Properties of coal bottom ash from power plants in Malaysia and its suitability as geotechnical engineering material

Coal is one of the world’s most important sources of energy, fuelling almost 40% of electricity worldwide. Some power plants in Malaysia use coal as a raw material in generating the electricity since the year 1988. During the burning process of coal for the electricity generation, coal waste is produced which includes coal ash in the fraction of about 75 - 85 % Fly Ash (FA) and 15 - 25 % Bottom Ash (BA ) . The FA has been widely used in the cement industry but the BA is still not largely utilised in Malaysia. This might be due to the fears on the environmental hazard that might be occurred as a result of possible leaching of metal from the BA to the ground water. Research on the possible usage of BA in Geotechnical Engineering work ha s been taken place in Universiti Teknologi Malaysia since 2008 , in collaboration with the Tanjung Bin, Sultan Salahuddin Abdul Aziz Shah (or Kapar) and Sultan Azlan Shah (or Manjung) p ower plants in Johor, Selangor and Perak, respectively. This paper presents the physical, morphological, mineralogical, chemical and mechanical properties of BA and explores the possibility of using BA as alternative materials in Geotechnical Engineering works . Analysis of the results from the laboratory and physical model tests s how a huge potential of utilising this BA

Improving online teaching and learning quality in Pusat Tuisyen Seri Minda Muda

The education industry traditionally uses the Face-to-Face classroom while most students in Malaysia who desires academic excellence are accustomed to attending after-school tuition class. The unprecedented Covid-19 pandemic forced educators to shift into online classrooms, tuition centre alike. This new home-based education caused a nearly 52% reduction of total enrolled students in Pusat Tuisyen Seri Minda Muda. The exit interview disclosed that 67% of the parent were doubtful of online class effectiveness. This mixed-method action research aims to improve online teaching and learning quality in Pusat Tuisyen Seri Minda Muda through the implementation of flipped classrooms as the two-cycle intervention. In cycle one intervention, the effectiveness of teaching quality and student satisfaction is evaluated through interview sessions and survey questionnaires, respectively. Flipped classroom implemented within a total quality management framework enables repetitive learning, active participation, and timely feedback; these criteria are a better form of pedagogy in improving tutors’ teaching quality. The tutors are keen and eager to continually implement the flipped classroom as their future pedagogy. An increment of 27% secondary students is more satisfied with flipped classrooms over the online classrooms. The student’s satisfaction is in a linear function of learning quality, service quality, and student engagement. The cross-sectional study conducted in cycle two intervention proved that the students that learned through the flipped classrooms were performed 23% excellent than those who learned through the online classroom. With that, trusted that the student’s parents feel worthy of every single cent they paid. Therefore, the total enrolled student was increased from 107 to 140 students while the increment has bigger weightage on the secondary students where intervention was implemented. Generally, the intervention successfully improved teaching and learning quality, as well as increased student satisfaction and academic performance in the secondary school segment in Pusat Tuisyen Seri Minda Muda

Rapid and non-radioactive detection method of microsatellites in Mystus nemurus: a refined technique

A simple and rapid method of DNA microsatellite isolation based on the Random Amplified Microsatellites (RAMs) PCR technique was used in this study. The work presented here is part of a continuous effort in refining and perfecting the technique for more rapid, effective and optimum productivity in single locus microsatellite marker development for the River catfish, Mystus nemurus. The current refined protocol for microsatellite isolation was able to detect a total of 135 microsatellite regions resulting in 42 unique genomic sequences being submitted to GenBank. This refined technique is able to reduce the total time required from peR cloning till sequencing specific microsatellite regions to less than three and a half months

Newly developed microsatellite markers of Mystus nemurus tested for cross-species amplification in two distantly related aquacultured catfish species

