This investigation focused on the impacts of heat production and chemical reaction on time-dependent MHD-free convective transport via a vertical permeable sheet. The ODEs are obtained by transforming the governing PDEs using similarity transformations. With the assistance of MATLAB software, the shooting technique is utilized to numerically resolve the non-dimensional governing equations with boundary conditions. The role of emerging non-dimensional parameters or numbers like the Schmidt number , heat generation parameter (Q), Prandtl number , and chemical reaction parameter (Kr) on fluid temperature, velocity, and concentration were discussed within the boundary layer. The results show that temperature and fluid motion are improved by raising the heat generating parameters. On the contrary, as the chemical reaction value goes up, the fluid velocity and concentration do as well. Journal of Engineering Science 14(2), 2023, 137-144
{"title":"Effects of Heat Generation and Chemical Reaction on Time-Dependent MHD Natural Convective Transport Past in a Vertical Perforated Sheet","authors":"Md Abu Bkar Pk","doi":"10.3329/jes.v14i2.71237","DOIUrl":"https://doi.org/10.3329/jes.v14i2.71237","url":null,"abstract":"This investigation focused on the impacts of heat production and chemical reaction on time-dependent MHD-free convective transport via a vertical permeable sheet. The ODEs are obtained by transforming the governing PDEs using similarity transformations. With the assistance of MATLAB software, the shooting technique is utilized to numerically resolve the non-dimensional governing equations with boundary conditions. The role of emerging non-dimensional parameters or numbers like the Schmidt number , heat generation parameter (Q), Prandtl number , and chemical reaction parameter (Kr) on fluid temperature, velocity, and concentration were discussed within the boundary layer. The results show that temperature and fluid motion are improved by raising the heat generating parameters. On the contrary, as the chemical reaction value goes up, the fluid velocity and concentration do as well.\u0000Journal of Engineering Science 14(2), 2023, 137-144","PeriodicalId":52570,"journal":{"name":"Journal of Engineering Science","volume":"60 14","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140487034","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Salma Katun Sela, A. K. M. Nayab Ul Hossain, Mohammad Naim Hassan, Md Humayun Kabir
In this study, blended fabric like 65% polyester 33% rayon 2% spandex was naturally dyed utilizing coffee with maintaining of all the quality parameters. In the coffee-dyed fabric, carcinogenic element like formaldehyde was not detected. The bursting strength of the fabric was unchanged after dyeing and the fabric composition was identically tantamount. The color levelness of the dyed fabric was satisfactory and the color fastness to washing rating was 4-5. Colorfastness to perspiration in both acid and alkali medium was excellent containing a rating of 4-5. The naturally dyed fabric was able to hinder the microbial effect, and the entire dyeing procedure was convenient. Due to the absence of detrimental elements, the coffee-dyed fabric could be utilized to prepare hygienic garments items; baby wears products. The main function of this article is to enhance the functional properties of traditional fabric which is improving with the utilization of natural ingredients. Journal of Engineering Science 14(2), 2023, 15-20
{"title":"Hazardous Free and Natural Colorization of Blended Fabric Utilizing Coffee with The Attainment of Acceptable Functional Properties","authors":"Salma Katun Sela, A. K. M. Nayab Ul Hossain, Mohammad Naim Hassan, Md Humayun Kabir","doi":"10.3329/jes.v14i2.71211","DOIUrl":"https://doi.org/10.3329/jes.v14i2.71211","url":null,"abstract":"In this study, blended fabric like 65% polyester 33% rayon 2% spandex was naturally dyed utilizing coffee with maintaining of all the quality parameters. In the coffee-dyed fabric, carcinogenic element like formaldehyde was not detected. The bursting strength of the fabric was unchanged after dyeing and the fabric composition was identically tantamount. The color levelness of the dyed fabric was satisfactory and the color fastness to washing rating was 4-5. Colorfastness to perspiration in both acid and alkali medium was excellent containing a rating of 4-5. The naturally dyed fabric was able to hinder the microbial effect, and the entire dyeing procedure was convenient. Due to the absence of detrimental elements, the coffee-dyed fabric could be utilized to prepare hygienic garments items; baby wears products. The main function of this article is to enhance the functional properties of traditional fabric which is improving with the utilization of natural ingredients.\u0000Journal of Engineering Science 14(2), 2023, 15-20","PeriodicalId":52570,"journal":{"name":"Journal of Engineering Science","volume":"66 40","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140486502","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-01-29DOI: 10.52326/jes.utm.2023.30(4).05
S. Zaporojan, Eugeniu Munteanu, V. Larin, Victor Pavel, Lilian Chicu
There are applications which require particular approaches for each of the used parts. The non-contact strain sensors based on microwires with positive magnetostriction requires specific technological processes starting from casting until development of the corresponding non-contact sensor device. The developed contactless sensors can be embedded into various industry critical parts which require continuous monitoring and maintenance. Hence, specific embedded devices and specific framework should be developed to provide industry reliable solution. The paper describes the technological process of casting microwires, methods of improvement casting process and stress annealing methodology used to obtain appropriate non-contact sensible elements based on microwires. Also, the paper describes the framework of using these elements in non-contact monitoring applications of the condition of specific engineering objects/structures.
