The Experts below are selected from a list of 17469 Experts worldwide ranked by ideXlab platform
Piotr Brzozowski - One of the best experts on this subject based on the ideXlab platform.
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effects of fluidal fly ash on abrasion resistance of underwater Repair Concrete
Wear, 2017Co-Authors: Elzbieta Horszczaruk, Piotr BrzozowskiAbstract:Abstract The damages of the surfaces of the hydraulic Concrete structures are usually caused by abrasive action of the debris carried by the water. The action of the debris leads also to damages of the structural reinforcement. Therefore, selection of the Repair materials is focused not only on the strength requirements, but also the abrasion resistance. On the other hand, there is very important that the majority of the Repair works is conducted under water, at great depths. Therefore, the underwater Concretes are increasingly used for the Repairs. These Concretes make possible Repairing in the contact with water, with substantially limited wash-out losses of the cement paste. In this context, the important problem is utilization of the pozzolanic materials from recycling for the production of the underwater Repair Concretes, which allows for the limitation of the cement use. In this paper, the results of the testing of the abrasion resistance of the underwater Repair Concretes were presented. The Concretes under investigation have contained 20%, 30%, 40% and 50% (of the cement mass) of the fly ashes from the fluidal beds. The fluidal fly ashes are the by-products of burning the coal in the energetic plants with the fluidal beds. Abrasion of the underwater Concretes was tested using two methods. First method consists in the use of Boehme abrasion tester, which is used in EU countries for determination of the abrasion resistance of Concrete. The second method is so-called underwater method according to the US Standard ASTM C1138. The method according to ASTM C1138 appeared to be more reliable in the evaluation of the abrasion resistance of the underwater Concretes. The highest abrasion resistance showed the Concrete with 30% (in relation to the cement mass) of the fluidal fly ashes. Due to the strong pozzolanic properties of the fluidal fly ashes, the substitution of the 30% of cement with the fluidal fly ash enables obtaining of the Concrete with improved compressive strength and abrasion resistance as well as the workability which makes possible the proper conducting of the Repair works under water.
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bond strength of underwater Repair Concretes under hydrostatic pressure
Construction and Building Materials, 2014Co-Authors: Elzbieta Horszczaruk, Piotr BrzozowskiAbstract:Abstract Complex investigation of the influence of hydrostatic pressure on the bond strength of underwater Concretes (UWC) to the Concrete substrate was carried out. A new-developed apparatus made possible to cast the Repair Concrete under water on the previously prepared Concrete substrate and use hydrostatic pressure 0.5 MPa. This pressure corresponds with placing of the Repair Concrete at the depth of 50 m. The bond strength of the Repair layers of the Concrete to horizontal and vertical surfaces was investigated; this was possible by using the specially formed Concrete substrates. The bond strength was determined using pull-off methods according to the European Standard EN 1542. Favourable effect of the pressure on the bond strength of underwater Repair Concretes was observed for the horizontal substrates. In the case of vertical substrates (a vertical wall model), however, decrease of the bond strength of UWC was observed in the layers near the water surface. The most effective method of the surface treatment during the placement of the underwater Repair Concrete under hydrostatic pressure appeared to be sand-blasting.
Yitien Chen - One of the best experts on this subject based on the ideXlab platform.
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self healing Concrete by biological substrate
Materials, 2019Co-Authors: Howji Chen, Chingfang Peng, Chaowei Tang, Yitien ChenAbstract:At present, the commonly used Repair materials for Concrete cracks mainly include epoxy systems and acrylic resins, which are all environmentally unfriendly materials, and the difference in drying shrinkage and thermal expansion often causes delamination or cracking between the original Concrete matrix and the Repair material. This study aimed to explore the feasibility of using microbial techniques to Repair Concrete cracks. The bacteria used were environmentally friendly Bacillus pasteurii. In particular, the use of lightweight aggregates as bacterial carriers in Concrete can increase the chance of bacterial survival. Once the external environment meets the growth conditions of the bacteria, the vitality of the strain can be restored. Such a system can greatly improve the feasibility and success rate of bacterial mineralization in Concrete. The test project included the microscopic testing of Concrete crack Repair, mainly to understand the crack Repair effect of lightweight aggregate Concrete with implanted bacterial strains, and an XRD test to confirm that the Repair material was produced by the bacteria. The results show that the implanted bacterial strains can undergo Microbiologically Induced Calcium Carbonate Precipitation (MICP) and can effectively fill the cracks caused by external Concrete forces by calcium carbonate deposition. According to the results on the crack profile and crack thickness, the calcium carbonate precipitate produced by the action of Bacillus pasteurii is formed by the interface between the aggregate and the cement paste, and it spreads over the entire fracture surface and then accumulates to a certain thickness to form a crack Repairing effect. The analysis results of the XRD test also clearly confirm that the white crystal formed in the Concrete crack is calcium carbonate. From the above test results, it is indeed feasible to use Bacillus pasteurii in the self-healing of Concrete cracks.
