scholarly journals Evaluating the potential of freeze-thaw damage in internally insulated masonry under climate change using different models

2019 ◽  
Vol 282 ◽  
pp. 02081
Author(s):  
Sahar Sahyoun ◽  
Hua Ge ◽  
Maurice Defo ◽  
Michael Lacasse
Keyword(s):  
Climate Change ◽  
Frost Damage ◽  
Freezing And Thawing ◽  
Damage Functions ◽  
Building Envelopes ◽  
Freeze Thaw ◽  
Changing Climate ◽  
Thaw Period ◽  
Damage Risk ◽  
Good Agreement

To mitigate the effects of climate change, higher insulation levels in buildings are mandated by the National Energy Code for Buildings. However, increased insulation levels within building envelopes may lead to a greater risk of moisture problems. With a changing climate, higher rainfall intensity, stronger winds and more storms are expected, which may increase wind-driven rain loads on façade and risks for rain penetration damages of building envelopes. This paper aims to present results of the effects of climate change on the freeze-thaw damage risk of internally insulated brick masonry walls of buildings in different Canadian cities, using different freeze-thaw models. Freeze-thaw damage was evaluated using different freeze-thaw models. Simulations were performed using DELPHIN 5.9.4. Results showed potential risk to freeze-thaw in Montreal and Vancouver after retrofit. Under climate change, Winnipeg has the lowest risk to frost damage, though damage functions showed an increase in the level of severity. Comparing the results of different models under a changing climate, the damage functions seemed in a good agreement for most of the cases, except for the Indicative Freeze-Thaw Cycles (IFTC) evaluated in St-Johns. This model counts the number of freeze-thaw cycles based on short duration of freezing and thawing and therefore does not consider longer freeze-thaw period.

scholarly journals Effects of Cyclic Freeze–Thaw on the Steel Bar Reinforced New-To-Old Concrete Interface

Molecules ◽  
2020 ◽  
Vol 25 (5) ◽  
pp. 1251
Author(s):  
Tao Luo ◽  
Chi Zhang ◽  
Xiangtian Xu ◽  
Yanjun Shen ◽  
Hailiang Jia ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Shear Strength ◽  
Concrete Structures ◽  
Freezing Temperature ◽  
Frost Damage ◽  
Freezing And Thawing ◽  
Shear Properties ◽  
Freeze Thaw ◽  
Steel Bar ◽  
Concrete Interface

Frost damage of concrete has significant effects on the safety and durability of concrete structures in cold regions, and the concrete structures after repair and reinforcement are still threatened by cyclic freezing and thawing. In this study, the new-to-old concrete interface was reinforced by steel bar. The shear strength of the new-to-old concrete interface was tested after the new-to-old combination was subjected to cyclic freeze–thaw. The effects of the diameter of the steel bar, the compressive strength of new concrete, the number of freeze–thaw cycles and the freezing temperatures on the shear properties of new-to-old concrete interface were studied. The results showed that, in a certain range, the shear strength of the interface was proportional to the diameter of the steel bar and the strength of the new concrete. Meanwhile, the shear strength of the reinforced interface decreased with the decreasing of the freezing temperature and the increasing of the number of freeze–thaw cycles.

Climate change in other taxa and links to bird studies

2019 ◽  
pp. 257-264
Author(s):  
David W. Inouye
Keyword(s):  
Climate Change ◽  
Frost Damage ◽  
Ecological Communities ◽  
Case Histories ◽  
Changing Climate ◽  
Wide Range

Phenological responses to climate change are the most commonly measured responses of plants and animals to climate change, and most studies show that species are advancing the timing of their seasonal activities in response to warming temperatures. Birds interact with a wide range of other species, playing roles as herbivores, predators, prey, and disease hosts. Because the species they interact with are all likely changing phenology and distribution in response to the changing climate, but often at different rates, mismatches with historical patterns are affecting ecological communities in a variety of ways. Unexpected phenomena such as increases in frost damage, and less surprising ones such as developing phenological mismatches between migratory and sedentary species, are discussed as case histories illustrating these changes.

