B ratios of 0.25, 0.5, 0.75 and 1.0; three different S/B ratios of 0.25, 0.5 and 0.75, and a different number of reinforcement layers, N from 1 to 4 were investigated where B is the footing width. The results clearly showed that the bearing capacity of rigid footings was significantly improved with the Kenaf geotextile layers in the kaolin. The measured and predicted bearing capacity results were in good agreement. The optimum d/B ratio and S/B ratio, which resulted in the maximum ultimate bearing capacity of the Kenaf-reinforced model ground were about 0.25 and 0.25, respectively. The optimum N was 3, i.e., the bearing capacity insignificantly improved even with N > 3

Estimation of wall friction of chamber box using consolidation characteristic

An estimation of wall friction during the consolidation of kaolin in testing chamber using the consolidation characteristic is presented herein. A slurry of kaolin was consolidated one dimensionally in a testing chamber under Overconsolidation Ratio (OCR) of ten. The moisture content and undrained shear strength were determined after the consolidation completed. It was found that, the moisture content decreases and the undrained shear strength increases with chamber depth. The differences were observed in the moisture content and strength measurements with increasing depth due to the influence of wall friction during the consolidation process. By using consolidation characteristic of kaolin from the testing chamber and Rowe cell (supplementary test), estimation of wall friction was calculated. It was found that, the wall friction estimation provided differences less than 2.2% with the experimental test

Determination of failure zone of vane shear test using artificial transparent soil

In this study, a special cylinder testing chamber equipped with vane shear device mounted at the center of the chamber base was developed to study the failure mechanism during the vane shear test. The soil was simulated using a mixture of amorphous silica and mineral oil, which becomes transparent when the refractive indices between the oil and the silica are well matched. One-dimensional consolidation method was carried out to prepare and determine the consolidation properties of the transparent soil. The vertical section aligned with the vane blade centerline was illuminated with laser light and sequence of digital images was recorded using a digital camera. Close range photogrammery and Particle Image Velocimetry (PIV) were used to determine the failure mechanism during vane shear test. Based on the contours, it can be revealed that, the failure zone is developed under a approximately a block pattern (uniform shear stress distribution) in the range 5-30% from the diameter of the blade which is closed to the conventional assumption of a uniform shear stress distribution of the failure surface

Evaluation of climate change on the collapse potential of unsaturated cement-treated laterite soil for disaster risk reduction

Extreme weather events and intense rainfall may alter the climate, which would probably affect the geotechnical constructions such as unsaturated embankments. Basically, soil moisture content determines the strength of the unsaturated soil, with wetter soils often being weaker. Although it has been proved that unsaturated condition substantially impacts the shear strength and volumetric behaviour of soil, its implications are rarely investigated or taken into account in the design. As a result, changes in temperature and rainfall loads will have an influence on geotechnical constructions and develop long-term seasonal deformations that might severely jeopardize safety and maintenance. Therefore, it is crucial to assess the effects of the climate on soil behaviour for each location through adequate geotechnical laboratory tests. Johor, Malaysia has a large area and abundant tropical soils. Hence, this study aimed to elucidate the influence of climate change on soil behaviour in the tropical regions of Johor. To impose Malaysia's climate, a series of modified suction-controlled oedometer tests are conducted under different matric suctions. The outcomes revealed that the low and high matric suction has significantly impacted the untreated and cementtreated soil. However, the great reduction of soil settlement is mostly from the coupling effect of saturation and stabiliser

Effect of cement stabilized kaolin subgrade on strength properties

Subgrade performance generally depends on the load bearing capacity of soil. This load is often affected by degree of compaction, moisture content and soil type. Poor subgrade should be avoided by removal, replace and add stabilizer agent to provide a suitable strength for subgrade. This study presents the effect of cement stabilizer on California Bearing Ratio (CBR) and Unconfined Compressive Strength (UCS) for kaolin clay in low traffic volume road. The test conducted includes determination of liquid limits which leads to plasticity index for tested sample. Standard proctor test have been conducted to determine the optimum moisture content and maximum dry density of kaolin clay by using soil stabilizer with 0, 7 and 13% of Ordinary Portland cement (OPC). The CBR and UCS was conduct to determine the strength of kaolin clay at optimum moisture content and 7 days curing period to obtain minimum strength of the soil. Finding of this study shows cement stabilizer effectively increase the strength of kaolin clay. 8 % of cement was found to be the optimum percentage of cement content value to be added into kaolin soil which complies with the Malaysia Public Work Department (PWD) specification

Investigation of tensile strength on alkaline treated and untreated kenaf geotextile under dry and wet conditions

