Concrete Waste as a Cement Replacement Material in Concrete Blocks for Optimization of Thermal and Mechanical Properties

The sustainability of the natural environment and eco-systems is of great importance. Waste generated from construction forces mankind to find new dumping grounds and at the same time, more natural resources are required for use as construction materials. In order to overcome this problem, this study was conducted to investigate the use of concrete waste in concrete blocks with a special focus on the thermal and mechanical properties of the resulting products. Three varieties of concrete mixtures were prepared, whereby they each contained different amounts of concrete waste of 0%, 5% and 15%, respectively. These mixtures were formed into cube specimens and were then analysed for data on their compressive strength, density and ultrasonic pulse. Thermal investigations were carried out on each admixture as well as on a control concrete block of model design. The thermal data results indicated that the 15% concrete waste mixture had the lowest temperature in comparison to the surrounding air. For density and compressive strength, the highest readings came from the control mixture at 2390 kg/m3 and 40.69 N/mm2, respectively, at 28 days. In terms of pulse velocity, the 5% concrete waste mixture indicated medium quality results of 4016 m/s

Assessment of Adaptive Reuse of Heritage Shop Houses for Sleep Lodging in Malaysia: Fulfilment of Conservation Guidelines

This study focuses on the compliance of adaptive reuse of historic shop houses for sleep lodging with reference to the Guidelines for Conservation Areas and Heritage Buildings by Majlis Perbandaran Pulau Pinang (MPPP). Through this research, awareness towards the compliance of building conservation guidelines for heritage shop houses will be clarified accordingly. The goal of this study is to determine and extract vital clauses and components of Guidelines for Conservation Areas and Heritage Buildings (GCAHB) towards adaptive reuse of heritage shop houses so that revitalization of these buildings can be ensured when changing the original function of the property. The aim is also to evaluate the compliance of the adaptive reuse of heritage shop houses with the GCAHB, and, lastly, to provide recommendations for adaptive reuse of heritage shop houses, also in compliance with the GCAHB. Additionally, heritage building owners can use this dissertation as a reference whenever they intend to adaptively reuse their buildings. Furthermore, recommendations in this research could be used for future reference

Evaluation of Fire Hazard and Safety Management of Heritage Buildings in Georgetown, Penang

Fire is a subject that is always neglected and ignored as far as heritage buildings are concerned. Unlike newly-built buildings, which are required under UBBL to undergo certain fire protection system tests, people are less likely to carry out such tests and detailed assessments for heritage buildings. Thus, this research is significant as it is aimed at accomplishing several objectives including studying the current fire emergency plan, besides identifying and assessing the possible fire hazards in heritage buildings in Penang. Several case studies were carried out at a few premises such as the Khoo Kongsi, Cheah Kongsi, Hock Teik Chen Shin Temple and the Teochew Temple with the aid of the Fire Rescue Department Malaysia (FRDM). The results obtained from this study will be discussed according to several aspects focusing on general health and safety management at the site, the fire-fighting system, fire exit routes and signage at the temples, fire hazards, and fire detection and alarm

Influence of co - and counter-propagating light on the phase-mismatch effect in semiconductor optical amplifiers

peer-reviewedThe phase-mismatch effect, caused by the difference in confinement factor between transverse electric (TE) and transverse magnetic (TM) modes, has not been observed in semiconductor optical amplifiers (SOAs) and is not typically accounted for. In this work, we investigate the characteristics of the phase-mismatch four wave mixing (FWM) effect, which occurs in SOA devices. Our results reveal a sinc-like response in the intensity of co- and counter-FWM conjugates as a function of the detuning shift between interacting beams. It is demonstrated that the coherence lengths between the phase match/mismatch cycles differ between co- and counter-propagating nondegenerate FWM experiments and depend on the amplified TE/TM polarizations of interacting waves aligned with respect to the birefringent axes of SOAs. The coherence lengths between each phase match/mismatch cycle in co-propagation experiments are found to be 1600 and infinite GHz, respectively, compared to 800 and 400 GHz found in counter-propagation experiments.ACCEPTEDpeer-reviewe

Low threshold linear cavity mode-locked fiber laser using microfiber-based carbon nanotube saturable absorber

In this work, we demonstrate a linear cavity mode-locked erbium-doped fiber laser in C-band wavelength region. The passive mode-locking is achieved using a microfiber-based carbon nanotube saturable absorber. The carbon nanotube saturable absorber has low saturation fluence of 0.98 µJ/cm2. Together with the linear cavity architecture, the fiber laser starts to produce soliton pulses at low pump power of 22.6 mW. The proposed fiber laser generates fundamental soliton pulses with a center wavelength, pulse width, and repetition rate of 1557.1 nm, 820 fs, and 5.41 MHz, respectively. This mode-locked laser scheme presents a viable option in the development of low threshold ultrashort pulse system for deployment as a seed laser