Analysis of Freeze-Thaw Damage of Lightweight Aggregate Concrete

2009 ◽  
Vol 417-418 ◽  
pp. 829-832
Author(s):  
Ji Ze Mao ◽  
Koichi Ayuta ◽  
Hui Qi ◽  
Zong Min Liu
Keyword(s):  
Water Content ◽  
Coarse Aggregate ◽  
Lightweight Aggregate ◽  
Frost Damage ◽  
Lightweight Aggregate Concrete ◽  
Freezing And Thawing ◽  
Aggregate Concrete ◽  
Freeze Thaw ◽  
Expansion Pressure ◽  
Micro Cracks

Since lightweight aggregate usually accounts for a higher percentage of the concrete by volume, the properties of lightweight aggregate can significantly influence the properties of the resulting concrete. In this study, we investigated the effects of the water content of lightweight coarse aggregate (LCA) on freeze-thaw resistance of lightweight aggregate concrete (LC) and analyzed how to control the fatal frost damage - cracks in LC. The results showed that the freeze-thaw resistance of LC was determined by the water content of LCA. It is clear that lowering the water content of LCA below 17% is the key method to secure the freeze-thaw resistance of LC. The study showed that the higher the water content of LCA, the higher the weight loss and the larger pore volume of LCA, the bigger the length expansion and the lower the durability factors of LC after freezing and thawing. Internal cracks occurred only in the concrete specimens that contained LCAs with higher water content when subjected to freezing and thawing. Expansion pressure occurred easily in the higher water content LCAs and micro-cracks formed initially in the weak grains. Then micro-cracks enlarged and spread to the mortar as the number of freeze-thaw cycles increased. This process eventually caused LC expansion and damage.

scholarly journals Investigation of thermal, moisture, and mechanical properties of wet and dry fired clay materials to assess frost damage risk

2019 ◽  
Vol 282 ◽  
pp. 02083
Author(s):  
Kazuma Fukui ◽  
Chiemi Iba ◽  
Madoka Taniguchi ◽  
Kouichi Takahashi ◽  
Daisuke Ogura
Keyword(s):  
Mechanical Properties ◽  
Environmental Conditions ◽  
Frost Resistance ◽  
Building Materials ◽  
Frost Damage ◽  
Thermal And Mechanical Properties ◽  
Freeze Thaw ◽  
Different Temperatures ◽  
Damage Risk ◽  
Clay Materials

Frost action is one of the main causes for deterioration of porous building materials under defined hygrothermal conditions. For an accurate assessment of the frost damage risk under various environmental conditions, thermal, moisture, and mechanical properties should be considered; the hygrothermal properties affect the distribution of temperature and amount of frozen water in the material, whereas the mechanical properties are necessary to predict deformation and damage. Moreover, the dependency of these properties on the moisture content should be understood. Therefore, in this study, thermal, moisture, and mechanical properties of wet and dry fired clay materials were measured. The fired clay materials were sintered at two different temperatures, 1000 °C and 1100 °C (samples T10 and T11, respectively) for comparison. The measured thermal and mechanical properties are considerably different in the wet state compared to the dry state. Freeze–thaw tests were conducted to investigate the relation between the material properties and the frost resistance under a simple experimental condition. As expected, based on the pore structure and obtained mechanical properties, T10 exhibited lower frost resistance than T11 in the freeze–thaw test. Finally, frost damage risk was assessed under various environmental conditions based on the obtained hygrothermal and mechanical properties.

