Physical performance and durability evaluation of rubberized concrete

The main objective of this research is to develop rubberized concrete with achievable structural strength using simple mix design. Simple mix design is a description by using the crumb rubber, used as in condition just received from the plant without any washing or pre-treating procedure. Then, three types of durability test were conducted namely, 1) Chloride ion diffusion test, 2) Abrasion wear resistance test, and 3) Freezing and thawing test. Up-to-date, many successful achievements were reported by researchers around the world. However, in Asian cases, very rare information on the use of wasted as a mixture component is gathered. By conducting this study, it could provide useful and valuable knowledge for construction technology especially for Asian industry. This dissertation consists mainly of the seven chapters. In Chapter 1, the background, problem statement, significance, research contribution and novelty of this study are listed out. In Chapter 2, research review on previous researchers work on the application of waste tire rubber in mortar/concrete and durability are described. Several important properties related to this study were viewed and discussed. High reduction in strength properties was observed by previous researchers and many suggestions were proposed either by washing the rubber or the use of suitable treatment on the rubber surface in order to enhance the bonding of the matrix. However, in my research, by using conventional mixing method, it was proposed that to use the rubber without any treatment (use directly as received) with maximum 20% sand replacement in volume is a method to use crumb rubber effectively. As a result, each rubberized mixture showed an acceptable structural strength value. In Chapter 3, three step-by-step stages of mix design were conducted and discussed. The first stage was the preliminary study to determine the suitable waste tire rubber size and percentage replacement that can be used in rubberized mortar. Three rubber size group were received from the industry plant which where combination of 1mm-3mm, combination of 0.71mm-1.7mm and 0.425mm. Size of 1mm – 3mm with 10% of sand replacement was chosen in terms of acceptable fresh and hardened mortar properties. In second stage, suitable water-to-cement ratio (w/c) and required additional binder was determined before proceeding to concrete mix. Results shows that w/c = 0.35 gave reliable mortar physical properties. Finally, rubberized concrete with w/c =0.35 was carried out and specimens were prepared for mechanical test and durability test. Along these three stages, air content was carefully studied and controlled. In Chapter 4, experimental work and discussion on chloride ion diffusion in rubberized concrete tested by migration test and by immersion in salt water was described. Effective diffusion coefficient, De test was conducted according to JSCE-G571-2003. Meanwhile, immersion test in salt water was conducted according to JSCE-G572-2003. Additional concrete specimen with w/c = 0.50 was prepared to study the effectiveness of CR in high w/c in comparison with w/c = 0.35. Results showed that chloride transport characteristics were improved by increasing the amount of CR due to the fact that CR has the ability to repel water. Meanwhile, rubberized concrete with w/c = 0.35 gave better resistance against chloride ion compared to w/c = 0.50. In Chapter 5, discussion on the effectiveness of crumb rubber to improve wear resistance tested by surface abrasion test was described. An experimental study on abrasion wear resistance was conducted on mortar (w/c = 0.35, 0.30 and 0.25) and concrete (w/c = 0.35) specimen containing CR with and without silica fume. From test results, it was clearly seen that 10% crumb rubber addition as sand replacement provide good resistance against abrasion. Meanwhile, compressive strength was the most important factor affecting the abrasion resistance, where abrasion resistance was increased with an increase in compressive strength. However, abrasion resistance was found to be slightly decreased when compressive strength exceeds 50N/mm2. In Chapter 6, the role of crumb rubber as air void under freezing and thawing was studied. Specimen was prepared in three groups; first group was the specimen without silica fume with air content ranging between 4% to 5%, second group was the specimen without silica fume with air content ranging between 0% to 1.5% and third group was the specimen with silica fume with air content ranging between 4% to 5%. These rubberized concrete were tested on freezing and thawing resistance to understand this behavior. The temperature for freezing and thawing was set to 15oC ±5oC for thawing temperature and -18oC ±5oC for freezing. This test was continued until 300 cycles according to ASTM C666. Results show that up to 300 freeze-thaw cycle, there was no minus effect observed for all specimen. In Chapter 7, conclusions are drawn based on Chapter 4 to Chapter 6 and recommendations for future works is presented

Effects of the compulsory indoor confinement of organic layer poultry: a dust storm!