{"title":"EMBEDDED DEVICES AND METHODS FOR DEVELOPMENT OF SPECIAL NON-CONTACT APPLICATIONS","authors":"S. Zaporojan, Eugeniu Munteanu, V. Larin, Victor Pavel, Lilian Chicu","doi":"10.52326/jes.utm.2023.30(4).05","DOIUrl":"https://doi.org/10.52326/jes.utm.2023.30(4).05","url":null,"abstract":"There are applications which require particular approaches for each of the used parts. The non-contact strain sensors based on microwires with positive magnetostriction requires specific technological processes starting from casting until development of the corresponding non-contact sensor device. The developed contactless sensors can be embedded into various industry critical parts which require continuous monitoring and maintenance. Hence, specific embedded devices and specific framework should be developed to provide industry reliable solution. The paper describes the technological process of casting microwires, methods of improvement casting process and stress annealing methodology used to obtain appropriate non-contact sensible elements based on microwires. Also, the paper describes the framework of using these elements in non-contact monitoring applications of the condition of specific engineering objects/structures.","PeriodicalId":52570,"journal":{"name":"Journal of Engineering Science","volume":"59 8","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140486760","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Assessment of climate change-induced precipitation and temperature changes is crucial for the adaptive and sustainable management of water resources in a country. The objective of this study is to explore the impact of climate change on future precipitation and temperature changes in the northwest region of Bangladesh using the statistical downscaling model (SDSM). In this study, Rajshahi station is taken as the case study area, and two widely applied general circulation models (GCMs), namely the Canadian Earth System Model (CanESM2) and the Hadley Center Coupled Model (HadCM3), are used for the climate change analysis. The results demonstrate that after bias correction, the CanESM2-based downscaling model performs better compared to the HadCM3-based downscaling model. The bias-corrected models for both GCMs are then employed for the projection of future precipitation and temperatures for the 2040s and 2090s, considering climate change scenarios. The precipitation trend is found to be negative for both GCMs in all scenarios. Considering the worst climate change scenarios for both GCMs (i.e., the RCP8.5 scenario in the CanESM2 and the A2 scenario in the HadCM3), the mean annual precipitation will be decreased by 9.3% and 4.5% in the 2040s and 12.1% and 4.1% in the 2090s. Furthermore, the mean annual maximum temperature will be increased by 0.233°C and 0.245°C in the 2040s and 0.468°C and 0.633°C in the 2090s, whereas the mean annual minimum temperature will be increased by 0.394°C and 0.188°C in the 2040s and 0.394°C and 0.357°C in the 2090s. Thus, the current study comes to the conclusion that decreased precipitation and increased temperatures will have an effect on the water resources in the study region, leading to a reduction in the overall supply of surface water and groundwater storage. It is expected that the study findings will help water managers and policymakers in developing a framework for sustainable and adaptive water management in the face of climate change. Journal of Engineering Science 14(2), 2023, 127-136
