Using precast concrete pipes to develop sewage water transportation systems is important for keeping hygienic, safe, and sustainable urban environments. This study reviews the state-of-the-art knowledge of the manufacturing processes, materials, curing regimes, design philosophies, laboratory and field tests, and various standards for assessing the quality of precast concrete pipes. Data from various sources such as research publications, technical reports, dissertations, and standards code provisions were gathered and presented in tabular/ graphical form to analyze the critical factors that affect concrete pipe behavior. The manufacturing process was found to be an important factor that affects the quality of precast concrete pipes. A review of past failures of pipes showed that cracking, deterioration of concrete, and erosion or voids in concrete pipes were due to biogenic sulfuric acid attack. A comparison of the indirect design and direct design methods for precast concrete pipes was conducted, proving the advantages of the direct design method over the century-old indirect design method. Closed-form equations were presented for the complete distribution of internal forces, i.e., bending moments, shear forces, and thrust forces over the circumference of the pipe. Various challenges including the development of laboratory and field quality assessment tests, and a widely accepted standard of precast concrete pipes were also highlighted. Despite its importance, the field performance of precast concrete pipes was explored in a dearth of previous studies due to its costly procedures. Therefore, long-term monitoring of buried concrete pipes is needed to enhance the understanding of their complex behavior, accounting for the changing soil-pipe interaction, erosion of soil, and deterioration of concrete and steel over time. This study should assist infrastructure stakeholders and operation managers in making informed decisions regarding the choice of materials, design methods, manufacturing, and curing techniques to overcome catastrophic pipe failures and incidents, leading to a safe and sustainable environment and mitigating financial losses due to pipe failures.

To investigate the effect of combined end-and-shaft post-grouting on the vertical load-bearing performance of bridge-bored piles in the Dongting Lake area of Hunan, two post-grouted piles were subjected to bi-directional O-cell and top-down load tests before and after combined end-and-shaft grouting, based on the Wushi to Yiyang Expressway project. A comparative analysis was conducted on the bearing capacity, deformation characteristics, and load transfer behavior of the piles before and after grouting. This study also examined the conversion coefficient gamma values of different soil layers obtained from the bi-directional O-cell test for bearing capacity calculations. Additionally, the characteristic values of the end bearing capacity, obtained from the bi-directional O-cell and top-down load tests, were compared with the values calculated using the relevant formulas in the current standards, which validated the accuracy of existing regulations and traditional loading methods. The results indicate that the stress distribution along the pile shaft differed between the two test methods. In the bi-directional O-cell test, the side resistance developed from the end to the head, while in the top-down load test, it developed from the head to the end. After combined post-grouting, the ultimate bearing capacity of the piles significantly increased, with side resistance increasing by up to 81.03% and end resistance by up to 105.66%. The conversion coefficients for the side resistance in silty sand and gravel before and after grouting are 0.86 and 0.80 and 0.81 and 0.69, respectively. The characteristic values of the end bearing capacity, as measured by the bi-directional O-cell and top-down load tests, were substantially higher than those calculated using the current highway bridge and culvert standards, showing increases of 133.63% and 86.15%, respectively. These findings suggest that the current standard formulas are overly conservative. Additionally, the measured values from the top-down load test may underestimate the actual bearing capacity of piles in engineering projects. Therefore, it is recommended that future pile foundation designs incorporate both bi-directional O-cell testing and combined post-grouting techniques to optimize design solutions.

Decades of extensive and exponentially growing production and use of conventional plastics have led to the accumulation of plastic waste in the environment, contributing to the anthropocene pressure on ecosystems. Bioplastics (defined as bio-based and/or biodegradable plastics) have been promoted as a more sustainable alternative and substitute for conventional plastics. Nonetheless, the literature contains numerous conflicting conclusions regarding their suitability and environmental implications. One central point of contention concerns their biodegradability and the conditions necessary for proper degradation. In real-world settings, like anaerobic digestion plants or marine environments, biodegradable plastics may not degrade as rapidly or efficiently as suggested by laboratory tests. A systematic literature review was conducted to explore the current level of knowledge regarding the environmental fate and consequences of biodegradable plastics, thereby substantiating discussions on their future role in society. The review covered the degradation of biodegradable plastics in waste management environments (e.g., compost, sludge, or landfill) and the open environment (e.g., seawater, freshwater, or soil). As clearly highlighted by this review, comparisons and quantitative analysis of data on plastic degradation are challenged by significant methodological variations, encompassing differences in testing methods, test materials, and quantification strategies. Moreover, the review revealed several research gaps, highlighting, in particular, the need to i) intensify the research on polyhydroxyalkanoates (PHAs), polybutylene adipate terephthalate (PBAT), and polybutylene succinate (PBS) to match the level of polylactic acid (PLA) and starch-based plastics, ii) develop standard test methods in field conditions, and iii) couple degradation testing with ecotoxicological tests. The overview established in this review is essential for a more thorough evaluation of the environmental performance of biodegradable plastics. Furthermore, the findings of this study contribute to supporting the responsible future production and use of biodegradable plastics in various products, including assessing their role as alternatives to conventional plastics.

Due to sparse data and discontinuous time observations in the circum-Arctic region, freezing index and thawing index, as useful indicators, are widely used in permafrost distribution, climate changes and cold-region engineering analysis. However, previous researches on freezing/thawing index over this region were estimated based on mean monthly air temperature. In this paper, we analyzed the spatial and temporal variations of the freezing/thawing index over the circum-Arctic from 1901 to 2015 based on the daily datasets, besides monthly datasets. The results showed that freezing index had a downward changing trend and thawing index had an upward trend during 1901-2015. More important, the change trend in freezing/thawing index after 1988 was more significant than before. Furthermore, different freezing/thawing index based on daily datasets and the monthly datasets were assessed and compared according to daily data from 17 meteorological stations, comprehensive relative errors evaluation implied that freezing/thawing based on daily datasets was more accurate generally, although both of other datasets were available in calculating the freezing/thawing index. As the daily datasets are better in calculating annual freezing/thawing index, therefore, the permafrost extent was estimated by a climate-based predictive model combined with snow depth data from Canadian Meteorological Centre (CMC). Finally, considering that the published permafrost map of the circum-Arctic only shows the past permafrost distribution, but it cannot reflect the permafrost distribution after 2000 under the climate warming. Hence, we simulated the current (mean from 2000 to 2015) permafrost area which is 19.96 x 10(6) km(2), and the results showed some discrepancies between published and simulated permafrost extent mainly located in isolated permafrost regions. (c) 2019 Elsevier B.V. All rights reserved.