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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.
A tip-covered vortex generator concept to enhance film cooling on plain and curved surfaces
Sadam Hussain,Kun He,Xin Yan 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.4
Traditional film cooling with cylindrical-hole faces two challenges: (1) coolant is mainly concentrated downstream of the cooling hole center, and (2) coolant is easily lifting-off the wall at high blowing ratio conditions. Although the installation of vortex generator (VG) helps to enhance the coolant coverage, it still encounters with the limited cooling effect improvement. To solve these difficulties, this paper presents a new VG design, named tip-covered VG (TCVG), to enhance the film cooling effectiveness on the plain and curved surfaces. To demonstrate the feasibility of this design, numerical simulations are performed between the traditional film cooling with cylindrical-hole (just-hole case), film cooling with traditional VGs (TVG case), and film cooling with tip-covered VG (TCVG case). The results show that, with the TCVG, the film cooling effectiveness can be improved by 25 % and 9 % as compared with the just-hole case and TVG case, respectively.
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.
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.
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.
Muhammad Noorullah,Amina Zuberi,Muhib Zaman,Waqar Younas,Sadam Hussain,Muhammad Kamran The Korean Society of Fisheries and Aquatic Scienc 2023 Fisheries and Aquatic Sciences Vol.26 No.12
Genetic diversity serves as the basis for selecting and genetically enhancing any culturable species in aquaculture. Here, two different strains of wild (River Ravi and River Kabul) and six captive-bred strains of Labeo rohita from various provinces were se- lected, and genetic diversity among them was evaluated using three different microsatellite markers, i.e., Lr-28, Lr-29, and Lr-37, and one mitochondrial CO1 (Cytochrome c oxidase subunit 1) gene. Different strains of L. rohita were collected, and part of their caudal fin was cut and preserved in ethanol for DNA extraction and determination of genetic diversity among them. Results in- dicated that selected markers were polymorphic with polymorphic information content (PIC) content values above 0.5 with the highest in Lr-28 followed by Lr-29 and then Lr-37. The observed heterozygosity (Ho) of all strains was higher (Avg: 0.731) but less than the expected heterozygosity (He). Moreover, TMs and WRs showed the highest He, while TKs showed the lowest, He. Over- all, inbreeding coefficient (FIS) values observed for all strains with selected markers were positive. The DNA barcoding with the CO1 gene revealed genetic variation among various strains, as demonstrated by the clades in the phylogenetic tree separating the strains into two distinct clusters that then divided into sub-clusters. In conclusion, TMs showed the highest heterozygosity as compared to other strains. Overall results provide the baseline data for the initiation of the genetic improvement program.