{"title":"Impact of Climate Change on Precipitation and Temperature Changes in the Northwest Region of Bangladesh Using SDSM: A Comparison of CanESM2 and HadCM3 Models","authors":"Md Masud Rana, Sajal Kumar Adhikary","doi":"10.3329/jes.v14i2.71236","DOIUrl":"https://doi.org/10.3329/jes.v14i2.71236","url":null,"abstract":"Assessment of climate change-induced precipitation and temperature changes is crucial for the adaptive and sustainable management of water resources in a country. The objective of this study is to explore the impact of climate change on future precipitation and temperature changes in the northwest region of Bangladesh using the statistical downscaling model (SDSM). In this study, Rajshahi station is taken as the case study area, and two widely applied general circulation models (GCMs), namely the Canadian Earth System Model (CanESM2) and the Hadley Center Coupled Model (HadCM3), are used for the climate change analysis. The results demonstrate that after bias correction, the CanESM2-based downscaling model performs better compared to the HadCM3-based downscaling model. The bias-corrected models for both GCMs are then employed for the projection of future precipitation and temperatures for the 2040s and 2090s, considering climate change scenarios. The precipitation trend is found to be negative for both GCMs in all scenarios. Considering the worst climate change scenarios for both GCMs (i.e., the RCP8.5 scenario in the CanESM2 and the A2 scenario in the HadCM3), the mean annual precipitation will be decreased by 9.3% and 4.5% in the 2040s and 12.1% and 4.1% in the 2090s. Furthermore, the mean annual maximum temperature will be increased by 0.233°C and 0.245°C in the 2040s and 0.468°C and 0.633°C in the 2090s, whereas the mean annual minimum temperature will be increased by 0.394°C and 0.188°C in the 2040s and 0.394°C and 0.357°C in the 2090s. Thus, the current study comes to the conclusion that decreased precipitation and increased temperatures will have an effect on the water resources in the study region, leading to a reduction in the overall supply of surface water and groundwater storage. It is expected that the study findings will help water managers and policymakers in developing a framework for sustainable and adaptive water management in the face of climate change.\u0000Journal of Engineering Science 14(2), 2023, 127-136","PeriodicalId":52570,"journal":{"name":"Journal of Engineering Science","volume":"53 ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140487635","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The need for smart doorbell systems has increased in recent times. This is due to the general tendency for burglars to use stealth when breaking into homes and businesses. Also, visitors are known to spend time searching for doorbells around the house. Thus, to address this problem, this paper presents a smart doorbell system that detects human presence at the door and automatically notifies the homeowner. The system consists of a microcontroller, ultrasonic sensor, GSM module, and software. When a human presence is detected within the configured range of 1 to 70cm, the ultrasonic sensor sends a signal to the microcontroller, which in turn sends a command to the GSM module to notify the homeowner. The performance of the system was tested using various parameters with results showing that the device can detect human presence within the range of 1-80cm. Journal of Engineering Science 14(2), 2023, 47-58
{"title":"An IoT-based Smart Doorbell System for Mitigating Stealth Attacks","authors":"Martins Osifeko, Godswill Iroegbu, A. Okubanjo","doi":"10.3329/jes.v14i2.71226","DOIUrl":"https://doi.org/10.3329/jes.v14i2.71226","url":null,"abstract":"The need for smart doorbell systems has increased in recent times. This is due to the general tendency for burglars to use stealth when breaking into homes and businesses. Also, visitors are known to spend time searching for doorbells around the house. Thus, to address this problem, this paper presents a smart doorbell system that detects human presence at the door and automatically notifies the homeowner. The system consists of a microcontroller, ultrasonic sensor, GSM module, and software. When a human presence is detected within the configured range of 1 to 70cm, the ultrasonic sensor sends a signal to the microcontroller, which in turn sends a command to the GSM module to notify the homeowner. The performance of the system was tested using various parameters with results showing that the device can detect human presence within the range of 1-80cm.\u0000Journal of Engineering Science 14(2), 2023, 47-58","PeriodicalId":52570,"journal":{"name":"Journal of Engineering Science","volume":"33 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140488629","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Md Shahriar Hossain, Md Tashfique Enam Tutul, Tanvir Ahmed Rifat, Mamunul Karim
