China
Africa
Explore chapters and articles related to this topic
Study on permeability performance decay law and clogging test of porous asphalt mixture
Published in Xianhua Chen, Jun Yang, Markus Oeser, Haopeng Wang, Functional Pavements, 2020
Haoran Zhu, Mingming Yu, Shaochan Duan*
In recent years, road researchers have studied the drainage and anti-clogging properties of porous asphalt mixtures. Moriyoshi et al. (Moriyoshi et al., 2013) reported the permeability coefficient of porous asphalt pavement which gradually decreases after opening the traffic. Coleri et al. (Coleri et al., 2013) found that the decrease of the permeability coefficient of porous asphalt pavement had a clear correlation with the attenuation of the pore structure. Tan et al. (Tan et al., 2000) showed that the permeability coefficient of porous asphalt pavement had a quadratic function relationship with the mass of particles inside the specimen. Hamzah et al. (Othman, 2005) studied the anti-clogging performance of single-layer and double-layer drainage asphalt pavement by loading the suspension.
Durability Problems in Concrete
Published in Satish Chandra, Yoshihiko Ohama, in Concrete, 2020
Olofsson and Thalenius14 investigated some bridges in Sweden. During their investigation, efflorescence on concrete surface was generally observed, and in a few cases, surface cracks were also noted along with big surface pores (Figure 3.3). These surface pores might have been the result of bad workmanship. The pores could have been instrumental in causing early deterioration of the concrete as they help water and salt solutions to penetrate the concrete. This would have caused dissolution leading to leaching and crack formation due to the crystallization of salts that might form because of the interaction of penetrating solution and the cement hydration products. Such deterioration causes the concrete to lose strength due to the leaching, losing of the binder, salt crystallization, and crack formation. Further, with the consumption of alkalies, the concrete loses its neutralization capacity, and this causes reinforcement corrosion, leading to spalling and cracking of the concrete.
2 Conversion with SOCs 5
Published in Yun Zheng, Bo Yu, Jianchen Wang, Jiujun Zhang, Carbon Dioxide Reduction through Advanced Conversion and Utilization Technologies, 2019
Yun Zheng, Bo Yu, Jianchen Wang, Jiujun Zhang
Additives can modify suspension viscosity and interaction among particles. The pore structures can be controlled by introducing various additives. Glycerol, polyacrylic acid, and polyvinyl alcohol (PVA) are common additives in aqueous systems.96,128 Among them, glycerol has many advantages, such as a low freezing point, no toxicity, and low cost; thus, it is the most frequently used additive.164–166 Because glycerol has polar groups, water molecules are the easiest to concentrate around them to form hydrogen bonds. When adding glycerol, the viscosity will be enhanced effectively and the diffusion of the solvent is limited, which generates smaller ice crystals.167,168 Some bridge structures among the ceramic walls are generated by adding glycerol.
Mechanical and Structural Investigation of Traditional Masonry Systems with Diverse Types of Bricks and Hydrated Lime Mortars
Published in International Journal of Architectural Heritage, 2023
Gayoon Lee, Jun Hyoung Park, Chan Hee Lee, Sung-Min Lee, Kihak Lee
Figure 14 illustrates the mercury intrusion incremental curves for the two types of bricks with different pore size distributions. The volume of pores at each pore diameter was measured using mercury intrusion porosimetry, and the distribution characteristics of the different pores were confirmed. The factory-made brick showed numerous rather large voids when observed with the naked eye and a stereomicroscope, but the small voids on the actual surface were found to be significantly smaller than those of the hand-made bricks. The majority of pores on the factory-made brick surface had a diameter of 2 µm, and the average pore diameter was calculated to be 0.4 µm. On the other hand, pores of various sizes were scattered in the hand-made brick, and the average pore diameter increased to 657.90 nm. There were a few pores of various sizes on the surface of the hand-made bricks, unlike the observation made with the unaided eye and stereomicroscope.
Influence of freeze–thaw cycles on apparent dynamic tensile strength, apparent dynamic fracture toughness and microstructure of concrete under impact loading
Published in European Journal of Environmental and Civil Engineering, 2021
Pore size distribution is the ratio between the pore volumes of different sizes and the total pore volumes. In order to classify the pore sizes better and obtain a more accurate pore size distribution associated with F–T cycles, the pore size distribution was divided into three groups: capillary pores (<50 nm), mesopores (50–200 nm) and macropores (>200 nm), and the pore size classification is presented in Figure 12. It can be seen from the figure that the capillary pores account for the dominant scope of intact specimens without suffering F–T cycles. When the number of cycles increased to 50, the proportion of mesopores and macropores increased slightly while capillary pores decreased. The results also indicated that there is an obvious decrease in the mechanical properties of concrete specimens under the circumstance. With the increase of F–T cycles, the proportion of capillary pores continued to decrease sharply and the number of mesopores and macropores continued to increase, with microstructures getting impaired and mechanical properties deteriorating in the procedure.
Quantification of porosity in composite resins delivered by injectable syringes using X-ray microtomography
Published in Biomaterial Investigations in Dentistry, 2020
Bo Wold Nilsen, Mathieu Mouhat, Asbjørn Jokstad
A pore is a space-occupying area within or at the border of material and the amount of porosity describes the volume percentage of pores per volume unit (vol%). From a mechanical perspective, pores represent defects/flaws in material as it is a discontinued phase of the material with an e-modulus of zero [3]. There is no direct clinical evidence on how the amount of porosity may affect the clinical performance of CPR restorations. Still, ample data from in vitro studies indicate that restoration with embedded pores may be a clinical concern. An increase in the amount of porosity in the range of 1.5–3 vol% in a CPR reduces the compressive strength and compressive fatigue limit, estimated to be in the range of 30–50% [4], and the pores may be considered as critical defects associated with fracturing of specimens [5].