Search Results (10)

The pursuit of sustainable alternatives to portland cement has become a global imperative within the construction sector, driven by the need to reduce carbon dioxide emissions and energy consumption. Among the promising alternatives, agricultural ashes have garnered attention for their potential as alternative supplementary cementitious materials (ASCMs), owing to their inherent pozzolanic properties when appropriately processed. However, the availability and utilization of these ashes have predominantly been concentrated in tropical and subtropical regions, where such biomass is more abundant. This review offers a comprehensive bibliometric analysis to identify and assess agricultural ashes (specifically switchgrass, barley, sunflower, and oat husks) that are cultivated in temperate and cold climates and exhibit potential for SCM application. The analysis aims to bridge the knowledge gap by systematically mapping the existing research landscape and highlighting underexplored resources suitable for cold-region implementation. Key processing parameters, including incineration temperature, retention duration, and post-combustion grinding techniques, are critically examined for their influence on the resulting ash’s physicochemical characteristics and pozzolanic reactivity. In addition, the effect on fresh, hardened, and durability properties was evaluated. Findings reveal that several crops grown in colder regions may produce ashes rich in reactive silica, thereby qualifying them as viable ASCM candidates and bioenergy sources. Notably, the ashes derived from switchgrass, barley, oats, and sunflowers demonstrate significant reactive silica content, reinforcing their potential in sustainable construction practices. Hence, this study underscores the multifaceted benefits of contributing to the decarbonization of the cement industry and circular economy, while addressing environmental challenges associated with biomass waste disposal and uncontrolled open-air combustion. Full article

In aging residential neighborhoods, insufficient public spaces and a weakened sense of belonging have led to declining community vitality. Addressing the widespread idleness of boiler room facilities in cold-region contexts, this study integrates GPS tracking, Wi-Fi probe detection, questionnaire surveys, and field observations to develop a three-dimensional “space–time–behavior” evaluation model comprising five core indicators: activity type, spatial range, duration, frequency, and volatility. Unlike prior studies that rely on single data sources or unidimensional metrics, our multi-source approach enhances spatiotemporal resolution, improves the accuracy of subjective perceptions, and enables cross-validation between objective behavioral trajectories and residents’ self-reports, thereby significantly strengthening the comprehensiveness and reliability of community vitality measurement. The results show that the community service center conversion model maximizes spatial efficiency through functional integration, achieving a vitality score of 3.64—substantially higher than those for recreational renovations (3.16) and non-renovated sites (2.67). This model increases space utilization by 2.2-fold, sustains 12 h daily vitality, reduces residents’ activity radii by 38%, and boosts intergenerational interaction frequency by 43%, effectively bridging age group divides. We identify a “functional hybridization–spatial permeability–usage sustainability” mechanism underlying renovation efficacy and recommend the community service center paradigm as a priority strategy. The quantitative decision support framework established here offers empirical guidance for renewing existing spaces in severe climatic environments. Full article

Transportation infrastructure such as concrete pavements, parapets, barriers, and bridge decks in cold regions are usually exposed to a heavy amount of deicing chemicals during the winter for ice and snow control. Various deicer salts can physically and chemically react with concrete and result in damage and deterioration. Currently, Idaho uses four different types of deicers during the winter: salt brine, mag bud converse, freeze guard plus, and mag chloride. The most often utilized substance is salt brine, which is created by dissolving rock salt at a concentration of 23.3%. Eight concrete mixtures for paving and structural purposes were made and put through a battery of durability tests. Following batching, measurements were made of the unit weight, entrained air, slump, and super air meter (SAM) fresh characteristics. Rapid freeze–thaw (F-T) cycle experiments, deicing scaling tests, and surface electrical resistivity testing were used to test and assess all mixes. Tests with mag bud converse, freeze guard plus mag chloride, and acid-soluble chloride were conducted following an extended period of soaking in salt brine. Two different structural mixtures were suggested as a result of the severe scaling observed in the structural mixtures lacking supplemental cementitious materials (SCMs) and the moderate scaling observed in the other combinations. The correlated values of the SAM number with the spacing factor have been shown that mixture with no SCMs has a spacing factor of 0.24, which is higher than the recommended value of 0.2 and concentrations of acid soluble chloride over the threshold limit were discernible. In addition, the highest weight of calcium hydroxide using the TGA test was observed. For all examined mixes, the residual elastic moduli after 300 cycles varied between 76.0 and 83.3 percent of the initial moduli. Mixture M5 displayed the lowest percentage of initial E (76.0 percent), while mixtures M1 and M2 showed the highest percentage of residual E (83.3 and 80.0 percent, respectively) among the evaluated combinations. There were no significant variations in the percentage of maintained stiffness between the combinations. As a result, it was difficult to identify distinct patterns about how the air content or SAM number affected the mixture’s durability. Class C coal fly ash and silica fume were present in the suggested mixtures, which were assessed using the same testing matrix as the original mixtures. Because of their exceptional durability against large concentrations of chemical deicers, the main findings suggest altering the concrete compositions to incorporate SCMs in a ternary form. Full article