Elzbieta Horszczaruk - One of the best experts on this subject based on the ideXlab platform.
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effects of fluidal fly ash on abrasion resistance of underwater Repair Concrete
Wear, 2017Co-Authors: Elzbieta Horszczaruk, Piotr BrzozowskiAbstract:Abstract The damages of the surfaces of the hydraulic Concrete structures are usually caused by abrasive action of the debris carried by the water. The action of the debris leads also to damages of the structural reinforcement. Therefore, selection of the Repair materials is focused not only on the strength requirements, but also the abrasion resistance. On the other hand, there is very important that the majority of the Repair works is conducted under water, at great depths. Therefore, the underwater Concretes are increasingly used for the Repairs. These Concretes make possible Repairing in the contact with water, with substantially limited wash-out losses of the cement paste. In this context, the important problem is utilization of the pozzolanic materials from recycling for the production of the underwater Repair Concretes, which allows for the limitation of the cement use. In this paper, the results of the testing of the abrasion resistance of the underwater Repair Concretes were presented. The Concretes under investigation have contained 20%, 30%, 40% and 50% (of the cement mass) of the fly ashes from the fluidal beds. The fluidal fly ashes are the by-products of burning the coal in the energetic plants with the fluidal beds. Abrasion of the underwater Concretes was tested using two methods. First method consists in the use of Boehme abrasion tester, which is used in EU countries for determination of the abrasion resistance of Concrete. The second method is so-called underwater method according to the US Standard ASTM C1138. The method according to ASTM C1138 appeared to be more reliable in the evaluation of the abrasion resistance of the underwater Concretes. The highest abrasion resistance showed the Concrete with 30% (in relation to the cement mass) of the fluidal fly ashes. Due to the strong pozzolanic properties of the fluidal fly ashes, the substitution of the 30% of cement with the fluidal fly ash enables obtaining of the Concrete with improved compressive strength and abrasion resistance as well as the workability which makes possible the proper conducting of the Repair works under water.
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bond strength of underwater Repair Concretes under hydrostatic pressure
Construction and Building Materials, 2014Co-Authors: Elzbieta Horszczaruk, Piotr BrzozowskiAbstract:Abstract Complex investigation of the influence of hydrostatic pressure on the bond strength of underwater Concretes (UWC) to the Concrete substrate was carried out. A new-developed apparatus made possible to cast the Repair Concrete under water on the previously prepared Concrete substrate and use hydrostatic pressure 0.5 MPa. This pressure corresponds with placing of the Repair Concrete at the depth of 50 m. The bond strength of the Repair layers of the Concrete to horizontal and vertical surfaces was investigated; this was possible by using the specially formed Concrete substrates. The bond strength was determined using pull-off methods according to the European Standard EN 1542. Favourable effect of the pressure on the bond strength of underwater Repair Concretes was observed for the horizontal substrates. In the case of vertical substrates (a vertical wall model), however, decrease of the bond strength of UWC was observed in the layers near the water surface. The most effective method of the surface treatment during the placement of the underwater Repair Concrete under hydrostatic pressure appeared to be sand-blasting.
Bo Mattiasson - One of the best experts on this subject based on the ideXlab platform.
