Mechanical properties and thermal behaviour of two-stage concrete containing palm oil fuel ash

Two-stage concrete (TSC) is a special type of concrete which is made by placing coarse aggregate in a formwork and injecting a grout either by pump or under the gravity force to fill the voids. Over the decades, the application of supplementary cementing materials in conventional concrete has become widespread, and this trend is expected to continue in TSC as well. Palm oil fuel ash (POFA) is one of the ashes which has been recognized as a good pozzolanic material. This paper presents the experimental results on the performance behaviour of POFA in developing physical and mechanical properties of two-stage concrete. Four concrete mixes namely, TSC with 100% OPC as a control, and TSC with 10, 20 and 30% POFA were cast, and the temperature growth due to heat of hydration and heat transfer in the mixes was recorded. It has been found that POFA significantly reduced the temperature rise in two-stage aggregate concrete and delayed the transfer of heat to the mass of concrete. The compressive and tensile strengths, however, increased with the replacement of up to 20% POFA. The results obtained and the observation made in this study suggest that the substitution of OPC by POFA is beneficial, particularly for prepacked mass concrete where thermal cracking due to extreme heat rise is of great importance

Application of industrialized building system: a case study in Kano State, Nigeria

Development of infrastructures are needed due to the growing population, increasing demand for housing and other building activities and the improvement in the quality of life of the populace. This study has been conducted with the aim to capture the perspective of Nigerian construction industries on the industrialized building system (IBS), specifically in Kano State. The methods adopted for this study comprises of interview session with 5 expert respondents and questionnaire survey with 73 respondents of professionals within the Nigerian construction industries. Data obtained was analyzed using content, frequency and factor analysis through SPSS software. Research findings shows that majority of the construction industry in Kano are commonly practicing traditional cast on site method and IBS implementation is considered in early stage. The setback of IBS application in Kano found from this study is due to insufficient IBS manufacturer, unfamiliarity and resistance to change, enormous capital cost and lack of government interest. In order to overcome these barriers, majority of the respondents agreed that improving the educational curriculum and adopting intensive training for the related parties will help in improving IBS implementation in Kano state and indirectly to Nigeria. The study further concludes that Government support and increase awareness on IBS benefits will result in successful IBS implementation in the state

Application of industrialized building system: a case study in Kano State, Nigeria

Development of infrastructures are needed due to the growing population, increasing demand for housing and other building activities and the improvement in the quality of life of the populace. This study has been conducted with the aim to capture the perspective of Nigerian construction industries on the industrialized building system (IBS), specifically in Kano State. The methods adopted for this study comprises of interview session with 5 expert respondents and questionnaire survey with 73 respondents of professionals within the Nigerian construction industries. Data obtained was analyzed using content, frequency and factor analysis through SPSS software. Research findings shows that majority of the construction industry in Kano are commonly practicing traditional cast on site method and IBS implementation is considered in early stage. The setback of IBS application in Kano found from this study is due to insufficient IBS manufacturer, unfamiliarity and resistance to change, enormous capital cost and lack of government interest. In order to overcome these barriers, majority of the respondents agreed that improving the educational curriculum and adopting intensive training for the related parties will help in improving IBS implementation in Kano state and indirectly to Nigeria. The study further concludes that Government support and increase awareness on IBS benefits will result in successful IBS implementation in the state

Strength, modulus of elasticity and shrinkage behaviour of concrete containing waste carpet fiber