This study aimed to evaluate the efficiency of the Earth Water Pipe Heat Exchanger (EWPHE) system in Bangladesh through simulation and experimental work carried out at Joypurhat in Bangladesh during the coldest period of the year, January. Additionally, the study sought to establish the method for selecting optimal installation parameters of EWPHE to increase performance and efficiency. A simulation model was made in the TRNSYS (v16.0) platform to determine the optimum values of design parameters. The simulation was run by altering its operating parameters, such as the rate of water flow, length of the pipe, built materials of the pipe, and the diameter of the underground pipeline. According to the findings, pipe burial can be done to a depth of 3.5 meters to achieve optimal output. The results of comparing four distinct materials, namely GI, Steel, PVC, and HDPE, show that these materials' characteristics do not significantly affect how well the systems perform. Additionally, as the water flow rate is increased, it is shown that the EWPHE performance is declining. According to the simulation results, it is concluded that a pipe with a length of 50 meters would be sufficient in the proposed EWPHE system to reach an average temperature decrease from 35 °C to 27 °C. Subsequently, in the field experiment, the EWPHE system had an average efficacy of 55% throughout January, which is quite promising. Journal of Engineering Science 14(2), 2023, 79-88
{"title":"Parametric Optimization and Efficiency Assessment of Horizontal Earth Water Pipe Heat Exchanger (EWPHE) in the Context of Bangladesh","authors":"Md Shahriar Hossain, Md Tashfique Enam Tutul, Tanvir Ahmed Rifat, Mamunul Karim","doi":"10.3329/jes.v14i2.71230","DOIUrl":"https://doi.org/10.3329/jes.v14i2.71230","url":null,"abstract":"This study aimed to evaluate the efficiency of the Earth Water Pipe Heat Exchanger (EWPHE) system in Bangladesh through simulation and experimental work carried out at Joypurhat in Bangladesh during the coldest period of the year, January. Additionally, the study sought to establish the method for selecting optimal installation parameters of EWPHE to increase performance and efficiency. A simulation model was made in the TRNSYS (v16.0) platform to determine the optimum values of design parameters. The simulation was run by altering its operating parameters, such as the rate of water flow, length of the pipe, built materials of the pipe, and the diameter of the underground pipeline. According to the findings, pipe burial can be done to a depth of 3.5 meters to achieve optimal output. The results of comparing four distinct materials, namely GI, Steel, PVC, and HDPE, show that these materials' characteristics do not significantly affect how well the systems perform. Additionally, as the water flow rate is increased, it is shown that the EWPHE performance is declining. According to the simulation results, it is concluded that a pipe with a length of 50 meters would be sufficient in the proposed EWPHE system to reach an average temperature decrease from 35 °C to 27 °C. Subsequently, in the field experiment, the EWPHE system had an average efficacy of 55% throughout January, which is quite promising.\u0000Journal of Engineering Science 14(2), 2023, 79-88","PeriodicalId":52570,"journal":{"name":"Journal of Engineering Science","volume":"27 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140489588","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pallab Kumar Nandi, Tahmida Tabassum, Mohiuddin Ahmad
