Micro fine sized palm oil fuel ash (POFA) is a new supplementary cementitious material that can increase the strength, durability, and workability of concrete. However, production of this material incurs high cost and is not practical for the construction industry. This paper investigates a simple methodology of producing micro fine sized POFA by means of a laboratory scale wind tunnel system. The raw POFA obtained from an oil palm factory is first calcined to remove carbon residue and then grinded in Los Angeles abrasion machine. The grinded POFA is then blown in the fabricated wind tunnel system for separation into different ranges of particle sizes. The physical, morphological, and chemical properties of the micro fine sized POFA were then investigated using Laser Particle Size Analyser (PSA), nitrogen sorption, and Scanning Electron Microscopy with Energy Dispersive X-Ray (SEM-EDX). A total of 32.1% micro fine sized POFA were collected from each sample blown, with the size range of 1–10 micrometers. The devised laboratory scale of wind tunnel production system is successful in producing micro fine sized POFA and, with modifications, this system is envisaged applicable to be used to commercialize micro fine sized POFA production for the construction industry.
This study evaluates the workability and compressive strength properties of normal weight concrete (NWC) using high dosage of fly ash cement replacement. The goal is to find the suitable mix proportion of G40 NWC and to study the slump-loss at different interval time with fly ash replacement up to 60%. The strength properties of NWC were investigated using rebound hammer test as non-destructive and compressive strength test for verifying it. The acceptable mix proportion for fly ash replacement was then investigated using laboratory experiments. For strength properties of NWC, the samples were tested for 3, 7, 14 and 28 days. Results indicate that the inclusion of fly ash as partial cement replacement improves the workability of NWC concrete. The slump-loss of NWC with fly ash increases and it delays the setting time of fresh concrete. The strength of concrete reduces with an increment of fly ash. The strength measured using non-destructive test is lower when compared to compressive strength test. The results demonstrate that the replacement of cement with fly ash in concrete is beneficial and the targeted strength of concrete will achieve with time.
The aim of this paper is to estimate the response spectra for moderate seismic area in Sarawak, Malaysia. In the present study, the response spectra for Miri district, in Sarawak, has been obtained by using 1-D equivalent linear site response analysis at 114 borehole locations. All the borehole sites are classified based on average shear wave velocity (Vs30) as per Malaysia National Annex to Eurocode 8 (MNA-EC8) site classifications using the geotechnical relationship. In this study, the input motion was selected from Pacific Earthquake Engineering Research (PEER-NGA) online database compatible with target response spectra of Sarawak at engineering bedrock by considering the seismic hazard map for 2475 years as return period and by following the 475 years return period as shown in (MNA-EC8). From the results of this study, it was found that the maximum response spectral acceleration (response spectra with 5% damping) is 2.25 g, 3.25 g and 1.7 g at the ground surface for MNA-EC8 site classes C, D and E respectively. It was also found that the results are under the provisions of seismic design code of Malaysia. The suggested results in this study can be used as a reference in Malaysia to support the MNA-EC8.
This paper presents the evaluation of soil flexibility at the vicinity of the Bakun HEP Dam, the largest in East Malaysia. The dam is located in the Belaga District of Sarawak, approximately 50 km from the active Tubau and Bukit Mersing fault lines. This area experienced earthquakes of magnitudes ranging between 3.5 and 5.4 during the period from 1994 and 2010. This study used global and local earthquake records to evaluate the site-specific seismic hazard using a 1-D equivalent linear analysis. SPT data from 15 boreholes are utilized. Soil flexibility, factor of safety, liquefaction probability and potential index are evaluated to find the ground settlement and soil liquefaction effects. The results show that the ground amplification of Belaga District is between 2.445 and 5.146, while the peak ground accelerations (PGA) at ground surface are at a maximum average of 0.25g PGA. The soil factors for Bakun District range from 2.6 -3.0, for 2% POE in 50 years. This corresponds to a 2475-year return period. The response spectra are found matching with the target design response spectra for Sarawak as reported in the Malaysia National Annex (MS EN 1998-1:2015). The effects of soil liquefaction are found to be insignificant, as a result the nearby Bakun HEP dam is considered safe from any ground settlement. This study highlights the importance of evaluating the ability of new or existing structures in Belaga District to withstand up to 0.25g PGA in case any seismic event should occur in the future.
An understanding of the soil response to dynamic waves from the earthquakes is an important aspect of engineering safety measures against tremors. This research presents the equivalent linear site response analysis of the Miri district by using a geotechnical dataset. The main objective of this paper is to study the amplification factor for the district of Miri. Analysis of site response is critical in determining the earthquake risk and harm allocation during earthquakes. The standard penetration test ‘N’ value (SPT-N) has been used in this study. A specific soil-type relationship has been used between shear wave velocity and SPT-N value to produce profiles of shear wave velocity in each borehole site in the Miri district. For all SPT-N borehole sites, site response parameters were interpolated to produce site response maps and shear wave velocity maps in the geographical information system (GIS) environment. The research showed that the Malaysian national annex to Eurocode 8 (MNA-EC8) site class C, D and E are dominant in the Miri district. Due to the inadequacy of records of input ground motions of low-to-moderate seismicity regions, this research used an earthquake record from other locations well-matched from a target response spectrum with similar characteristics obtained from the Pacific Earthquake Engineering Research Center (PEER) online database (PEER NGA). The equivalent linear method (EQL) using DEEPSOIL is an extensively researched numeric technique that is used for assessment of site response. From the results, it has been found that the amplification ratio varies from 2.1 to 4.79 and it suggests that it is vital to study the site effect in the seismic hazard assessment of the Miri district. The work also emphasizes the relationship between seismic microzonation and site response analysis in order to reduce the adverse effects of earthquakes in Miri city by planning a proper land use.
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