The Experts below are selected from a list of 6 Experts worldwide ranked by ideXlab platform
Oliver Schwoon - One of the best experts on this subject based on the ideXlab platform.
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a new efficient and safe admixture for freeze thaw resistant concrete
2018Co-Authors: Oliver SchwoonAbstract:Frost or freeze/thaw exposure can cause serious damage to a concrete structure. De-icing salts attack concrete surfaces and are one of the most damaging causes for concrete structures. Through appropriate structural technique and observance of basic technological measures pertinent to concrete, the building material can demonstrate permanently high resistance to frost and to the strain which de-icing salt represents. One solution to increase the frost and freeze/thaw resistance is the use of an Air-entraining admixture. Air-Entrainers for concrete applications have been around for decades. Back in the last century, first trials showed that a good Air-entrainer could be made of resins refined from wood resin. In the last year decades the use of synthetic Air-Entrainers has gained momentum. The creation of artificial Air voids with natural and synthetic Air-Entrainers are based on physical effects. The Air content as well as the Air void size will be influenced positively as well as negatively by many parameters like type of admixture, chemical variations concrete raw materials, water quality, temperature, aggregates, cement, mixer type, mixing time, and many more. Recently a new type of Air-entraining admixture has been developed which entrains Air voids based on a chemical reaction, these Air-Entrainers are called as active Air-Entrainers. In contrast to the commonly used Air-entrainer, active Air-Entrainers have the advantage of producing always the same quantity and quality of Air voids required with all kind of aggregates, cements, admixtures and other influencing parameters in order to obtain finally a frost and freeze/thaw resistant concrete. The active Air-Entrainers produce even sized uniformly distributed micro Air voids throughout the concrete matrix. This paper provides general information about active Air-Entrainers, its mechanism and presents some of the laboratory and field test data.
Ethan Smith - One of the best experts on this subject based on the ideXlab platform.
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recycling and utilizing waste glass as concrete aggregate
Transportation Research Board 88th Annual MeetingTransportation Research Board, 2009Co-Authors: Farshad Rajabipour, Gregor Fischer, Porunn Sigurdardottir, Seth Goodnight, Alison Leake, Ethan SmithAbstract:Application of crushed recycled glass as concrete aggregates offers significant benefits towards sustainability by diverting waste from landfills and utilizing it in manufacturing value-added products. In areas with limited availability of durable natural aggregates, using locally recycled glass can reduce the cost and environmental impact of importing aggregates from elsewhere. However, the main challenge is the deleterious alkali-silica reactivity (ASR) of glass aggregates in concrete. To develop durable concrete products, this study evaluates the effectiveness of several ASR mitigation strategies in mortars containing recycled glass sand. The ASR mitigation methods studied include proper selection of glass type, content, and particle size, application of fly ash and lithium-based ASR inhibitors, and application of Air Entrainers, shrinkage reducers, and fiber reinforcement. The results show that recycled glass sand smaller than #30 sieve or with average particle size smaller than 0.5mm is innocuous in replacement levels as high as 50% of the natural sand. Also, ASR expansion can be effectively controlled by using 20% class F fly ash. When glass sand was used in concrete in replacement levels of up to 75%, a moderate strength reduction (5-14%) was observed. Also, the influence on fresh properties (slump and Air content) was modest. These results provide guidance on proper mixture proportioning of concrete containing recycled glass aggregates.
Farshad Rajabipour - One of the best experts on this subject based on the ideXlab platform.