This paper presents test results on some physical and mechanical properties of concrete containing fiber from recycled carpet waste. Five concrete mixes namely plain concrete (PC) i.e. concrete without carpet fiber, as control and carpet fiber reinforced concrete (CFRC) mixes containing 0.5%, 1.0%, 1.5% and 2.0% polypropylene (PP) waste carpet fibers were made and tested for compressive, tensile and flexural strengths, modulus of elasticity and shrinkage at curing periods of 1, 7 and 28 days. It has been found that the addition of carpet fiber reduced the workability and density of concrete. Concrete containing carpet fiber exhibited lower compressive strength and modulus of elasticity than plain concrete. The carpet fibers, however, effectively improved the splitting tensile and flexural strengths of concrete. The obtained values of shrinkage revealed that the shrinkage strain of carpet fiber reinforced concrete was higher than that of plain concrete. On the basis of short-term investigation, the one-year shrinkage values of both plain concrete and concrete containing carpet fiber were also predicted by extrapolating the data obtained during this period. The results obtained in this study indicate that waste carpet fiber can suitably be used as fiber reinforcement in concrete with satisfactory performance

Behavioural response of the mud lobster, Thalassina anomala herbst, 1804 (Decapoda, Gebiidea), to different trapping devices

The behavioural response of the mud lobster, Thalassina anomala Herbst, 1804, to different trapping devices (TD), was studied in the mangrove areas of Sibuti, Sarawak, East Malaysia. Nine different TDs were deployed in this study. Observations revealed that there were no differences in response, neither due to the various types of mound, or as a result of the different TDs: rather, the lobsters either avoided, or obstructed those TDs. Detailed observations revealed that the mud lobsters showed skilled avoidance by either moving freshly dug, moist mud into the TD-types made of bamboo and plastic, or moved the fishing net out of the burrow when it was obstructed by such a type of TD. The damaged parts of the mound caused by deployment of the TD were successfully reconstructed or rebuilt by the mud lobster, using moist mud from the bottom of their tunnel. There was no particular period determined, i.e., neither by day nor at night, when the mud lobsters repaired or rebuilt their opened or otherwise disturbed burrows

Performance of a hermetic device and neem (Azadirachta indica) in storing wheat seed: Evidence from participatory household trials in central Bangladesh

Smallholder farmers in Bangladesh often use low-density polyethylene (LDPE) bags contained within woven polypropylene bags to store wheat seed during the summer monsoon that precedes winter season planting. High humidity and temperature during this period can encourage increased seed moisture and pests, thereby lowering seed quality. Following a farm household survey conducted to inform trial design, eighty farmers were engaged in an action research process in which they participated in designing and conducting trials comparing traditional and alternative seed storage methods over 30 weeks. Factorial treatments included comparison of hermetic SuperGrainbags® (Premium RZ) against LDPE bags, both with and without the addition of dried neem tree leaves (Azadirachta indica). SuperGrainbags® were more effective in maintaining seed moisture at acceptable levels close to pre-storage conditions than LDPE bags. Both seed germination and seedling coleoptile length were significantly greater in hermetic than LDPE bags. Neem had no effect on seed moisture, germination, or coleoptile length. SuperGrainbags® were also more effective in abating seed damage during storage, although inclusion of neem within LDPE bags also had significant damage. Quantification of seed predating insects and diseases suggested that SuperGrainbags® also suppressed Coleopteran pests and blackspot, the latter indicative of Fusarium graminearum. Conversely, where farmers used LDPE bags, neem also had an additional though limited pest suppressive effect. Post-storage treatment scoring by farmers revealed a strong preference for SuperGrainbags® and no preference differences for or against neem. This study demonstrates a process by which farmers can be involved in the participatory co-design and testing of alternative wheat storage options, and stresses the need to develop SuperGrainbag® supply chains so hermetic storage can be made widely available

Effects of burrowing mud lobsters (Thalassina anomala Herbst 1804) on soil macro- and micronutrients in a Malaysian mangrove