In August 2005 an order was issued in the Netherlands for free range poultry to be kept indoors to prevent the introduction of avian influenza. The Animal Sciences Group of Wageningen UR (Wageningen University and Research Centre) conducted a telephone survey at the start of this indoor confinement regime to establish its effects on the wellbeing of laying hens and to chart the economic consequences for the poultry keepers. The survey revealed that, according to the poultry keepers, the impact on the wellbeing of the birds was not serious, thanks to the introduction of enrichment material such as extra litter and extra feeding. And the economic consequences were confined to an increase in the amount of work associated with the special enrichment measures. To obtain a more objective picture of the consequences of the indoor confinement order, the researchers visited 37 organic layer poultry farms during November and December. Despite the rules having been relaxed, these farms were still keeping their laying hens indoors. During each visit various parameters were scored, including: strain and age of hens, dimensions and equipment of the sheds, method of ventilation, general appearance of the hens, plumage, mortality and use of enrichment material. In addition, a quantitative measurement of dust was made in the sheds. Like the first study, this follow-up study also showed that compulsory indoor confinement had not led to any serious wellbeing problems. Admittedly, the condition of the laying hens' plumage often left something to be desired, but this depended to a very large extent on the strain of hens and their age. It was not possible to say to what extent the protracted indoor confinement of the hens was responsible for the mediocre condition of their plumage, since no control observations were made on farms where indoor confinement was not imposed. Serious feather pecking was observed occasionally, but did not lead to cannibalism. No correlation could be found between the outward appearance of the laying hens and the use of enrichment materials such as straw bales, etc. As this was an observational study, it is quite possible that the use of enrichment material was frequently prompted by the existing behaviour and general condition of the animals, as a result of which farms with few such problems had less need to take extra measures. Thus, it was not possible to determine the effect of the enrichment measures on the wellbeing of the animals in this way. In general, it emerged that poultry keepers often paid extra attention to their flocks at the start of the compulsory confinement period, providing extra litter or feed as enrichment, but gradually cut back on these extra measures. The study revealed that most farms were still using laying hens whose beaks had been tipped. It is not clear to what extent the absence of major feather pecking problems can be attributed to this. Further research is needed into the impact on feather pecking of the introduction (on 1 March 2006) of a prohibition on beak-tipping in organic poultry keeping, notably when animals are compulsorily confined indoors. Particularly striking were the high dust levels measured in the sheds (average 4.5 mg/m3). It was clear that the amount of dust in the sheds was directly related to the density of the laying hens and the strain of hen. The latter may be because a placid strain of hen is less prone to scratching and scraping and thus generates less dust. In particular, sheds with a "volière" (tiered aviary) system tended to have high dust concentrations (6.9 mg/m3). Previous researchers have reported that a dust concentration above 3.7 mg/m3 is bad for animal health. In summary, it can be stated that the harmful effects associated with indoor confinement can be mitigated by giving animals more enrichment. However, this present study is unable to pronounce on the effectiveness of the individual enrichment measures. It was clear that the dust levels in the sheds where laying hens are confined are too high and that this is related, inter alia, to the system employed in the sheds

Investigation of the energy performance of a novel modular solar building envelope

The major challenges for the integration of solar collecting devices into a building envelope are related to the poor aesthetic view of the appearance of buildings in addition to the low efficiency in collection, transportation, and utilization of the solar thermal and electrical energy. To tackle these challenges, a novel design for the integration of solar collecting elements into the building envelope was proposed and discussed. This involves the dedicated modular and multiple-layer combination of the building shielding, insulation, and solar collecting elements. On the basis of the proposed modular structure, the energy performance of the solar envelope was investigated by using the Energy-Plus software. It was found that the solar thermal efficiency of the modular envelope is in the range of 41.78–59.47%, while its electrical efficiency is around 3.51% higher than the envelopes having photovoltaic (PV) alone. The modular solar envelope can increase thermal efficiency by around 8.49% and the electrical efficiency by around 0.31%, compared to the traditional solar photovoltaic/thermal (PV/T) envelopes. Thus, we have created a new envelope solution with enhanced solar efficiency and an improved aesthetic view of the entire building

The Effect of Scenario-Based Learning on 8th Grade Students’ Perceptions of Scientists

The aim of our study was to investigate the effect of scenario-based learning on eighth-grade students’ perceptions of scientists. We used a semiexperimental design to conduct our research with 36 students from the eighth grade, who were divided into experimental and control groups. We collected the data through a “Draw-a-Scientist Test,” an opinion form, and semistructured interviews. According to the findings we obtained from the drawing test, students have stereotypical perceptions of the scientists’ working environment (indoor/laboratory). But the results showed that scenario-based teaching affects eighth-grade students’ perceptions of scientists and moves them forward on two points: (1) the physical appearance of the scientist (drawing characteristics in the head area, accessories, clothing features, etc.) and (2) symbols of knowledge (encyclopedia/books/notebook, writing board) and research (test tube, magnifying glass, experiment glasses, etc.). In the light of these findings, we propose some suggestions regarding the use of scenarios in education to affect students’ perceptions of scientists