A well-planned health monitoring system is essential for the modern health center, and a portable remote health monitoring system with many intellectual features is becoming a great improvement in healthcare arrangements. The proposed system includes various micro-electronics medical devices and applications that come through network-connected devices and help to monitor patients' real-time medical data. In this paper, the patient's health condition has been monitored by using the four types of major health parameters temperature sensor, heart pulse rate sensor, blood pressure sensor module, and blood oxygen (SpO2) sensor. All the sensor nodes are connected to the Raspberry Pi-based embedded system. The real-time health data are recorded, stored, and transmitted to the doctor via the internet with the help of a Raspberry Pi-based embedded system and IoT server. The system will benefit the patient from remote areas with quick diagnosis, remote observation, home observation, and a medical data storage system. Journal of Engineering Science 14(2), 2023, 21-30
一个规划合理的健康监测系统对于现代医疗中心来说至关重要，而一个具有多种智能功能的便携式远程健康监测系统正在极大地改善医疗保健安排。建议的系统包括各种微电子医疗设备和应用程序，它们通过网络连接设备，帮助监测病人的实时医疗数据。本文使用四种主要健康参数温度传感器、心脏脉搏传感器、血压传感器模块和血氧（SpO2）传感器监测病人的健康状况。所有传感器节点都与基于 Raspberry Pi 的嵌入式系统相连。在基于 Raspberry Pi 的嵌入式系统和物联网服务器的帮助下，实时健康数据被记录、存储并通过互联网传输给医生。该系统将为偏远地区的病人提供快速诊断、远程观察、家庭观察和医疗数据存储系统。
{"title":"Development of an IoT-Based Automatic Remote Health Monitoring System","authors":"Pallab Kumar Nandi, Tahmida Tabassum, Mohiuddin Ahmad","doi":"10.3329/jes.v14i2.71212","DOIUrl":"https://doi.org/10.3329/jes.v14i2.71212","url":null,"abstract":"A well-planned health monitoring system is essential for the modern health center, and a portable remote health monitoring system with many intellectual features is becoming a great improvement in healthcare arrangements. The proposed system includes various micro-electronics medical devices and applications that come through network-connected devices and help to monitor patients' real-time medical data. In this paper, the patient's health condition has been monitored by using the four types of major health parameters temperature sensor, heart pulse rate sensor, blood pressure sensor module, and blood oxygen (SpO2) sensor. All the sensor nodes are connected to the Raspberry Pi-based embedded system. The real-time health data are recorded, stored, and transmitted to the doctor via the internet with the help of a Raspberry Pi-based embedded system and IoT server. The system will benefit the patient from remote areas with quick diagnosis, remote observation, home observation, and a medical data storage system.\u0000Journal of Engineering Science 14(2), 2023, 21-30","PeriodicalId":52570,"journal":{"name":"Journal of Engineering Science","volume":"145 1-4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140490179","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-01-29DOI: 10.52326/jes.utm.2023.30(4).09
Mihail Mazur, V. Bulgaru, Valentin Celac, I. Şensoy, A. Ghendov-Moșanu
Nowadays there is a high concern with newly-identified protein sources to substitute all kinds of proteins derived from animals. The food industry faces a challenge to produce quality food products that can feed more than nine billion people by 2050, upholding the principles of a sustainable and environmentally affordable way. This idea can be supported by the use of legumes that stand out with appreciable protein content, rich in essential amino acids that increase the foaming and emulsifying properties as well as the dietary fiber content. In recent years, in order to solve environmental and social problems and to diversify food products to cover different nutritional types, proteins of plant origin are used to replace those of animal origin. The present work described a review about emerging alternative proteins for nutrition which focuses on its properties and characteristics.The work analyzes the influence of alternative proteins sources on the food products'sustainability.