With the rising demand for sustainable infrastructure, addressing the limitations of Ordinary Portland Cement (OPC) is crucial, particularly for exposed structures such as pavements and bridge decks. Portland limestone cement (PLC) is a sustainable alternative that delivers environmental benefits and comparable performance. This study used a systematic review and meta-analysis with a random-effects model to evaluate PLC’s strength development, durability, and sustainability. The findings indicate that PLC generally matches or surpasses OPC in terms of compressive strength, freeze–thaw resistance, and sulfate durability. However, its setting time and early-age cracking require further optimization, especially in cold climates. Additionally, this study highlights the fire performance advantages of PLC and its enhanced chloride resistance. The analysis identified critical research gaps, including long-term field performance and regional adaptation to extreme environmental conditions. These findings contribute to a deeper understanding of PLC’s role in sustainable construction and offer future research directions on hybrid cements and admixture compatibility. Full article

Given the increasing demand for higher construction productivity and better thermal resistance, adopting innovative building envelope systems is crucial. Dry-stack masonry blocks have emerged as a viable solution, due to their rapid assembly, mortar-free construction, and reduced dependence on skilled labor. However, there is a lack of scientific evaluation on the thermal performance of dry-stack blocks for cold climate zones and corresponding proper designs. This study addresses this gap by investigating market-available blocks and proposing two innovative block designs—a composite block and a simple block—highlighting their thermal performance and associated challenges. Using finite element modelling, the thermal resistance of these blocks was carefully assessed and compared. The results show that thermal bridging, induced by masonry ties penetrating the insulation, significantly impacts the thermal resistance of the wall made with simple blocks, resulting in an 11% decrease in the effective thermal resistance (R-value) as compared to the composite block walls. Furthermore, compared to a conventional masonry wall with the same insulation thickness, the composite-block wall exhibits a 24% higher R-value. The composite block outperforms existing market options in terms of thermal resistance, making it a superior choice for cold climate regions. Conversely, the simple block is preferred when sophisticated manufacturing facilities are unavailable. Overall, the composite block wall’s improved thermal resistance can make a meaningful contribution to lowering operational energy demand (i.e., operational carbon), contributing to the shift to a sustainable building stock. Full article

In the cold regions of China, the existing rural houses are widely distributed and in large numbers. There are widespread problems such as low thermal performance of building envelopes, high building energy consumption, and poor indoor thermal environments. Reducing the energy consumption of building heating by reforming the envelope structure can reduce the environmental pollution caused by heating. In this paper, the existing rural houses in Tongchuan City, Shaanxi Province are taken as the research object, and EnergyPlus software is used to calculate building heating energy consumption, and the schemes are compared and selected via the entropy value method. Based on a comprehensive benefit evaluation, the best scheme for the renovation of building envelopes of rural houses in Tongchuan City is put forward. The research results show that the energy saving rate of buildings can reach more than 50% after renovation. In the evaluation of energy saving, incremental cost, return on investment, carbon emission reduction and unguaranteed hours, the weights are 0.1915, 0.2104, 0.2312, 1755, and 0.187, respectively. The best renovation scheme for rural housing is as follows: the thickness of the XPS board is 90 mm for exterior wall insulation; the thickness of the XPS board is 80 mm for roof insulation; the window-to-wall ratio of additional sunspace is 0.6; and the type of exterior windows is a broken-bridge hollow aluminum window of 6 + 12A + 6 (mm). Full article