Geosynthetics or geotextile is used for aggregate separation, soil reinforcement, filtration, drainage and moisture or liquid barriers in geotechnical applications. Because of the environmental issues, a bio-based material is introduced as a sustainable construction material. The kenaf fibre is a bio-based material available in the tropical countries. It can be potentially used as a geotextile because of its high tensile strength. This paper presents the tensile strength characteristics of kenaf geotextile, manufactured with and without sodium hydroxide (NaOH) treatment. The tensile strength of kenaf geotextile was determined by using the wide-width strip test based on the ASTM D4595-17 standard. Because the kenaf fibre has a high water absorption capability, the effect of wet and dry conditions on tensile behaviour of kenaf textile was studied. Two patterns of woven kenaf with two different opening sizes between their yarns (0 × 0 and 2 × 2 mm)—plain and incline patterns were studied. In addition, the tensile strength of the kenaf geotextiles, buried in natural ground, was examined after a one-year period. The tensile strength of kenaf geotextiles was higher for the smaller spaces between the yarns. Furthermore, the tensile strength and elongation were lower under wet condition. The alkaline treatment (6% concentration of NaOH) significantly improved the tensile strength of the woven kenaf geotextile. The tensile strength of the treated kenaf geotextile was higher than that of the untreated one, for both short and long-term conditions, showing the advantage of NaOH treatment

Evaluation of capacitor sensor performance in reinforced concrete for corrosion monitoring

In this paper, a capacitor sensor was developed with intention to detect and evaluate corrosion activity in reinforced concrete slab sample. The performance of capacitor sensor was evaluated to determine the workability of the sensor in detecting impedance pattern when embedded in concrete structure. The diameter of impedance pattern can give the polarization resistance which is useful to calculate corrosion rate for future development. This was done by detecting the impedance Nyquist plot of concrete sample. The capacitor sensor was tied to the reinforcement bar and the sample was immersed in 3.5% NaCl solution for seven days. The result shows that the capacitor sensor is fully functional in detecting impedance pattern. Hence, demonstrates potential capability of the sensor in measuring corrosion activity in concrete

Sustainable Soil Bearing Capacity Improvement Using Natural Limited Life Geotextile Reinforcement—A Review

Geotextiles are commercially made from synthetic fibres and have been used to enhance bearing capacity and to reduce the settlement of weak soil foundations. Several efforts have been made to investigate the possibility of using bio-based geotextiles for addressing environmental issues. This paper attempts to review previous studies on the bearing capacity improvement of soils reinforced with bio-based geotextiles under a vertical static load. The bearing capacity of the unreinforced foundation was used as a reference to illustrate the role of bio-based geotextiles in bearing capacity improvement. The effects of first geotextile depth to footing width ratio (d/B), geotextile spacing to footing width ratio (S/B), geotextile length to footing width ratio (L/B) and the number of reinforcement layers (N) on the bearing capacity were reviewed and presented in this paper. The optimum d/B ratio, which resulted in the maximum ultimate bearing capacity, was found to be in the range of 0.25–0.4. The optimum S/B ratio was in the range of 0.12–0.5. The most suitable L/B ratio, which resulted in better soil performance against vertical pressure, was about 3. Besides, the optimum number of layers providing the maximum bearing capacity was about three This article is useful as a guideline for a practical design and future research on the application of the natural geotextiles to improve the short-term bearing capacity of weak soil foundations in various sustainable geotechnical applications

Assessing the bond strength of hot mix asphalt pavement for wearing and binder courses

This study investigated the use of a shear box device to measure the bond condition between two layers of hot mix asphalt pavement: the wearing course and the binder course. The wearing course analysed was a Malaysian dense-graded asphaltic concrete mixture of nominal maximum aggregate 10 mm in size (AC10), which was applied over the binder course of another dense-graded asphaltic concrete mixture, AC28. A range of bond conditions was investigated by selecting various asphalt emulsions, application rates, and wearing course thicknesses based on the Malaysian standards of specification. Test results showed that interface shear strength increased as tack coat application rates and wearing course thicknesses increased. Among the tested asphalt emulsion types, a modified asphalt emulsion called RS2KL provided the highest shear resistance. Findings also show that a binder's complex shear modulus elastic portion (G*/sinδ) can affect interface shear strength for thin mixes at low rates of tack coat application

Strength and Durability of Cement-Treated Lateritic Soil

The transportation infrastructure, including low-volume roads in some regions, needs to be constructed on weak ground, implying the necessity of soil stabilization. Untreated and cement-treated lateritic soil for low-volume road suitability were studied based on Malaysian standards. A series of unconfined compressive strength (UCS) tests was performed for four cement doses (3%, 6%, 9%, 12%) for different curing times. According to Malaysian standards, the study suggested 6% cement and 7 days curing time as the optimum cement dosage and curing time, respectively, based on their 0.8 MPa UCS values. The durability test indicated that the specimens treated with 3% cement collapsed directly upon soaking in water. Although the UCS of 6% cement-treated specimens decreased against wetting–drying (WD) cycles, the minimum threshold based on Malaysian standards was still maintained against 15 WD cycles. On the contrary, the durability of specimens treated with 9% and 12% cement represented a UCS increase against WD cycles. FESEM results indicated the formation of calcium aluminate hydrate (CAH), calcium silicate hydrate (CSH), and calcium aluminosilicate hydrate (CASH) as well as shrinking of pore size when untreated soil was mixed with cement. The formation of gels (CAH, CSH, CASH) and decreasing pore size could be clarified by EDX results in which the increase in cement content increased calcium