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recycling and utilizing waste glass as concrete aggregate
Transportation Research Board 88th Annual MeetingTransportation Research Board, 2009Co-Authors: Farshad Rajabipour, Gregor Fischer, Porunn Sigurdardottir, Seth Goodnight, Alison Leake, Ethan SmithAbstract:Application of crushed recycled glass as concrete aggregates offers significant benefits towards sustainability by diverting waste from landfills and utilizing it in manufacturing value-added products. In areas with limited availability of durable natural aggregates, using locally recycled glass can reduce the cost and environmental impact of importing aggregates from elsewhere. However, the main challenge is the deleterious alkali-silica reactivity (ASR) of glass aggregates in concrete. To develop durable concrete products, this study evaluates the effectiveness of several ASR mitigation strategies in mortars containing recycled glass sand. The ASR mitigation methods studied include proper selection of glass type, content, and particle size, application of fly ash and lithium-based ASR inhibitors, and application of Air Entrainers, shrinkage reducers, and fiber reinforcement. The results show that recycled glass sand smaller than #30 sieve or with average particle size smaller than 0.5mm is innocuous in replacement levels as high as 50% of the natural sand. Also, ASR expansion can be effectively controlled by using 20% class F fly ash. When glass sand was used in concrete in replacement levels of up to 75%, a moderate strength reduction (5-14%) was observed. Also, the influence on fresh properties (slump and Air content) was modest. These results provide guidance on proper mixture proportioning of concrete containing recycled glass aggregates.
Gregor Fischer - One of the best experts on this subject based on the ideXlab platform.
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recycling and utilizing waste glass as concrete aggregate
Transportation Research Board 88th Annual MeetingTransportation Research Board, 2009Co-Authors: Farshad Rajabipour, Gregor Fischer, Porunn Sigurdardottir, Seth Goodnight, Alison Leake, Ethan SmithAbstract:Application of crushed recycled glass as concrete aggregates offers significant benefits towards sustainability by diverting waste from landfills and utilizing it in manufacturing value-added products. In areas with limited availability of durable natural aggregates, using locally recycled glass can reduce the cost and environmental impact of importing aggregates from elsewhere. However, the main challenge is the deleterious alkali-silica reactivity (ASR) of glass aggregates in concrete. To develop durable concrete products, this study evaluates the effectiveness of several ASR mitigation strategies in mortars containing recycled glass sand. The ASR mitigation methods studied include proper selection of glass type, content, and particle size, application of fly ash and lithium-based ASR inhibitors, and application of Air Entrainers, shrinkage reducers, and fiber reinforcement. The results show that recycled glass sand smaller than #30 sieve or with average particle size smaller than 0.5mm is innocuous in replacement levels as high as 50% of the natural sand. Also, ASR expansion can be effectively controlled by using 20% class F fly ash. When glass sand was used in concrete in replacement levels of up to 75%, a moderate strength reduction (5-14%) was observed. Also, the influence on fresh properties (slump and Air content) was modest. These results provide guidance on proper mixture proportioning of concrete containing recycled glass aggregates.
Porunn Sigurdardottir - One of the best experts on this subject based on the ideXlab platform.
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recycling and utilizing waste glass as concrete aggregate
Transportation Research Board 88th Annual MeetingTransportation Research Board, 2009Co-Authors: Farshad Rajabipour, Gregor Fischer, Porunn Sigurdardottir, Seth Goodnight, Alison Leake, Ethan SmithAbstract:Application of crushed recycled glass as concrete aggregates offers significant benefits towards sustainability by diverting waste from landfills and utilizing it in manufacturing value-added products. In areas with limited availability of durable natural aggregates, using locally recycled glass can reduce the cost and environmental impact of importing aggregates from elsewhere. However, the main challenge is the deleterious alkali-silica reactivity (ASR) of glass aggregates in concrete. To develop durable concrete products, this study evaluates the effectiveness of several ASR mitigation strategies in mortars containing recycled glass sand. The ASR mitigation methods studied include proper selection of glass type, content, and particle size, application of fly ash and lithium-based ASR inhibitors, and application of Air Entrainers, shrinkage reducers, and fiber reinforcement. The results show that recycled glass sand smaller than #30 sieve or with average particle size smaller than 0.5mm is innocuous in replacement levels as high as 50% of the natural sand. Also, ASR expansion can be effectively controlled by using 20% class F fly ash. When glass sand was used in concrete in replacement levels of up to 75%, a moderate strength reduction (5-14%) was observed. Also, the influence on fresh properties (slump and Air content) was modest. These results provide guidance on proper mixture proportioning of concrete containing recycled glass aggregates.