Accurate retrieval of ice surface temperature (IST) over the Arctic ice-water mixture zone (IWMZ) is significantly essential for monitoring the change of the polar sea ice environment. Previous researchers have focused on evaluating the accuracy of IST retrieval in pack ice regions, possibly on account of the availability of in situ measurement data. Few of them have assessed the accuracy of IST retrieval on IWMZ. This study utilized Landsat 8/TIRS and Operation IceBridge observations (OIB) to evaluate the accuracy of the current IST retrieval method in IWMZ and proposed an adjustment method for improving the overall accuracy. An initial comparison shows that Landsat 8 IST and OIB IST have minor differences in the pack ice region with RMSE of 0.475 K, MAE of 0.370 K and cold bias of −0.256 K. In the thin ice region, however, the differences are more significant, with RMSE of 0.952 K, MAE of 0.776 K and warm bias of 0.703 K. We suggest that this phenomenon is because the current ice-water classification method misclassified thin ice as water. To address this issue, an adjusted method is proposed to refine the classification of features within the IWMZ and thus improve the accuracy of IST retrieval using Landsat 8 imagery. The results demonstrate that the accuracy of the retrieved IST in the two cases was improved in the thin ice region, with RMSE decreasing by about 0.146 K, Bias decreasing by about 0.311 K, and MAE decreasing by about 0.129 K. After the adjustment, high accuracy was achieved for both pack ice and thin ice in IWMZ. Full article

The fatigue safety of cable-girder anchorage structures in cable-stayed bridges under long-term service has attracted much attention. For bridges located in seasonally cold regions, the effect of low-temperature environments should be considered when evaluating fatigue performance. Using the Heilongjiang Bridge in China as a case study, a room-temperature fatigue test with a numerical simulation that considers the low-temperature effect on both load effect and fatigue resistance was proposed. A fatigue test with increased testing load amplitude was performed on a 1:3.75 ratio specimen. After 3.2 million loading cycles and using an acoustic emission technique, no fatigue crack was observed in the anchorage structure. The extended finite element method was then adopted to analyze the anchorage zone’s fatigue crack initiation position and propagation path. Finally, based on the fatigue characteristics of bridge steel, the fatigue resistance to the crack propagation of the vulnerable area was evaluated under three different service conditions. The results show that the fatigue performance of the anchorage zone at low temperatures is sufficient. Moreover, this paper provides a more widely applicable and cost-effective approach for the fatigue evaluation of steel bridges. Full article

With the worldwide dissemination of the “green development” concept and the advancement of China’s new rural construction, the sustainable development of rural residences has gained significant attention within the construction industry. This article focuses on large-scale prefabricated insulation block houses used in China’s cold regions, specifically examining the case of Defa Village in Nenjiang City, Heilongjiang Province. By utilizing thermal imaging cameras, the thermal bridge parts of these houses are detected, and a finite element model is established to optimize the comprehensive heat transfer coefficient of these areas. This optimization is achieved by expanding the insulation layer and implementing low thermal bridge structures, ultimately enhancing the insulation and energy-saving efficiency of the houses. Simultaneously, an energy-saving analysis is conducted based on an optimized enclosure structure scheme, considering seven key design factors that influence building energy consumption: span, depth, clear height, and window-to-wall ratio in all four directions. Through a comprehensive experimental method, the building energy consumption is evaluated, and a scheme with optimal values is proposed. The results demonstrate that the insulation block walls and the main structures with expanded insulation layers and low thermal bridge structures are easier to construct. When compared to the original scheme, the comprehensive heat transfer coefficient of the walls is reduced by 54.82%, while that of the beams and columns is reduced by 97%. Implementing the optimal value scheme leads to a reduction of 66.83% in the building’s overall energy consumption. This research provides valuable guidance for the design and construction of large-scale insulated block rural residences, revealing the substantial potential of rural residences in terms of energy-saving and emission reduction. Full article

The safety assessment of bridges in cold areas under the special environmental effects of extremely low temperatures, frequent freezing and thawing, and chloride ion erosion from snow removal with deicing salt, presents challenges that requiring solving. Thus, this paper proposes a new method of safety assessment based on a combination of Monte Carlo simulation (MCS) and Bayesian theory that achieves the reliability evaluation and reverse diagnosis of the overall safety performance of reinforced concrete bridges in cold areas. Additionally, the new method accomplishes the intelligent grading of various safety performance aspects of the bridge, which provides substantial references for the maintenance and reinforcement of in-service bridges. Full article