The Experts below are selected from a list of 5163 Experts worldwide ranked by ideXlab platform

Randy Turpin - One of the best experts on this subject based on the ideXlab platform.

  • potential applications of phase change materials in Concrete Technology
    Cement & Concrete Composites, 2007
    Co-Authors: Dale P Bentz, Randy Turpin
    Abstract:

    In internal curing, pre-wetted lightweight aggregates (LWA) serve as internal reservoirs to supply the extra water needed by the cementitious and pozzolanic components of the Concrete during their hydration processes. Due to their porous nature and reasonably high absorption capacity, the LWA can also be filled with other materials, such as phase change materials (PCMs). In this paper, three potential applications of PCM-filled LWA in Concrete Technology are presented. In addition to the previously explored application of increasing the energy storage capacity of Concrete in residential and commercial construction by using a PCM with a transition temperature near room temperature, applications for higher and lower temperature PCMs also exist. In the former case, a PCM can be used to reduce the temperature rise (and subsequent rate of temperature decrease) of a large Concrete section during (semi)adiabatic curing, to minimize thermal cracking, etc. In the latter case, a PCM can perhaps reduce the number or intensity of freeze/thaw cycles experienced by a bridge deck or other Concrete exposed to a winter environment. In this paper, these latter two applications are preliminarily explored from both experimental and modeling viewpoints.

  • Potential applications of phase change materials in Concrete Technology
    Cement and Concrete Composites, 2007
    Co-Authors: Dp Bentz, Randy Turpin
    Abstract:

    In internal curing, pre-wetted lightweight aggregates (LWA) serve as internal reservoirs to supply the extra water needed by the cementitious and pozzolanic components of the Concrete during their hydration processes. Due to their porous nature and reasonably high absorption capacity, the LWA can also be filled with other materials, such as phase change materials (PCMs). In this paper, three potential applications of PCM-filled LWA in Concrete Technology are presented. In addition to the previously explored application of increasing the energy storage capacity of Concrete in residential and commercial construction by using a PCM with a transition temperature near room temperature, applications for higher and lower temperature PCMs also exist. In the former case, a PCM can be used to reduce the temperature rise (and subsequent rate of temperature decrease) of a large Concrete section during (semi)adiabatic curing, to minimize thermal cracking, etc. In the latter case, a PCM can perhaps reduce the number or intensity of freeze/thaw cycles experienced by a bridge deck or other Concrete exposed to a winter environment. In this paper, these latter two applications are preliminarily explored from both experimental and modeling viewpoints. © 2007 Elsevier Ltd. All rights reserved.

Miguel Jose Oliveira - One of the best experts on this subject based on the ideXlab platform.

  • mitigation of the negative effects of recycled aggregate water absorption in Concrete Technology
    Construction and Building Materials, 2017
    Co-Authors: Matthias Eckert, Miguel Jose Oliveira
    Abstract:

    Abstract The widespread use of natural aggregates in construction activities, together with the global population increase, gave rise to a depletion of this natural resource and to progressive increase of its transport distances. On the other hand, the construction and demolition wastes (C&DW) resulting from the construction activities are often deposited in landfills and city outskirts, causing environmental and social problems, such as erosion, deforestation, water contamination and human conflicts. The reuse of C&DW in Concrete preparation would be a good solution for both problems. Recycled aggregates show, however, high water absorption due to porosity. At saturation, water flows from the inside to the engaging cement paste matrix and at dryness the opposite process occurs. This water flow breaks the aggregate-cement paste bonds and increases the W/C ratio in the interfacial transition zone, this degrades the fresh and hardened Concrete properties. In this work a staged mixing method based on the aggregate water absorption over time was developed. A staged mixing procedure was optimized to regulate the water flow and manufacture Concrete, using recycled aggregates, with levels of workability, strength and shrinkage equivalent to those of conventional Concrete. The physical, mechanical and geometrical properties of the aggregates were related to the properties of Concrete in its fresh and hardened state. Three types of commercial recycled aggregates were evaluated. Two types of natural aggregates were also studied for comparison purposes.