The mud lobster, genus Thalassina is the least studied taxon compared to other mud crabs within Thalassinidae family. Burrowing thalassinid populations are considered to be an effective means of bioturbation, affecting the macro- and micronutrient properties in the substrates they occur in through nutrient redistribution. This study assessed the combined effects of fresh mud excavation and old mud deposition on soil turnover and vertical marconutrients including NH4–N, NO3–N, P, K, S, Na, Ca, and Mg and micronutrients including Fe, Cu, Zn and Mn distributions in a Malaysian mangrove, Sibuti Wildlife Sanctuary, Sarawak. The mud lobster Thalassina anomala (Decapoda: Thalassinidae) inhabits and builds mounds both seafront and inland mangroves. Their burrowing activities increased NH4–N, NO3–N, P, and Na concentrations in fresh mud and Fe, Cu and Zn concentrations in the old mud. The nutrient concentrations in excavated soils were greatly affected by habitat type, and depth. Burrowing processes can effectively turnover subsurface soil to the surface, which acidifies strongly upon oxidation. Higher S content in mud lobster soil together with low pH revealed mud lobsters play a strong role in the development of acidity in the study areas. These processes could stimulate formation of acid sulphate soil in the mangroves. Therefore, bioturbation not only affects soil physical and chemical properties but also ecological functions of mangroves, and needs proper attention during restoration and reclamation programs of mangrove forests

Highly dense and chemically stable proton conducting electrolyte sintered at 1200 °C

The authors S. Hossain and A. M. Abdalla are grateful to the graduate studies office of Universiti Brunei Darussalam for graduate research scholarship (GRS) for funding this research. The authors are thankful to Professor John T. S. Irvine for managing a visiting scholarship for SH and AMA at Center for Advanced Materials at School of Chemistry in University of St Andrews, UK for the research works done.The BaCe0.7Zr0.1Y0.2−xZnxO3−δ (x = 0.05, 0.10, 0.15, 0.20) has been synthesized by the conventional solid state reaction method for application in protonic solid oxide fuel cell. The phase purity and lattice parameters of the materials have been studied by the room temperature X-ray diffraction (XRD). Scanning electron microscopy (SEM) has been done for check the morphology and grain growth of the samples. The chemical and mechanical stabilities have been done using thermogravimetric analysis (TGA) in pure CO2 environment and thermomechanical analysis (TMA) in Argon atmosphere. The XRD of the materials show the orthorhombic crystal symmetry with Pbnm space group. The SEM images of the pellets show that the samples sintered at 1200 °C are highly dense. The XRD after TGA in CO2 and thermal expansion measurements confirm the stability. The particles of the samples are in micrometer ranges and increasing Zn content decreases the size. The conductivity measurements have been done in 5% H2 with Ar in dry and wet atmospheres. All the materials show high proton conductivity in the intermediate temperature range (400–700 °C). The maximum proton conductivity was found to be 1.0 × 10−2 S cm−1 at 700 °C in wet atmosphere for x = 0.10. From our study, 10 wt % of Zn seems to be optimum at the B-site of the perovskite structure. All the properties studied here suggest it can be a promising candidate of electrolyte for IT-SOFCs.PostprintPeer reviewe

MECHANICAL PROPERTIES AND THERMAL BEHAVIOUR OF TWO-STAGE CONCRETE CONTAINING PALM OIL FUEL ASH

ABSTRACT: Two-stage concrete (TSC) is a special type of concrete which is made by placing coarse aggregate in a formwork and injecting a grout either by pump or under the gravity force to fill the voids. Over the decades, the application of supplementary cementing materials in conventional concrete has become widespread, and this trend is expected to continue in TSC as well. Palm oil fuel ash (POFA) is one of the ashes which has been recognized as a good pozzolanic material. This paper presents the experimental results on the performance behaviour of POFA in developing physical and mechanical properties of two-stage concrete. Four concrete mixes namely, TSC with 100% OPC as a control, and TSC with 10, 20 and 30% POFA were cast, and the temperature growth due to heat of hydration and heat transfer in the mixes was recorded. It has been found that POFA significantly reduced the temperature rise in two-stage aggregate concrete and delayed the transfer of heat to the mass of concrete. The compressive and tensile strengths, however, increased with the replacement of up to 20% POFA. The results obtained and the observation made in this study suggest that the substitution of OPC by POFA is beneficial, particularly for prepacked mass concrete where thermal cracking due to extreme heat rise is of great importance