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Admixtures
Published in Marios Soutsos, Peter Domone, Construction Materials, 2017
The major reason for entraining air is to provide freeze–thaw resistance to the concrete. Moist concrete contains free water in entrapped air and capillary voids, which expands on freezing, setting up disruptive internal bursting stresses. Successive freeze–thaw cycles, say, over a winter, may lead to a progressive deterioration. Entrained air voids, uniformly dispersed throughout the hcp, provide a reservoir for the water to expand into when it freezes, thus reducing the disruptive stresses. Entrained air volumes of only about 4%–7% by volume of the concrete are required to provide effective protection, but the bubble diameter and spacing are important factors. We will consider freeze–thaw damage in more detail when discussing durability of concrete in Chapter 24.
A method to assess climate change induced damage on flexible pavements with machine learning
Published in Andreas Loizos, Imad L. Al-Qadi, A. (Tom) Scarpas, Bearing Capacity of Roads, Railways and Airfields, 2017
Y. Qiao, Y. Zhang, M. Elshaer, J.S. Daniel
Temperature is a significant parameter for asphalt layer modulus and pavement deterioration e.g. rutting and roughness (Tighe, Smith et al. 2008, Mills, Tighe et al. 2009, Li, Mills et al. 2011, Qiao, Flintsch et al. 2013). An increase in temperature can reduce the moduli of asphalt layers and the reduction can be significant at extreme high temperatures (Monismith, Secor et al. 1965, Buttlar and Roque 1996). Increases in precipitation and groundwater level may increase the moisture content of unbound materials and subgrade. Resilient moduli of the unbound layers and subgrade can reduce significantly when the layers are exposed to high moisture content or become saturated (Hicks and Monismith 1971, Drumm, Reeves et al. 1997, Lekarp, Isacsson et al. 2000, Dawson 2009, Salour 2015). In cold climates, freeze-thaw can cause significant road damage when roads are open to traffic in the thawing period. In some regions, ordinary freeze-thaw cycles can be affected by climate change and, in a worst case, thawing period may be extended, inducing additional road damage.
Slope Stabilization
Published in R.P.C. Morgan, R.J. Rickson, Slope Stabilization and Erosion Control, 2003
Several types of flow landslides, including skin flows and solifluction, that occur on low angle slopes are attributed to high pore pressures during thaw (McRoberts and Morgenstern, 1974). As shown in equation 7. 9, the safety factor depends on the pore pressure parameter R, which in turn depends on the rate of thaw and rates of generation and dissipation of pore pressure. Natural organic cover, such as moss, serves as an insulating material that retards thaw and as a reinforcement that restrains movements in the thawed material. When the organic cover is destroyed, catastrophic movements can take place. Where the safety factor of a slope is inadequate, the stability can be improved by using a surcharge to increase the effective stress. Also, an insulating layer may be placed on the ground surface to reduce the rate of thaw. When an insulating layer is present, a numerical solution is used to obtain Fs and design charts have been presented by Pufahl and Morgenstern (1979). These may be used to compute the amount of insulation and surcharge required to produce an adequate safety factor. Peat may be used for insulation, although it may not be readily available in northern regions. Where synthetic insulation is used, vegetation grown on top of the surcharge contributes additional insulation, although its thermal properties are not well known.
Engineered water repellency for resilient and sustainable pavement systems
Published in International Journal of Geotechnical Engineering, 2023
M. Uduebor, J. Daniels, D. Adeyanju, Md Fyaz Sadiq, Bora Cetin
Moisture-related distress significantly contributes to the deterioration and damage of pavements (Akentuna et al. 2023; Camacho-Garita et al. 2019). The infiltration of moisture into pavement systems gradually weakens their strength and affects their durability under sustained traffic loading over time. This problem is further exacerbated in cold regions by frost heaving and thaw weakening, resulting in substantial damage to construction and transportation infrastructure, including pavements and granular roadways. Consequently, it leads to significant economic costs and safety hazards (Sadiq et al. 2023; Naqvi et al. 2022). According to (Koks et al. 2019), the global annual damages due to direct damage to road and railway assets range from 3.1 to 22 billion US dollars, with approximately 73% of these damages being moisture-related. The United States faces particularly high costs associated with road infrastructure damage and has a high demand for road maintenance, which has significant environmental implications. Road construction has a substantial carbon footprint, with the production of the hot mix asphalt (HMA) layer in pavements emitting 65.8 kg of CO2 per kilometre of road (Espinoza et al. 2019).
Multiscale model for predicting freeze-thaw damage in asphalt mixtures
Published in International Journal of Pavement Engineering, 2022
Lisa Lövqvist, Romain Balieu, Nicole Kringos
Infiltration of moisture into the asphalt mixture by diffusion may lead to emulsification of the binder close to the surface (Varveri et al.2015) as well as stripping at the mastic-aggregate interface (Kringos et al.2008b). Additionally, in more open asphalt structures, the moisture might erode the asphalt as it flows through the air void system (Kringos et al.2008b). These mechanisms all cause a deterioration of material and structural properties that increase the risk of freeze-thaw damage, which occurs as the moisture trapped inside the air voids expands as it freezes to ice. The cyclic pressure inside the material caused by the freeze-thaw cycle may also lead to damage in the form of erosion, micro-cracks and chemo-mechanically induced deterioration of the material properties, eventually leading to an increase in volumetric pore volume in the mixture (Xu et al.2015). This effectively leads to an overall decrease of different properties of the mixture, such as its strength and stiffness (Feng et al.2010, Si et al.2014, Luo et al.2017, Pan et al.2017).
Freeze–thaw and thermal cycle durability of pervious concrete with different aggregate sizes and water–cement ratios
Published in International Journal of Pavement Engineering, 2021
Yan Tan, Chenxu Zhou, Chuheng Zhong, Jinzhi Zhou
The frost resistance and strength of PC are equally important. Indeed, damage to cemented materials is one of the primary forms of damage caused by freeze–thaw. Powers first studied the basic mechanism of such frost damage in cement-based materials (Powers 1945). It is reported that in PC prepared by partially replacing cement with waste glass powder, the increase in the amount of waste glass powder can improve the frost resistance of PC (Li et al. 2021a). Surface modification of recycled aggregate can increase both the compressive strength and the freeze–thaw durability of recycled aggregate PC more effectively than integral modification of cement matrix can (Zou et al. 2021). The effect of PC featuring different aggregate sizes, porosities and water-binder ratios on Porosity, permeability, compressive strength, flexural strength and freeze–thaw resistance has also been extensively investigated (Kevern et al. 2010, Liu et al. 2018, Liu et al. 2019). fibre, rubber, SBR latex, air entraining agent and other admixtures found to affect the strength and frost resistance of PC (Singh and Murugan n.d., Gesoglu et al.2014, Kevern et al. 2015, Wu et al. 2016, Tabatabaeian et al. 2019, Bilal et al. 2021). Addition of a small amount of fine sand to PC improves its strength and freezing–thawing resistance while maintaining adequate water permeability (Wang et al. 2021). At the same time, Taheri et al. (2021) proposed a new test method for evaluating the freeze–thaw durability of PC. In addition, in winter, following significant snowfall, large quantities of water enter concrete after temperatures rise (Backstrom 2000). In winter, when temperatures are often below freezing, the volume of water in PC increases. Freeze–thaw can cause internal stresses that could eventually result in deterioration of PC over repeated freeze–thaw cycles. Accordingly, the frost resistance of PC is the focus that scholars still need to study in the future.