| 1. |
- André, Alann, 1980, et al.
(author)
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Flax Fiber-Reinforced Glued-Laminated Timber in Tension Perpendicular to the Grain: Experimental Study and Probabilistic Analysis
- 2010
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In: Journal of materials in civil engineering. - 0899-1561 .- 1943-5533. ; 22:9, s. 827-835
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Journal article (peer-reviewed)abstract
- The weak mechanical properties of wood in tension perpendicular to the grain are often the origin of catastrophic brittle failure. In order to enhance the tension strength perpendicular to the grain and achieve a more ductile failure, flax fibre and glass fibre reinforced polymer (FRP) composites were used to strengthen glued-laminated (glulam) timber specimens. Three series of specimen of glulam timber (flax fibre reinforced, glass fibre reinforced and unreinforced), with a grand total of 28 specimens, were tested in tension perpendicular to the grain. For an approximate amount of FRP reinforcement of 1.2- in volume (thickness ~ 0.7 mm), an increase of the tensile strength up to 74- was shown, with a stiffness increase up to 41-. For all reinforced specimens, semi-ductile failures were observed. A parametric study was carried out using both the Monte Carlo method (MC) and the First Order Second Moment method (FOSM). It is shown that the mean values obtained during experiments are in agreement with those from the MC simulation. However, the standard deviations from the MC simulation are larger. From the FOSM analysis, it is demonstrated that the variation in glulam stiffness perpendicular to the grain is not the first parameter driving the variation for the reinforced system. The variation in mechanical properties of the flax fibres appeared to be the driving parameters for the strength of the system.
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| 2. |
- Williams Portal, Natalie, 1986, et al.
(author)
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Sustainable Potential of Textile-Reinforced Concrete
- 2015
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In: Journal of Materials in Civil Engineering. - 1943-5533 .- 0899-1561. ; 27:7
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Journal article (peer-reviewed)abstract
- The building construction industry is in need of sustainable materials and solutions. A novel building material, such as textile-reinforced concrete (TRC), could be used to meet this demand. TRC is a combination of fine-grained concrete and multi-axial textile fabrics, which has been fundamentally researched over the past decade. TRC-based research has explored various facets of this composite material, such as its structural functionality, production, applicability and design. One key aspect that is still missing, however, is a comprehensive review of the sustainable potential of this material in terms of its input-output and durability which suitably answers to requirement no.7 of EU’s Construction Products Regulation. This article provides qualitative and quantitative evaluation of the sustainable potential and prospective development of TRC particularly reinforced by alkali-resistant (AR) glass, carbon or basalt fibers. Based on the outcome of this evaluation, carbon textile fibers were observed to hold the optimal potential mechanical behavior; additionally, it was revealed through the conducted Life Cycle Assessment (LCA), that basalt had the least cumulative energy demand while carbon had the least environmental impact.
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| 3. |
- Johannesson, Björn, et al.
(author)
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Test of four different experimental methods to determine sorption isotherms
- 2002
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In: Journal of Materials in Civil Engineering. - 0899-1561 .- 1943-5533. ; 14:6, s. 471-477
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Journal article (peer-reviewed)abstract
- One important property of materials is their moisture fixation capacity, i.e., their ability to hold moisture at different relative humidities. The sorption isotherm is one of the main input data in moisture diffusion models, and it can also be used to evaluate properties of the microstructure. We have used four different methods to measure the sorption isotherm of sandstone and porous glass. The first method was to equilibrate samples over saturated salt solutions. The second was a sorption balance in which small material samples were weighed as they were exposed to different relative humidities. The third method was the pressure plate extractor, in which a totally wet sample was equilibrated at various overpressures, corresponding to certain relative humidities. The fourth method was a newly developed microcalorimetric technique to measure sorption isotherms. Despite the different natures of the methods, a satisfying agreement was found. (10 refs.)
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| 4. |
- Bekele, Abiy, et al.
