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Vacuum distribution with depth in vertical drains and soil during preloading
Khan, Abdul Qudoos,Mesri, G. Techno-Press 2014 Geomechanics & engineering Vol.6 No.4
The vacuum consolidation method which was proposed by Kjellman in 1952 has been studied extensively and used successfully since early 1980 throughout the world, especially in East and Southeast Asia. Despite the increased successful use, different opinions still exist, especially in connection to distribution of vacuum with depth and time in vertical drains and in soil during preloading of soft ground. Porewater pressure measurements from actual cases of field vacuum and vacuum-fill preloading as well as laboratory studies have been examined. It is concluded that (a) a vacuum magnitude equal to that in the drainage blanket remains constant with depth and time within the vertical drains, (b) as expected, vacuum does not develop at the same rate within the soil at different depths; however, under ideal conditions vacuum is expected to become constant with depth in soil after the end of primary consolidation, and (c) there exists a possibility of internal leakage in vacuum intensity at some sublayers of a soft clay and silt deposit. A case history of vacuum loading with sufficient subsurface information is analyzed using the ILLICON procedure.
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.
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.
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.
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 phenomena using PVA coated granules for sustainable construction
Jun Hyeong Kim,Yong-Soo Lee,Abdul Qudoos,Hong-Gi Kim,Tae Ho Ahn,Jae-Suk Ryou 한양대학교 세라믹연구소 2019 Journal of Ceramic Processing Research Vol.20 No.S1
Concrete structures are susceptible to cracking which exacerbate the durability of these structures. For this purpose, selfhealingphenomena has been introduced in the past few decades. In order to apply the granulated healing material (Granule)with PVA film coating in the concrete, cracks, which were generated by drying shrinkage, were introduced to plate-shapedconcrete specimens incorporating Granule with PVA film coating. Subsequently, healing efficiency was verified by test aboutcrack, which was subjected to the water supply. As a result, it is verified that the method by using water-soluble PVA filmcoating for maintaining self-healing efficiency of the granulated healing material will be the original approach for sustainableconcrete with self-healing capability compared with the previous method.
Nano-TiO₂ and Nano-Silica 가 함유된 모르타르의 Leaching 진행에 대한 영향성에 관한 연구
아따아르헤르만 ( Atta-ur-rehman ),압둘쿠두스 ( Abdul Qudoos ),김준형 ( Kim Jun Hyeong ),김홍기 ( Kim Hong Gi ),류재석 ( Ryou Jae Suk ) 한국구조물진단유지관리공학회 2019 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.23 No.1
In this study, cement mortars were casted using nano-silica (SiO<sub>2</sub>) and nano-titania (TiO<sub>2</sub>) as substitutes of ordinary Portland cement. Water-cement ratio was 0.40 and cement-sand ratio was 1:3. The content of nano-TiO<sub>2</sub> was 3% but the content of nano-SiO<sub>2</sub> changed in cement mortars. The content of nano-SiO<sub>2</sub> was 0%, 0.5%, 1%, 1.5% and 2% of the binder weight. Mortar prisms and beams were made in specified molds and cured in limewater. Compressive and flexural strengths, porosity and ultrasonic pulse velocity were measured. Then mortars were stored in 6 molar ammonium nitrate (NH<sub>4</sub>NO<sub>3</sub>) solution. Leaching depth, variation of mechanical and microstructural properties were measured. Presence of nano-particles decreased the leaching depth and the degradation of mechanical and microstructural properties in mortars.
Mirza, I.H.,Naqvi, M.A.,Syed, A.H.,Qudoos, A. Asian Australasian Association of Animal Productio 1990 Animal Bioscience Vol.3 No.3
Sixtyfour Baluchi lambs about 5 months of age were divided into four groups with 16 lambs each. All the animals were grazed together. Group No.1 (G-1) was kept as control i.e. on grazing only; while group No. 2 (G-2) was offered barley grain @ 200 g/head/day as supplement to grazing; Group No. 3 (G-3) was offered ad-lib urea-molasses block (UMB) with 6% cement and group No.4 (G-4) was fed ad-lib IMB having 8% cement. These UMB were fed as supplement to grazing. Experiment lasted for 105 days (July to October) in arid zone of Baluchistan. Daily per head consumption of block No.1 was found to be 92.71 g; while that of block No.2 was observed to be 90.77 g. Growth rate (g/head/day) was found to be 10, 50, 33 and 15 in G-1, G-2, G-3 and G-4 respectively. Expenditure/kg bodyweight gain was found to be rupees 12.00, 3.64 and 7.74 for G-2, G-3 and G-4 respectively.