The work reported here is an attempt to explore the possibility of DNA microsatellite loci transfer (cross-species amplification) to other economically important aquacultured catfish species other than its source species. A total of 25 new microsatellite loci developed for riverine catfish, Mystus nemurus were successfully cross-amplified in two distantly related catfish species within the suborder Siluroidei. Five out of the 19 loci that successfully cross-amplified in Pangasius micronemus were polymorphic, while for Clarias batrachus, cross-amplification was successful using 17 polymorphic loci. The observed heterozygosities were high for all the three catfishes. The results indicated that microsatellite loci could be as polymorphic in non-source species as in the source species

Recent trends of blended learning and flipped classroom in Malaysia

The classroom is where the student and teacher interact, while traditional education uses a Face to-Face classroom. The unprecedented COVID-19 forced education to shift into an online classroom. Still, numerous researches demonstrate that the pedagogical quality in online classrooms is thus compromised as the educators tend to convert existing face-to-face curriculum that less prioritize intellectual interaction into online ways. Blended learning is not a new yet effective teaching pedagogy, which seems suitable to overcome the challenges as mentioned above as it is a combination of traditional and online modes. Thus, this article summarizes the current trend of blended learning implementation in the Malaysian setting into valuable insight for the practitioner to redesign their pedagogy to meet new norms. This paper assessed and analyzed a total of 22 recent publications that extracted from the Web of Science Database based on three themes that are participant, instrument, and disciplinary. All researches address higher education context, mainly the students' perspectives and neglecting other stakeholders' perspectives. Blended learning is proven practical in multidisciplinary but independent curriculum, and pedagogy redevelopment is mandated. The quantitative methodology is preferable by the researcher in the identification of critical governing factors. Overall, the context of blended learning development in Malaysia remains progressively developing by time. In conclusion, the practice of blended learning implementation is getting diffused in Malaysia due to its flexibility and versatility. However, such effective pedagogy lay on collaborative efforts between various stakeholders, including educators, students, institutional management, policymakers, and parent

Numerical modeling of centrifuge test procedure for different embankment cases

Physical modelling through full-scale and small-scale models is widely implemented in order to define specific aspects of the prototype behaviour. On the other hand, numerical modeling is essentially required to cope with the complex geotechnical problems due to the ability of considering and analyzing all aspects of the model and can afford more perception about the behavior of structures such as geosynthetic-reinforced embankments. In this study, four different cases of unreinforced and reinforced embankment models constructed on soft and stiff grounds were studied. Small-scale physical modelling by means of centrifuge tests and numerical modelling by means of finite element simulations were performed. As the small-scale model was rotated in different acceleration fields during the centrifuge test, the dimensions of the centrifugal model were different from the original state of the prototype in different stages of the test. This paper focused on developing a finite element simulation based on the dimensions of a centrifugal model in different incremental acceleration fields applied during the stages of the test. Comparing the results of finite element simulations with the measurements of the centrifuge tests showed a good agreement between the two methods, which verified the reasonableness of the finite element models in analysis of embankments based on small-scale centrifugal dimensions. Moreover, the results showed the different deformation behaviour for embankments on soft and stiff grounds and indicated the significant effect of the geosyntheic reinforcement on increasing the stability of the embankment on soft ground

NUMERICAL MODELING OF CENTRIFUGE TEST PROCEDURE FOR DIFFERENT EMBANKMENT CASES

ABSTRACT: Physical modelling through full-scale and small-scale models is widely implemented in order to define specific aspects of the prototype behaviour. On the other hand, numerical modeling is essentially required to cope with the complex geotechnical problems due to the ability of considering and analyzing all aspects of the model and can afford more perception about the behavior of structures such as geosynthetic-reinforced embankments. In this study, four different cases of unreinforced and reinforced embankment models constructed on soft and stiff grounds were studied. Small-scale physical modelling by means of centrifuge tests and numerical modelling by means of finite element simulations were performed. As the small-scale model was rotated in different acceleration fields during the centrifuge test, the dimensions of the centrifugal model were different from the original state of the prototype in different stages of the test. This paper focused on developing a finite element simulation based on the dimensions of a centrifugal model in different incremental acceleration fields applied during the stages of the test. Comparing the results of finite element simulations with the measurements of the centrifuge tests showed a good agreement between the two methods, which verified the reasonableness of the finite element models in analysis of embankments based on small-scale centrifugal dimensions. Moreover, the results showed the different deformation behaviour for embankments on soft and stiff grounds and indicated the significant effect of the geosyntheic reinforcement on increasing the stability of the embankment on soft ground