Lu Yang - One of the best experts on this subject based on the ideXlab platform.

  • photocatalyst efficiencies in Concrete Technology the effect of photocatalyst placement
    Applied Catalysis B-environmental, 2018
    Co-Authors: Lu Yang, Amer Hakki, Fazhou Wang, Donald E Macphee
    Abstract:

    Abstract The application of photocatalysts in Concrete Technology is by now a well-established concept. However, despite the great opportunities for air quality improvements to be derived from the considerable Concrete surfaces exposed to the atmosphere, particularly in cities where air quality is greatly affected by vehicle exhaust and industrial emissions, photocatalytic Concretes are still not in mainstream application. With current levels of NOx pollution considerably exceeding EU legislative guidelines in urban centres throughout the industrialised world, it is important to consider what the issues are. The likely barriers to more widespread implementation are likely to include cost effectiveness, which needs to be related to photocatalyst impact, but the challenges in measuring impact on air quality directly are complex. This paper seeks to place photocatalytic efficiencies into context, comparing performances of the conventional photocatalyst dispersion in surface mortar coatings with that of photocatalysts supported on surface exposed aggregates. The nature and impact of catalyst binding to the aggregate is also discussed.

Matthias Eckert - One of the best experts on this subject based on the ideXlab platform.

  • mitigation of the negative effects of recycled aggregate water absorption in Concrete Technology
    Construction and Building Materials, 2017
    Co-Authors: Matthias Eckert, Miguel Jose Oliveira
    Abstract:

    Abstract The widespread use of natural aggregates in construction activities, together with the global population increase, gave rise to a depletion of this natural resource and to progressive increase of its transport distances. On the other hand, the construction and demolition wastes (C&DW) resulting from the construction activities are often deposited in landfills and city outskirts, causing environmental and social problems, such as erosion, deforestation, water contamination and human conflicts. The reuse of C&DW in Concrete preparation would be a good solution for both problems. Recycled aggregates show, however, high water absorption due to porosity. At saturation, water flows from the inside to the engaging cement paste matrix and at dryness the opposite process occurs. This water flow breaks the aggregate-cement paste bonds and increases the W/C ratio in the interfacial transition zone, this degrades the fresh and hardened Concrete properties. In this work a staged mixing method based on the aggregate water absorption over time was developed. A staged mixing procedure was optimized to regulate the water flow and manufacture Concrete, using recycled aggregates, with levels of workability, strength and shrinkage equivalent to those of conventional Concrete. The physical, mechanical and geometrical properties of the aggregates were related to the properties of Concrete in its fresh and hardened state. Three types of commercial recycled aggregates were evaluated. Two types of natural aggregates were also studied for comparison purposes.

Gao Yu-feng - One of the best experts on this subject based on the ideXlab platform.

  • Discussion on prestressed Concrete Technology and its engineering application
    2020
    Co-Authors: Gao Yu-feng
    Abstract:

    From aspects of formwork, steel strand, Concrete pour, prestressed tension, grout injection the prefabrication of prestressed I shape beams is introduced. At last the development of prestressed Concrete Technology is made expectation.

  • Application of Prepacked Aggregate Concrete Technology in Gravity Wharf Reinforcement
    Applied Mechanics and Materials, 2012
    Co-Authors: Shu Min Li, Ting Guo Chen, Ke Wang, Gao Yu-feng
    Abstract:

    To improve the production capacity, a special area of the wharf’s working face is needed for production and shipment at the construction field of Offshore Oil Engineering (Qingdao, China) Co., Ltd. However, the load acted on the working face increases too much and the bearing capacity of the wharf structure is insufficient. In comprehensive consideration of the construction quantity, period and cost, and to make full use of the present structure, the prepacked aggregate Concrete Technology is applied to reinforce the rubble-mound foundation and the caissons. With significant improving of the load-carrying capacity, the wharf is available for the new production process. The practical application shows that the Technology can be applied to the reinforcement of the gravity wharf. And for very good effect and lots of advantages, it is worth to be widely applied.