{"title":"USE OF VEGETABLE-DERIVED PROTEINS FOR NEW FOOD PRODUCTS","authors":"Mihail Mazur, V. Bulgaru, Valentin Celac, I. Şensoy, A. Ghendov-Moșanu","doi":"10.52326/jes.utm.2023.30(4).09","DOIUrl":"https://doi.org/10.52326/jes.utm.2023.30(4).09","url":null,"abstract":"Nowadays there is a high concern with newly-identified protein sources to substitute all kinds of proteins derived from animals. The food industry faces a challenge to produce quality food products that can feed more than nine billion people by 2050, upholding the principles of a sustainable and environmentally affordable way. This idea can be supported by the use of legumes that stand out with appreciable protein content, rich in essential amino acids that increase the foaming and emulsifying properties as well as the dietary fiber content. In recent years, in order to solve environmental and social problems and to diversify food products to cover different nutritional types, proteins of plant origin are used to replace those of animal origin. The present work described a review about emerging alternative proteins for nutrition which focuses on its properties and characteristics.The work analyzes the influence of alternative proteins sources on the food products'sustainability.","PeriodicalId":52570,"journal":{"name":"Journal of Engineering Science","volume":"166 ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140485908","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Recycled concrete aggregate (RCA) is generated by crushing and processing concrete waste from demolition and construction activities, thereby reducing the environmental burden associated with disposing of concrete debris. The use of RCA in concrete production helps to alleviate the depletion of natural resources, as it serves as a substitute for traditional coarse and fine aggregates. This study identifies the microstructural aspects of RCA concrete, employing advanced techniques like scanning electron microscope (SEM) imaging with energydispersive spectroscopy (EDS) to analyze the microstructure and chemical composition of recycled concrete. The detailed microstructural analysis is anticipated to elucidate how the RCA content influences the interfacial transition zone, bond strength, and overall concrete performance. RCA exhibits a unique microstructure due to the presence of attached old mortar, which can influence the overall performance of RCA concrete. This study also explores the utilization of 100% RCA in preparing recycled concrete, comparing it with old and ordinary new concrete. The focus is on microstructural properties, hydration products, and the Interfacial Transition Zone (ITZ) between cement paste and aggregates. Samples were collected from a 47-year-old building, separating aggregates into different grades. Recycled coarse aggregates and recycled fine aggregates were obtained, and natural aggregates were collected. Concrete mixes for recycled and natural concrete were designed for a test strength of C30. Concrete cylinders were tested for compressive strength at 7, 28, and 90 days. Old concrete exhibited a dense microstructure with well-formed C-S-H gels, contributing to its superior strength. Recycled concrete, however, showed a wider and less dense ITZ, resulting in a more porous microstructure. EDS spectra confirmed C-S-H gel as the primary hydration product in all mixes, with the Ca/Si ratio varying, indicating complexity in hydrated product formation. The research highlights differences in microstructural and chemical characteristics among old concrete, ordinary new concrete, and recycled concrete. The wider ITZ and more porous microstructure in recycled concrete contribute to reduced strength. These findings provide insights into sustainable construction practices, promoting the use of recycled materials and addressing environmental challenges in the construction industry. As the construction industry continues to embrace sustainability, further research into the properties, performance, and best practices for incorporating RCA into concrete will play a pivotal role in advancing eco-friendly construction methodologies. Journal of Engineering Science 14(2), 2023, 145-155
{"title":"Micro-Characterization of Recycled Concrete Aggregate","authors":"Muhaiminul Islam Alim, Kazi Abm Mohiuddin","doi":"10.3329/jes.v14i2.71238","DOIUrl":"https://doi.org/10.3329/jes.v14i2.71238","url":null,"abstract":"Recycled concrete aggregate (RCA) is generated by crushing and processing concrete waste from demolition and construction activities, thereby reducing the environmental burden associated with disposing of concrete debris. The use of RCA in concrete production helps to alleviate the depletion of natural resources, as it serves as a substitute for traditional coarse and fine aggregates. This study identifies the microstructural aspects of RCA concrete, employing advanced techniques like scanning electron microscope (SEM) imaging with energydispersive spectroscopy (EDS) to analyze the microstructure and chemical composition of recycled concrete. The detailed microstructural analysis is anticipated to elucidate how the RCA content influences the interfacial transition zone, bond strength, and overall concrete performance. RCA exhibits a unique microstructure due to the presence of attached old mortar, which can influence the overall performance of RCA concrete. This study also explores the utilization of 100% RCA in preparing recycled concrete, comparing it with old and ordinary new concrete. The focus is on microstructural properties, hydration products, and the Interfacial Transition Zone (ITZ) between cement paste and aggregates. Samples were collected from a 47-year-old building, separating aggregates