Unconfined compressive strength and microstructure of clay soil stabilised with biomass silica

This study presents the Unconfined Compressive Strength (UCS) and microstructure of clay soil stabilized with locally made Biomass Silica (BS) in the form of SH-85. Since the construction of highway on soft soil raises many problems due to its low strength, understanding about the basic characteristics of soft clay and mixed with BS, play important role for improving the strength of the soft clay. The study carried out had the specific objectives to determine engineering properties of soft clay, to investigate the UCS of soft clay treated with BS and to analyze microstructure of the soft soil treated by BS with respect to various curing periods. In this study, 30 samples of clay soil were prepared under various curing periods (0, 7, 14 and 28 days) and mixed with BS at various percentages (5%, 7% and 9%). The test results show that BS can increase the strength of the clay soil. The 9% BS treated sample for 7 days curing time achieved UCS of 710 kPa. This was approximately 6 times greater than that of untreated soil strength. The highest strength was 1216 kPa at 28 days curing for soil mixed with 9% BS. The images of Scanning Electron Microscopic show that the voids of the clay would filled by the new component resulted by the reaction of BS stabilizer with the natural clay samples. This led to a continuous soil fabric resulting with stronger and denser soil

Liquefaction resistance of sand matrix soils

Numerous researches have been focusing on the roles of fines in liquefaction resistance of sand matrix soils (sand dominant soil that contains little presenting fines). It has been reported that the presence of plastic fines would either imposed additional liquefaction resistance of sand matrix soils or caused reduction to the liquefaction resistance. This paper aims to present the liquefaction resistance of sand matrix soils with respect to different fines content based on the results from cyclic tests using triaxial testing system. The sand matrix soils were reconstituted by mixing the plastic fines (kaolin and bentonite) to the clean sand at seven different percentages by weight. Results showed that liquefaction resistance of sand matrix soils decreases with an increase of fines content until a minimal value and increases thereafter. It was identified that the presence of fine contents to give the minimum liquefaction resistance were 20 % for sand-bentonite mixtures and 25 % for sand-kaolin mixtures. These values represent the threshold fines content for respective mixtures

Static response on lime column and geotextile encapsulated lime column (GELC) stabilised marine clay under vertical load

Marine clay, which is widely encountered in coastal area in Malaysia, is a problematic base material. Previous researchers reported that deep lime stabilisation can significantly improve clay. However, insufficient confining pressure from surrounding soil normally lead to the inferior performance on the upper part of column such as column head crushing and larger deformation on the surrounding soil at top part of column. Therefore, geotextile encapsulation was proposed for lime column in this study. Static response and stress distribution are essential in the understanding on behaviour of columnar stabilised soil under vertical load. Multi stages loading tests were conducted on Pontian marine clay, with and without geotextile encapsulation. Stress concentration ratio (smid/ ssoil) was examined in each loading stage, where it is defined as stress on column (smid) divided by stress on surrounding soil (ssoil). The samples were cured for 14, 28 and 56 days before tested. It was found that stress concentration ratio was dependent on column materials strength properties and applied loading. Geotextile encapsulation increased the stress concentration ratio on lime column. Stress concentration increment effect by geotextile encapsulation was further enhanced by the confining pressure of surrounding soil; however, the effect reduced with increase of applied loading. Higher stress concentration ratio indicated lesser load on surrounding soil and therefore the soil settlement could be reduced