(author)
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Application of Energy-Based Crack Initiation Approach to Low-Temperature Damage and Recovery Based on Noncontact Resonance Testing
- 2020
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In: Journal of materials in civil engineering. - : American Society of Civil Engineers (ASCE). - 0899-1561 .- 1943-5533. ; 32:9
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Journal article (peer-reviewed)abstract
- Low temperature has a tendency to cause microdamage in asphalt concrete because of the relative thermal contraction of mastic and subsequent accumulation of thermal stresses. This paper presents the applicability of an energy-based micromechanical approach for assessing low-temperature damage and recovery in asphalt concrete based on a newly developed noncontact resonance testing. The principle of local energy balance and redistribution was applied to estimate average thermal microcrack length by considering local thermal strain energy release zones and surface energy of cracks initiated at preexisting air voids. A damage probing test was carried out by thermal loading and unloading of five different asphalt concrete specimens. The test was carried out by using a recently developed noncontact resonance method. The stiffness modulus was determined from the resonance test and utilized in the energy balance and redistribution formulation. Coefficients of thermal contraction of the specimens were also determined based on the noncontact resonance test and by applying the principle of the impact-echo method and calculating changes in thickness of the test specimens.
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| 5. |
- Bhanbhro, Riaz, et al.
(author)
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Mechanical Properties and Particle Breakage of Uniform-Sized Tailings Material
- 2021
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In: Journal of materials in civil engineering. - Luleå : American Society of Civil Engineers (ASCE). - 0899-1561 .- 1943-5533. ; 33:3
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Journal article (peer-reviewed)abstract
- Tailings dam disasters are reported almost every year and are triggered by mechanisms, such as overtopping, piping, and others.The failures due to inadequate management cannot be neglected as well. These dams are constructed mostly in a step-by-step constructionmethod that leads to a continuously changing state of vertical loads during construction and may lead to particle breakage and changes instrength. Therefore, a layer of tailings dam today may not be the same tomorrow during the construction phase. To study the effects ofdifferent loads on particle breakage and strength, direct shear tests were performed on remolded tailings samples that were separated intodifferent particle sizes. The tests were performed using different normal stresses that ranged from 50 to 500 kPa. The results indicate that finertailings exhibited slightly more shear resistance than that of coarser tailings irrespective of the deposition method. For normally depositedspecimen, the dilatant and contractant behavior in vertical height was observed when the normal effective stress was less than 300 kPa andgreater than 300 kPa, respectively. Under the vertical deposition method, the finer tailings showed contractant height behavior when subjectedto a normal effective stress of 300 kPa. The friction angle and the cohesion of vertically deposited specimens were slightly higher and slightlylower, respectively, than that of normally deposited ones. The breakage of tailings particles was observed to be proportional to the particle sizeof the tailings.
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| 6. |
- Buasiri, Thanyarat, et al.
(author)
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State of the Art on Sensing Capability of Poorly or Nonconductive Matrixes with a Special Focus on Portland Cement–Based Materials
- 2019
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In: Journal of materials in civil engineering. - : American Society of Civil Engineers (ASCE). - 0899-1561 .- 1943-5533. ; 31:11
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Journal article (peer-reviewed)abstract
- Concrete is a well-established and the most used but also well-characterized building material in the world. However, many old and new-build structures suffer from premature failures due to extensive deterioration and decreased load-bearing capacity. Consequently, structural monitoring systems are essential to ensure safe usage of concrete structures within and beyond the designed life. Traditional monitoring systems are based on metallic sensors installed in crucial locations throughout the structure. Unfortunately, most of them have a relatively low reliability and very short life span when exposed to often very harsh environments. The ideal solution is therefore to develop a smart concrete having itself self-sensing capability. A number of studies show that conductive cementitious matrixes will undergo changes in their electrical resistivity with variations of stresses, strains or, developing microcracking. This can be used as a reliable tool to measure changes. This review provides a comprehensive overview of several non-conductive matrixes, with special focus on Portland cement based materials showing self-sensing capabilities by description of detection mechanisms, sensing capabilities, limitations and potential applications.
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| 7. |
- Cwirzen, Andrzej, et al.
