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Review on the self-healing concrete-approach and evaluation techniques
Sadam Hussain Jakhrani,Abdul Qudoos,Atta ur rehman,Hong-Gi Kim,In Kyu Jeon,Jae-Suk Ryou 한양대학교 세라믹연구소 2019 Journal of Ceramic Processing Research Vol.20 No.S1
Self-healing concrete received an attention in last few decades. This paper reviews the research conducted on self-healing inlast few decades. Self-healing approaches, different types of healing agents used, incorporating procedures, and evaluationtechniques are highlighted in this paper. The phenomenon of cracking and crack-healing, materials used for crack-healing andthe methods and techniques employed during the process, the outcomes of experiments discussed by various researchers fromtheir work are highlighted. From the literature review, it was concluded that the crack width sizes up to 0.1mm can be healedwith autogenous self-healing mechanism, whereas, crack size up to 1mm can be healed with autonomous self-healingmechanism. It was observed that the healing efficiency was wholly dependent on the concrete exposure to correspondingenvironment, the type of healing agent used, procedures and techniques followed.
고강도 모르타르의 화학적 수축을 제어하기 위한 포화상태의 재활용 차 잔류물의 활용
사담후세인 ( Sadam Hussain Jakhrani ),김홍기 ( Kim Hong-gi ),류재석 ( Ryou Jae-suk ) 한국구조물진단유지관리공학회 2019 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.23 No.2
Concrete is most widely used construction material in the world. Its superior properties make it a suitable material for utilization. Modern age concretes are more durable and have high strengths as compared to old age concretes. However, these high strength concretes presents high shrinkage at early-ages, which is due to low water/binder (w/b) ratios. Keeping in view this problem, this research study is conducted. Mortars were made with cement and silica fume as binders with incorporation of two different size ranges of tea waste particles. Setting time, flow and chemical shrinkage of fresh mortars were investigated. The results showed that the addition of saturated tea waste particles reduced the chemical shrinkage at early ages as compared to the mixes without tea waste particles.
Evaluation and future predictions of air pollutants level in Karachi city
Mukwana, Kishan Chand,Samo, Saleem Raza,Jakhrani, Abdul Qayoom,Tunio, Muhammad Mureed,Jatoi, Abdul Rehman Techno-Press 2017 Advances in environmental research Vol.6 No.2
The purpose of this study was to determine the present air pollutant concentrations and predicted levels for next 30 years in urban environment of Karachi city. For that, a total of fifty measurements were made for each twenty selected locations of the city. The locations were selected on the basis of land use pattern such as residential, commercial, industrial settlements, open areas, congested traffic and low traffic areas for investigation of air pollutants variability and intensity. The measurements were taken continuously for six months period using PM Meter, Model AEROCET 531 and Ambient Air Quality Meter, Model AAQ 7545. The concentration of air pollutants were found higher at Al Asif Square and Maripur Road due to higher intensity of traffic and at Korangi Crossing because of industrial areas. The level of pollutants was lower at Sea View owing to lower traffic congestion and transportation of pollutants by sea breezes.
Influence of Nano-silica on the Leaching Attack upon Photocatalytic Cement Mortars
Atta ur rehman,Abdul Qudoos,Sadam Hussain Jakhrani,김홍기,류재석 한국콘크리트학회 2019 International Journal of Concrete Structures and M Vol.13 No.5
Photocatalytic cementitious materials are used in the exterior of the buildings and infrastructure for self-cleaning and air-purifying purposes. These materials are exposed to the aggressive exposure conditions like acid rain, runoff water and are subjected to the deterioration due to the leaching of calcium. The knowledge of leaching attack upon photocatalytic cementitious materials after the addition of nano-materials is necessary. In the current study, the influ-ence of nano-silica addition on the leaching attack upon photocatalytic cement mortars was thoroughly investigated. For this purpose, photocatalytic mortars were made by adding 3% TiO2 and variable amount (0–2%) of nano-silica. Accelerated leaching environment was created by immersing mortars in 6 M ammonium nitrate (NH4NO3) solution. The progressive development of the leaching depth in mortars was measured. The loss of hardened properties was monitored by evaluating the compressive strength, flexural strength, porosity, and dynamic modulus of elasticity. X-ray diffraction, thermogravimetry, Fourier transform infrared spectroscopy, scanning electron microscopy tests were conducted to know the microstructural deteriorations. Results indicated that the leaching attack induced mechanical and microstructural damages in the mortars, but the addition of nano-silica decreased mechanical and microstruc-tural damages in the photocatalytic mortars and increased the resistance of photocatalytic mortars to leaching attack.