into different grades. Recycled coarse aggregates and recycled fine aggregates were obtained, and natural aggregates were collected. Concrete mixes for recycled and natural concrete were designed for a test strength of C30. Concrete cylinders were tested for compressive strength at 7, 28, and 90 days. Old concrete exhibited a dense microstructure with well-formed C-S-H gels, contributing to its superior strength. Recycled concrete, however, showed a wider and less dense ITZ, resulting in a more porous microstructure. EDS spectra confirmed C-S-H gel as the primary hydration product in all mixes, with the Ca/Si ratio varying, indicating complexity in hydrated product formation. The research highlights differences in microstructural and chemical characteristics among old concrete, ordinary new concrete, and recycled concrete. The wider ITZ and more porous microstructure in recycled concrete contribute to reduced strength. These findings provide insights into sustainable construction practices, promoting the use of recycled materials and addressing environmental challenges in the construction industry. As the construction industry continues to embrace sustainability, further research into the properties, performance, and best practices for incorporating RCA into concrete will play a pivotal role in advancing eco-friendly construction methodologies.\u0000Journal of Engineering Science 14(2), 2023, 145-155","PeriodicalId":52570,"journal":{"name":"Journal of Engineering Science","volume":"176 3-4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140490155","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Compact development is an urban development policy aimed at promoting high density mixed used city to improve city’s environmental condition. Savar is a fast-growing outer urban area of the capital Dhaka, which is growing through rapid urbanization in the recent decade. As enormous population growth causing the capital city to expand beyond city boundary, Rajdhani Unnayan Kartripakkha (RAJUK), the Capital Development Authority of the Government of Bangladesh has identified Savar as one of the five outer urban areas in the Regional Development Plan (RDP) known as Dhaka Structure Plan (2016-2035) for promoting compact development where various activities of the capital city will shift to minimize the congestion of the core city. For successful implementation of this strategy a careful investigation of the existing spatial structure of these areas is essential for guiding future urban development. Therefore, this study aims to evaluate the potential of these proposed urban areas to accommodate their future growth in a compact manner focusing on Savar, an established urban area of the Dhaka Metropolitan Region. For assessing the compact development potential of Savar, this paper analyzed six indicators of two major aspects of urban form, population and land use pattern using Geographical Information System (GIS). The results of this study revealed that the growth pattern of Savar is still not compact and efficient planning mechanism should be devised for its future growth in a sustainable manner. The findings of this study will help policymakers, planners, architects and development authorities in policymaking, planning and designing a more sustainable and efficient urban area through compact urban development at intra-urban level. Journal of Engineering Science 14(2), 2023, 107-125
{"title":"Measuring Compact Development Potential of an Emerging Urban Area: A Case of Savar","authors":"Md Muktadir Rahman","doi":"10.3329/jes.v14i2.71234","DOIUrl":"https://doi.org/10.3329/jes.v14i2.71234","url":null,"abstract":"Compact development is an urban development policy aimed at promoting high density mixed used city to improve city’s environmental condition. Savar is a fast-growing outer urban area of the capital Dhaka, which is growing through rapid urbanization in the recent decade. As enormous population growth causing the capital city to expand beyond city boundary, Rajdhani Unnayan Kartripakkha (RAJUK), the Capital Development Authority of the Government of Bangladesh has identified Savar as one of the five outer urban areas in the Regional Development Plan (RDP) known as Dhaka Structure Plan (2016-2035) for promoting compact development where various activities of the capital city will shift to minimize the congestion of the core city. For successful implementation of this strategy a careful investigation of the existing spatial structure of these areas is essential for guiding future urban development. Therefore, this study aims to evaluate the potential of these proposed urban areas to accommodate their future growth in a compact manner focusing on Savar, an established urban area of the Dhaka Metropolitan Region. For assessing the compact development potential of Savar, this paper analyzed six indicators of two major aspects of urban form, population and land use pattern using Geographical Information System (GIS). The results of this study revealed that the growth pattern of Savar is still not compact and efficient planning mechanism should be devised for its future growth in a sustainable manner. The findings of this study will help policymakers, planners, architects and development authorities in policymaking, planning and designing a more sustainable and efficient urban area through compact urban development at intra-urban level.\u0000Journal of Engineering Science 14(2), 2023, 107-125","PeriodicalId":52570,"journal":{"name":"Journal of Engineering Science","volume":"50 18","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140487444","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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