Applied Mechanics and Materials Vols. 773-774

Abstract: Malaysia is located on the equator has resulted in having two seasons wet and dry. Both of the seasons can influence indoor air quality of buildings promoting the growth of fungal. Fungal growth can occur with the combinations of temperature, relative humidity, substrate and others. Indoor and outdoor air quality is essential for building occupants to prevent the infection diseases caused by fungal. The goal of this study is to remediate the growth indoor fungal after treated with biocides on different types of wall finishing and evaluate the efficiencies of biocides to treat indoor fungal. In this study, the biocides are utilized as a coating for coating bio-resistance. The measurements of the fungal growth are made by growing the samples on realistic wood substrates on the different wall finishing such as paints and wallpapers. The mold that grew are affecting most of the rooms is selected. The air sampler that have been used to isolate the samples of indoor fungal according to NIOSH Manual Analytical Method (NMAM 0800), a guideline provided by National Institute of Occupational Safety and Health (NIOSH). The fungal growth was evaluated using the ASTM D5590-00 standard measuring on the surface of substrate. The results show that potassium sorbate as biocide was able to reduce the indoor fungal growth depending on the type of material used in the building.

Abstract: Solid wastes varies extremely in generation rates and types of materials compositions across countries and cities or even within the city parts due to changing socio-economic and climate conditions which also differs with location and time. Thus, studies to define these parameters are essential for achieving efficiency of waste management. This paper reviewed literature and proposed a framework for the analysis of residential solid wastes generation and composition in Bauchi metropolis Nigeria, being an extract of PhD research in progress. The framework suggested a mixed approach with mainly quantitative. The framework paradigm moves toward positivism school. Case studies and stratified random technique is suggested for sample selection and Experiment and questionnaire surveys will constitute data collection instruments. SPSS software can be used for data analysis. The framework will develop reliable data base to underpin policies for efficient solid waste management in Bauchi metropolis, Nigeria.

Abstract: Piles are generally required to transfer load from a superstructure through weak or compressible strata, or through water, on to stiffer and less compressible soils and rock. The pile behavior is very important in Soil-Pile interaction (as known Kinematic Interaction) so that grouped and single pile behavior differs owing to the impacts of the pile-to-pile interaction. In this research presents a series of experimental investigations carried out on single and group pile subjected to monotonic lateral loadings. The aluminum model piles were tested in the different relative densities in Johor Bahru sand. The sand samples were prepared by using the newly designed Mobile Pluviator adopted the air pluviation method. The different configurations of model pile groups for embedded length-to-diameter ratio equal to 32 into loose and dense sand spacing from 3 to 6 pile diameter (D) were conducted. The ultimate lateral load is increased 53% in increasing of s/d from 3 to 6 owing to effects of sand relative density. A ratio of s/D more than 6d is large enough to eliminate the pile-to-pile interaction and the group effects. It may be more in the loose sand.

Abstract: Previous researchers reported that problematic soft clay can be improved by deep lime stabilization. However, due to low confining pressure of surrounding soil, problems often occurred at top part of column which reduced the performance of lime column, such as: crushing at column head and higher settlement for surrounding soil at the upper part of column. Geotextile encapsulated lime column (GELC) was proposed in this study. The stresses on column are essential in the analysis on columnar improved soil. Multi-stage loading test was conducted on lime column and GELC stabilized Pontian marine clay aged 14 days, 28 days and 56 days in order to investigate axial stress on lime column and GELC stabilized Pontian marine clay. Geotextile encapsulation increased the compressive strength of lime column about 70 percent at axial strain of 8 percent.

Abstract: The usability of the clay fraction as one of the criteria in the assessment of liquefaction susceptibility is questionable since year 2001. The use of plasticity index to replace clay fraction as a controlling parameter in the criterion is proposed. This paper aims to compare the usability of different parameter in describing the cyclic behaviour of sand-fines mixtures with various plasticity characteristics. The sand-fines mixtures were reconstituted by mixing clean sand with two types of plastic fines at different percentages by weight, at a standardized ratio of 80% of clean sand with 20% of plastic fines. All soil samples were mixed using the dry tamping method to achieve a constant relative density of 20% throughout the specimen. The soil specimens are tested with stress controlled cyclic triaxial apparatus under consolidated undrained condition, with an effective confining pressure of 100kPa. The soil specimens were considered liquefy when the value of pore pressure is equivalent to the initial cell pressure, resulting zeroes effective stress in soil specimen. The results showed that the liquefaction resistance of the sand-fines mixtures increased as the value of plasticity index increased. The plasticity index is a better indicator to describe the liquefaction susceptibility of sand-fines mixtures compare to clay content, plastic limit and activity.

Abstract: Biomediated soil improvement, a promising new branch of microbial geotechnology; which involved multi disciplines has successfully attracted abundant attentions among researchers, geotechnical engineers, and other industries practitioners. Few of the researches were conducted to examine the potential implementation of this technique on tropical residue soil. However, the uncertainties outcomes and inconsistency of bio mediated soil improvement, especially on the clayed soil have made this technique remained at the laboratory stage. Therefore, this paper intended to provide better understanding of this technique by investigating the relation between the bacteria, cementation reagents, and tropical residue soil. The residual soil was mixed with facultative anaerobe bacteria, Bacillus Subtilis before it was compacted into a prefabricated PVC mould. The soil samples were treated with different treatment condition such as (1) control or untreated, (2) treated with cementation solution, (3) treated with bacteria only, and (4) treated with bacteria and Cementation reagent. A worth noting finding showed that the sample treated with bacteria and nutrient only has produced the highest increment of shear strength. This phenomenon might have been caused by the effect of the chemical reagent to the mineralogy of residue soil. The presence of the chemical reagents is believed to have weakened the shear strength of the tropical residual soil.