A review of the state-of-the-art in aerodynamic performance of horizontal axis wind turbine
Luhur, Muhammad Ramzan,Manganhar, Abdul Latif,Solangi, K.H.,Jakhrani, Abdul Qayoom,Mukwana, Kishan Chand,Samo, Saleem Raza Techno-Press 2016 Wind and Structures, An International Journal (WAS Vol.22 No.1
The paper presents the state-of-the-art in aerodynamic performance of the modern horizontal axis wind turbine. The study examines the different complexities involved with wind turbine blade aerodynamic performance in open atmosphere and turbine wakes, and highlights the issues which require further investigations. Additionally, the latest concept of smart blades and frequently used wind turbine design analysis tools have also been discussed. The investigation made through this literature survey shows significant progress towards wind turbine aerodynamic performance improvements in general. However, still there are several parameters whose behavior and specific role in regulating the performance of the blades is yet to be elucidated clearly; in particular, the wind turbulence, rotational effects, coupled effect of turbulence and rotation, extreme wind events, formation and life time of the wakes.
A review of the state-of-the-art in aerodynamic performance of horizontal axis wind turbine
Muhammad Ramzan Luhur,Abdul Latif Manganhar,K.H. Solangi,Abdul Qayoom Jakhrani,Kishan Chand Mukwana,Saleem Raza Samo 한국풍공학회 2016 Wind and Structures, An International Journal (WAS Vol.22 No.1
The paper presents the state-of-the-art in aerodynamic performance of the modern horizontal axis wind turbine. The study examines the different complexities involved with wind turbine blade aerodynamic performance in open atmosphere and turbine wakes, and highlights the issues which require further investigations. Additionally, the latest concept of smart blades and frequently used wind turbine design analysis tools have also been discussed. The investigation made through this literature survey shows significant progress towards wind turbine aerodynamic performance improvements in general. However, still there are several parameters whose behavior and specific role in regulating the performance of the blades is yet to be elucidated clearly; in particular, the wind turbulence, rotational effects, coupled effect of turbulence and rotation, extreme wind events, formation and life time of the wakes.
Atta ur rehman,Jeong Bae Lee,Abdul Qudoos,Sadam Hussain Jakhrani,Hong-Gi Kim,Jae-Suk Ryou 한양대학교 세라믹연구소 2019 Journal of Ceramic Processing Research Vol.20 No.3
In this study, nano titanium dioxide and nano silica have been added in white Portland cement mortars. The dosage of nano-TiO2 was fixed to 3% while the dosage of nano-SiO2 was varied from 0%-3%. Water/binder ratio was 0.45% and binder/sandratio was 1:3. The workability, water absorption, compressive and flexural strengths of mortars was measured. Thepermeability of mortars was measured using Nordest test and the carbonation resistance was measured in a carbonationchamber. The degradation of rhodamine B dye on the surface of mortars was measured after exposure of the white mortarsto the ultraviolet light. Addition of nano-SiO2 increased the compressive and flexural strengths of mortars, reduced the waterabsorption of mortars and resisted the penetration of chloride ions. The self-cleaning of the white mortars was unaffected bythe addition of nano-SiO2 particles.
Self-healing performance of coated slag aggregates in wheat straw ash blended cement composites
Jun suk Lee,Abdul Qudoos,Atta ur rehman,Hong-Gi Kim,Sadam Hussain Jakhrani,Jae-Suk Ryou 한양대학교 세라믹연구소 2019 Journal of Ceramic Processing Research Vol.20 No.4
The cracks in the concrete structures permit the ingress of harmful ions which ultimately exacerbate the durability of the structures. In addition, the environmental concern of the cement production necessitates the utilization of pozzolanic materials. This study used wheat straw ash as cement replacement material. Sodium silicate impregnated in slag aggregate, an industrial by-product, was used as the self-healing agent. The impregnated slag aggregates were coated and used as a sand replacement. Mortar samples were analyzed for compressive strength. Self-healing performance of the mortar samples was investigated via ultrasonic pulse velocity, water permeability, and dynamic modulus of elasticity tests. The results demonstrate that the addition of coated slag aggregate significantly enhanced the self-healing performance of the mortar samples. Additionally, the incorporation of wheat straw ash resulted in an increased rate of crack filling.