(author)
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Effect of baltic seawater and binder type on frost durability of concrete
- 2014
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In: Journal of materials in civil engineering. - 0899-1561 .- 1943-5533. ; 26:2, s. 275-282
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Journal article (peer-reviewed)abstract
- The effects of Baltic seawater on frost durability of PC concretes using sulfate resistant portland cement and combination of rapid hardening portland cement with silica fume were studied. The freeze-thaw cycles were performed on specimens exposed to the Baltic seawater, 3% sodium chloride solution and deionized water. The freeze-thaw cycles appeared to cause the most extensive internal damage in specimens based on sulfate resistant cement (SR) and exposed to seawater. The most extensive surface scaling was observed in the case of concretes containing silica fume and exposed to deicing salts. Based on the thermo gravimetric and X-ray diffraction analyses it was concluded that extensive internal damage of concrete based on SR was caused by changes of the microstructure due to secondary formation of ettringite, carbonation, and formation of calcite. The results showed also that low C3A content of the SR did not fully mitigate formation of secondary ettringite during freeze-thaw cycles. A combination of rapid hardening portland cement and silica fume appeared to form more frost resistant concrete when exposed to seawater. © 2014 American Society of Civil Engineers.
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| 8. |
- Cwirzen, Andrzej, et al.
(author)
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Effects of reactive magnesia on microstructure and frost durability of portland cement-based binders
- 2013
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In: Journal of materials in civil engineering. - 0899-1561 .- 1943-5533. ; 25:12, s. 1941-1950
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Journal article (peer-reviewed)abstract
- The effects of portland cement (PC) replacement with magnesia (reactive magnesium-oxide) on properties of PC-based pastes, mortars, and concretes were investigated. The research included determination of mechanical properties and frost durability in addition to studies of the microstructure and microchemistry. The mortar and paste mixtures contained from 10-80 weight percent (wt%) replacement of PC by magnesia and had water to cementitious-binder ratios from 0.4-0.7, whereas concretes contained from 5-10 wt% magnesia and had a water to cementitious-binder ratio of 0.53. Replacement of PC by magnesia had adverse effects on the mechanical properties and frost durability. The magnesia reduced microcracking of the binder matrix in comparison with pastes containing only PC. The primary hydration product of magnesia was brucite in addition to regular hydration phases of PC. The amount of formed portlandite was increased. Magnesia caused densification of the microstructure but also increased the capillary porosity, resulting in lower frost-durability. © 2013 American Society of Civil Engineers.
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| 9. |
- Edvardsson, Karin, et al.
(author)
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Impact of fine materials content on the transport of dust suppressants in gravel road wearing courses
- 2011
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In: Journal of materials in civil engineering. - 0899-1561 .- 1943-5533. ; 23:8, s. 1163-1170
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Journal article (peer-reviewed)abstract
- A significant problem when dust-suppressing agents are used on gravel roads is that they tend to leach during rainfall. The purpose of this study is to illustrate this problem by using laboratory studies and studies in situ. Both capillary rise and leaching of suppressants were examined by using cylinders filled with wearing course material. Chloride was more prone than lignosulphonate to transport upwards by means of capillary rise, and therefore, it showed a more effective performance over a longer period of time. Optimal percentages of fine material for minimal lignosulphonate and chloride leaching were found to be 15% by weight and 10-15% by weight, respectively. Ions of calcium chloride seemed to flocculate clay particles, which probably prevents them from leaching. To study the in situ longevity of fine material in general, calcium carbonate, mesa, was used as a marker. The fine material in gravel wearing courses must be replenished regularly. Mesa loss was up to 80% after 1 year.
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| 10. |
- Gschösser, Florian, et al.
(author)
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Life-Cycle Assessment of the Production of Swiss Road Materials
- 2012
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In: Journal of Materials in Civil Engineering. - 1943-5533 .- 0899-1561. ; 23:2, s. 168-176
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Journal article (peer-reviewed)abstract
- Sustainable development demands contributions across all economic sectors. Thus, the infrastructure field, in this case road infrastructure, also has to contribute its part by generating road materials and road construction with lower environmental impacts. This paper analyzes the environmental potentials hidden in road materials used in Swiss road pavements. For several materials used in road construction, cradle-to-gate life-cycle assessments (LCA) were performed, taking into account all environmental impacts from raw material extraction to the finished product at the production plant. Environmental improvement potentials were analyzed for the production of asphalt mixtures, concrete mixtures, and subbase mixtures, using eight different environmental impact indicators. The results show differences in the environmental impact between best case and current status production setup of up to 54% for asphalt mixtures, 38% for concrete mixtures, and 93% for subbase mixtures.
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