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Alkaliphiles : The Emerging Biological Tools Enhancing Concrete Durability
'Springer Science and Business Media LLC', 2020Co-Authors: Mamo Gashaw, Bo MattiassonAbstract:Concrete is one of the most commonly used building materials ever used. Despite it is a very important and common construction material, Concrete is very sensitive to crack formation and requires Repair. A variety of chemical-based techniques and materials have been developed to Repair Concrete cracks. Although the use of these chemical-based Repair systems are the best commercially available choices, there have also been concerns related to their use. These Repair agents suffer from inefficiency and unsustainability. Most of the products are expensive and susceptible to degradation, exhibit poor bonding to the cracked Concrete surfaces, and are characterized by different physical properties such as thermal expansion coefficients which are different to that of Concrete. Moreover, many of these Repair agents contain chemicals that pose environmental and health hazards. Thus, there has been interest in developing Concrete crack Repair agents that are efficient, long lasting, safe, and benign to the environment and exhibit physical properties which resemble that of the Concrete. The search initiated by these desires brought the use of biomineralization processes as tools in mending Concrete cracks. Among biomineralization processes, microbially initiated calcite precipitation has emerged as an interesting alternative to the existing chemical-based Concrete crack Repairing system. Indeed, results of several studies on the use of microbial-based Concrete Repair agents revealed the remarkable potential of this approach in the fight against Concrete deterioration. In addition to Repairing existing Concrete cracks, microorganisms have also been considered to make protective surface coating (biodeposition) on Concrete structures and in making self-healing Concrete. Even though a wide variety of microorganisms can precipitate calcite, the nature of Concrete determines their applicability. One of the important factors that determine the applicability of microbes in Concrete is pH. Concrete is highly alkaline in nature, and hence the microbes envisioned for this application are alkaliphilic or alkali-tolerant. This work reviews the available information on applications of microbes in Concrete: Repairing existing cracks, biodeposition, and self-healing. Moreover, an effort is made to discuss biomineralization processes that are relevant to extend the durability of Concrete structures
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alkaliphiles the emerging biological tools enhancing Concrete durability
Advances in Biochemical Engineering \ Biotechnology, 2019Co-Authors: Gashaw Mamo, Bo MattiassonAbstract:Concrete is one of the most commonly used building materials ever used. Despite it is a very important and common construction material, Concrete is very sensitive to crack formation and requires Repair. A variety of chemical-based techniques and materials have been developed to Repair Concrete cracks. Although the use of these chemical-based Repair systems are the best commercially available choices, there have also been concerns related to their use. These Repair agents suffer from inefficiency and unsustainability. Most of the products are expensive and susceptible to degradation, exhibit poor bonding to the cracked Concrete surfaces, and are characterized by different physical properties such as thermal expansion coefficients which are different to that of Concrete. Moreover, many of these Repair agents contain chemicals that pose environmental and health hazards. Thus, there has been interest in developing Concrete crack Repair agents that are efficient, long lasting, safe, and benign to the environment and exhibit physical properties which resemble that of the Concrete. The search initiated by these desires brought the use of biomineralization processes as tools in mending Concrete cracks. Among biomineralization processes, microbially initiated calcite precipitation has emerged as an interesting alternative to the existing chemical-based Concrete crack Repairing system. Indeed, results of several studies on the use of microbial-based Concrete Repair agents revealed the remarkable potential of this approach in the fight against Concrete deterioration. In addition to Repairing existing Concrete cracks, microorganisms have also been considered to make protective surface coating (biodeposition) on Concrete structures and in making self-healing Concrete.
Howji Chen - One of the best experts on this subject based on the ideXlab platform.
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self healing Concrete by biological substrate
Materials, 2019Co-Authors: Howji Chen, Chingfang Peng, Chaowei Tang, Yitien ChenAbstract:At present, the commonly used Repair materials for Concrete cracks mainly include epoxy systems and acrylic resins, which are all environmentally unfriendly materials, and the difference in drying shrinkage and thermal expansion often causes delamination or cracking between the original Concrete matrix and the Repair material. This study aimed to explore the feasibility of using microbial techniques to Repair Concrete cracks. The bacteria used were environmentally friendly Bacillus pasteurii. In particular, the use of lightweight aggregates as bacterial carriers in Concrete can increase the chance of bacterial survival. Once the external environment meets the growth conditions of the bacteria, the vitality of the strain can be restored. Such a system can greatly improve the feasibility and success rate of bacterial mineralization in Concrete. The test project included the microscopic testing of Concrete crack Repair, mainly to understand the crack Repair effect of lightweight aggregate Concrete with implanted bacterial strains, and an XRD test to confirm that the Repair material was produced by the bacteria. The results show that the implanted bacterial strains can undergo Microbiologically Induced Calcium Carbonate Precipitation (MICP) and can effectively fill the cracks caused by external Concrete forces by calcium carbonate deposition. According to the results on the crack profile and crack thickness, the calcium carbonate precipitate produced by the action of Bacillus pasteurii is formed by the interface between the aggregate and the cement paste, and it spreads over the entire fracture surface and then accumulates to a certain thickness to form a crack Repairing effect. The analysis results of the XRD test also clearly confirm that the white crystal formed in the Concrete crack is calcium carbonate. From the above test results, it is indeed feasible to use Bacillus pasteurii in the self-healing of Concrete cracks.