Abstract: In geotechnical field, peat soil is defined as soil which is formed by accumulation of purely one hundred percent organic matter and which the distinction between soil and vegetative accumulation is not clear. The main objectives of this review paper are to summarize and compare the geochemical properties of peat soil in different districts of Sarawak. Case studies that have been chosen covered central of Sarawak up to the North of Sarawak. Geochemical properties of peat soil that being observed are pH, total carbon, organic matter, bulk density and the total nitrogen. Geochemical properties are found to be governed by the types of material inside the soil and also strongly correlated with the engineering properties of soil. Notably showed that the types of organic matter, namely fibre and/or humidified organic inside the soil will influence the soil porosity. The findings of the studies showed that geochemical properties of the peat soil in different districts of Sarawak is site dependent and could be affected by the different land use or land activities. The differences in land use and land activities affected the bulk density, pH and types of organic matter in the soil. The result indicated that peat soil land in different district can categorized as acidic soil because of the pH range is between 3.3-3.75. For the bulk density, the lowest value is recorded at the Dalat sago plantation site, which is 0.14 g/cm³. For the value of the total carbon, peat soil from the Laogan Bunut National Park is the lowest, 47.6%. Furthermore, total carbon is related to the soil organic matter, coincidentally the value of soil organic matter in Miri found to be the lowest which is 74.59%. Result for the total nitrogen, there are little difference between the district. Range of the total nitrogen is from 0.9% to 2.4%, Sibu site is getting the lowest value in this case.

Abstract: Chemical stabilizers especially calcium based stabilizer, namely lime and cement had been widely used to modify and stabilize the soil. Extensive studies were carried out by researchers to improve the effectiveness and cost-benefit of stabilizers by introducing various types of blended lime and cement. Unconfined compressive test (UCT), one of the most simple and quick strength tests, is commonly used by researchers to indicate the suitability and successfulness of newly introduced stabilizer. The aim of this study is to establish the relationship and correlation of unconfined compressive strength and tangent modulus, E at 50% of unconfined compressive strength of artificial organic soil admixed with lime zeolite. Two types of artificial organic soils, which named as Type A and Type B were prepared manually by mixing commercial kaolin with humic acid powder in different percentages. The artificial organic soils were admixed with blended lime zeolite in different ratio and cured for 7, 28 and 56 days in an oven with controlled temperature of 50°c. The strength of the materials were determined by compressing the specimens using a UCT testing frame and the tangent modulus, E50 were calculated by plotting a linear slope at 50% of ultimate strength over stress-strain curve. The findings of the study showed that the strength and E50 are strongly correlated and important as the indicator of rigidity of the material as well as its capability to resist compressive load.

Abstract: A foundation is used to support a building or structure and transmits loads directly to the underlying soil or rock. It must provide an adequate factor of safety against failure of the supporting strata, as well as failure of any excessive settlement which can interfere the function of the structure. Ultimate bearing capacity of a specific foundation is one parameter commonly used to describe the performance criteria of both the soil and the structure above. It can be improved by the inclusion of reinforcements in the ground such as geotextiles. In practice, geotextiles are normally placed directly on the soil in the form of sheet and then covered with aggregates. This research was conducted specifically to investigate the effect of different sand relative densities inside the geotextile pillow, an alternative of geotextile installations in practices, on the bearing capacity of pad foundation by laboratory experiments. A-10 cm x 10 cm pad foundation model was developed in a 1 m³ box filled with sand to actualize this experiment. Geotextile sheet was formed into a pillow, filled with sand with different relative densities and placed at a predetermined depth from the sand surface. As a result, the bearing capacity of the pad foundation model was proved to increase by 50% using a sheet of geotextile compared to the one without any geotextile. Moreover, to the same condition, the use of a geotextile pillow with different sand relative densities inside the pillow, i.e. 30%, 50% and 70% remarkably improved the bearing capacity of the pad foundation model from 150% to 525%. Among the experiment results using a geotextile pillow, the 66.67% addition of sand relative density increased the bearing capacity of a pad foundation model by 100% and 150% with 133.33% of sand relative density. It showed that the increase of the sand relative density inside the geotextile pillow was directly proportional to the increase of the bearing capacity of the pad foundation model.

Abstract: Electrokinetic Stabilisation (EKS) technique is a combination process of electroosmosis and chemical grouting. This study involves the investigation on the EKS technique performances in stabilising soft clay soils. Stabilising agents will assist the EKS technique by inducing it to the soil under direct current and its movements which is governed by the principle of electrokinetic (EK). The objective of this research is to study the effectiveness of EKS technique in increasing the strength of soft clays. Two reactors were set up by using 1.0 M of calcium chloride (CaCl₂), sodium silicate (Na₂SiO₃) as the electrolyte and stainless steel plates as the electrodes. EKS technique was being performed for 21 days period of time with a constant voltage gradient (50 V/m). This technique was carried out in two phases where the difference between them is a combination of the stabilising agent. The two combinations of stabilising agents in phase 1 and phase 2 were CaCl₂ – distilled water (DW) and CaCl₂ – Na₂SiO₃, respectively. The difference was, one was using distilled water while the other was using Na₂SiO_3. Results of the strength, liquid limit (LL), plastic limit (PL), plasticity index (PI), pH and ion concentration test towards untreated and treated soil were presented. Showing the strength of treated soil for both phases was increasing near the cathode section with 27.83 kPa and 27.67 kPa. LL and PI for treated soil showed the highest value which occurred near the cathode, while PL seems consistant with the values from untreated soil. The Calcium (Ca⁺) and sodium (Na⁺) concentrations in soil were increasing compared to the untreated soil, hence it has proven that the application of stabilisers in EK treatment is more effective in increasing the strength and the stability of soils.