Climate-induced treeline mortality during the termination of the Little Ice Age in the Greater Yellowstone Ecoregion, USA

The Holocene ◽  
2021 ◽  
pp. 095968362110116
Author(s):  
Maegen L Rochner ◽  
Karen J Heeter ◽  
Grant L Harley ◽  
Matthew F Bekker ◽  
Sally P Horn
Keyword(s):  
Climate Change ◽  
Tree Ring ◽  
Little Ice Age ◽  
Climate Changes ◽  
Frost Damage ◽  
Ice Age ◽  
Spatial And Temporal Variability ◽  
Whitebark Pine ◽  
Engelmann Spruce ◽  
Greater Yellowstone

Paleoclimate reconstructions for the western US show spatial variability in the timing, duration, and magnitude of climate changes within the Medieval Climate Anomaly (MCA, ca. 900–1350 CE) and Little Ice Age (LIA, ca. 1350–1850 CE), indicating that additional data are needed to more completely characterize late-Holocene climate change in the region. Here, we use dendrochronology to investigate how climate changes during the MCA and LIA affected a treeline, whitebark pine ( Pinus albicaulis Engelm.) ecosystem in the Greater Yellowstone Ecoregion (GYE). We present two new millennial-length tree-ring chronologies and multiple lines of tree-ring evidence from living and remnant whitebark pine and Engelmann spruce ( Picea engelmannii Parry ex. Engelm.) trees, including patterns of establishment and mortality; changes in tree growth; frost rings; and blue-intensity-based, reconstructed summer temperatures, to highlight the terminus of the LIA as one of the coldest periods of the last millennium for the GYE. Patterns of tree establishment and mortality indicate conditions favorable to recruitment during the latter half of the MCA and climate-induced mortality of trees during the middle-to-late LIA. These patterns correspond with decreased growth, frost damage, and reconstructed cooler temperature anomalies for the 1800–1850 CE period. Results provide important insight into how past climate change affected important GYE ecosystems and highlight the value of using multiple lines of proxy evidence, along with climate reconstructions of high spatial resolution, to better describe spatial and temporal variability in MCA and LIA climate and the ecological influence of climate change.

scholarly journals Introducing the Built Environment in a Changing Climate: Interactions, Challenges, and Perspectives

Climate ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 104
Author(s):  
Giulia Ulpiani ◽  
Michele Zinzi
Keyword(s):  
Climate Change ◽  
Built Environment ◽  
Climate Change Adaptation ◽  
Changing Climate ◽  
Climate Interactions

Planning for climate change adaptation is among the most complex challenges cities are facing today [...]

scholarly journals Strength and Microscopic Damage Mechanism of Yellow Sandstone with Holes under Freezing and Thawing

2020 ◽  
Vol 2020 ◽  
pp. 1-13 ◽  
Author(s):  
Huren Rong ◽  
Jingyu Gu ◽  
Miren Rong ◽  
Hong Liu ◽  
Jiayao Zhang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Pore Size ◽  
Power Function ◽  
Damage Mechanism ◽  
Uniaxial Compression Test ◽  
Freezing And Thawing ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Microscopic Damage

In order to study the damage characteristics of the yellow sandstone containing pores under the freeze-thaw cycle, the uniaxial compression test of saturated water-stained yellow sandstones with different freeze-thaw cycles was carried out by rock servo press, the microstructure was qualitatively analyzed by Zeiss 508 stereo microscope, and the microdamage mechanism was quantitatively studied by using specific surface area and pore size analyzer. The mechanism of weakening mechanical properties of single-hole yellow sandstone was expounded from the perspective of microstructure. The results show the following. (1) The number of freeze-thaw cycles and single-pore diameter have significant effects on the strength and elastic modulus of the yellow sandstone; the more the freeze-thaw cycles and the larger the pore size, the lower the strength of the yellow sandstone. (2) The damage modes of the yellow sandstone containing pores under the freeze-thaw cycle are divided into five types, and the yellow sandstone with pores is divided into two areas: the periphery of the hole and the distance from the hole; as the number of freeze-thaw cycles increases, different regions show different microscopic damage patterns. (3) The damage degree of yellow sandstone is different with freeze-thaw cycle and pore size. Freeze-thaw not only affects the mechanical properties of yellow sandstone but also accelerates the damage process of pores. (4) The damage of the yellow sandstone by freeze-thaw is logarithmic function, and the damage of the yellow sandstone is a power function. The damage equation of the yellow sandstone with pores under the freezing and thawing is a log-power function nonlinear change law and presents a good correlation.

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