Investigating the Mechanical Properties of High Performance Concrete with a Steel Fibre Admixture

This paper presents the findings of an experimental investigation of the mechanical properties of concrete containing steel fibre. In the experimental investigation, the properties of steel fibre used in high strength concrete were assessed through 3 different mixes. Steel fibre was added into concrete in percentages of 0% (control), 0.6%, and 1.8%. These different types of mixes were then tested after durations of 3 days, 7 days, 14 days, and 28 days. Three cube specimens and three prism specimens were prepared for each test. In total, 36 cubes specimens and 36 prisms specimens were prepared and tested. The following tests were performed: workability test (slump test), density test, ultrasonic pulse velocity test, compressive strength test, flexural test, and water absorption test. The experimental results of this study indicate that the inclusion of steel fibres in concrete enhances the mechanical properties of high performance concrete and could reduce the severity of cracking problems for normal and high-rise buildings

Investigating the Mechanical Properties of High Performance Concrete with a Steel Fibre Admixture

This paper presents the findings of an experimental investigation of the mechanical properties of concrete containing steel fibre. In the experimental investigation, the properties of steel fibre used in high strength concrete were assessed through 3 different mixes. Steel fibre was added into concrete in percentages of 0% (control), 0.6%, and 1.8%. These different types of mixes were then tested after durations of 3 days, 7 days, 14 days, and 28 days. Three cube specimens and three prism specimens were prepared for each test. In total, 36 cubes specimens and 36 prisms specimens were prepared and tested. The following tests were performed: workability test (slump test), density test, ultrasonic pulse velocity test, compressive strength test, flexural test, and water absorption test. The experimental results of this study indicate that the inclusion of steel fibres in concrete enhances the mechanical properties of high performance concrete and could reduce the severity of cracking problems for normal and high-rise buildings

Graph Theoretic Multiple Access Interference Reduction for CDMA Based Radio LAN

In ad hoc W-CDMA wireless LANs, simultaneous transmissions between transmitter-receiver pairs generate multiple access interference (MAI), which limits the throughput. Reducing MAI increases this throughput limit. This is achieved by scheduling transmissions such that the average number of simultaneous transmissions in each frame is reduced. MAI is minimized by allowing the least interfering links to transmit together. This paper proposes a graph theoretic algorithm that groups all links into a minimum number of subsets, based on the objective of minimizing MAI in each set. Simulations show that the proposed technique achieves around 100 improvement in system capacity over the scheme where all links transmit simultaneously

Investigation of Mechanical Properties of Coconut Fiber as a Concrete Admixture

The high cost of conventional construction materials is the dominating factor affecting housing systems worldwide. Because of this, further research into alternative materials in construction is required. The purpose of this study is to experimentally investigate the physical characteristics and mechanical properties of concrete produced using shredded coconut fibre composites. The following percentage amounts of fibre were tested: 0 % (control), 0.6 %, and 1.8 %. The coconut fibres were cut to a certain length according to previous studies which suggested that the most ideal length is around 30 - 60mm. The test results showed that the compressive strength of concrete decreased as the percentage of total fibre in the concrete mix increased. The experimental results also showed that coconut fibre concrete performed satisfactorily in terms of crack growth in comparison to that of conventional concrete. Finally, it was concluded that the use of coconut fibres has great potential in the production of lightweight concrete or normal concrete for use in the construction of concrete structures. As coconut fibre is a natural material that is easily available and cheap, it is a particularly good, low-cost alternative. Therefore, this material has the potential to overcome the problem of escalating costs in the industry

Study on the Utilization of Paper Mill Sludge as Partial Cement Replacement in Concrete

A major problem arising from the widespread use of forestry biomass and processed timber waste as fuel is related to the production of significant quantities of ash as a by-product from the incineration of such biomasses. A major portion (approximately 70%) of the wood waste ash produced is land-filled as a common method of disposal. If the current trend continues with waste products, such as paper mill sludge landfills, a large amount of space would be required by 2020. A revenue study was conducted as a result of investigations into the use of paper mill sludge as recycled materials and additives in concrete mixes for use in construction projects. The study had to provide the assurance that the concrete produced had the correct mechanical strength. Concrete mixes containing paper mill sludge were prepared, and their basic strength characteristics such as the compressive strength, flexural strength, ultra pulse velocity and dynamic modulus elasticity were tested. Four concrete mixes, i.e. a control mix, and a 10%, 20%, and 30% mix of paper mill sludge as cement replacement for concrete were prepared with a DoE mix design by calculating the weight of cement, sand and aggregate. The performance of each concrete specimen was compared with the strength of the control mix. As a result, when the percentage of paper mill sludge in the concrete increased, the strength decreased. Overall, a high correlation was observed between density and strength of the concrete containing paper mill sludge