Developments in the Built Environment最新文献

This work reports an upgrading reuse of construction-generated sludge waste (CGSM) to manufacture value-added building materials using hydrothermal mineralization (HM). The optimization of mixture proportions and the influential factors of curing temperature and duration were explored. Results showed that high-strength HM-CGSW blocks over 50 MPa with a strength-to-calcium ratio of 2.95 MPa/percentage can be produced under an optimal Ca/Si ratio of 0.5 and HM curing of 200 °C for 12 h. The production of HM-CGSW block would generate 305.81 kg e-CO₂/m³ and cost of 222.44 CNY/m³, lower than those of concrete block and autoclaved fly-ash block. An industrial application of HM-CGSW was proposed for upgrading use of CGSW to produce building materials for new constructions. The findings in this study would not only deepen the mechanistic understandings of HM treatment of sludge waste, but also shed much light on developing an industrial path that enables sustainable building material production.

This study investigates the high-value recycling of stone wool from construction and demolition waste into alkali-activated lightweight insulation aggregates, designed for ground cover insulation. Various proportions of milled and as-is stone wools are alkali-activated to produce aggregates. The aggregates demonstrate loose bulk densities ranging from 720 to 850 kg m⁻³ and dry thermal conductivity from 0.075 to 0.094 W m⁻¹·K⁻¹, with moderate water sorption capacities. The fibre morphology of as-is stone wool influences rheology, introducing a greater number of pores or defects, which results in a decrease in mechanical strength. Hydrothermal simulations reveal that the floor assembly of the rehabilitated crawl space, partially filled with the fabricated aggregates, shows a reduction in water content and an increase in floor surface temperature. This observation suggests potential benefits for maintaining the structural integrity of buildings and enhancing occupant comfort.

Current research in air-conditioning and mechanical ventilation (ACMV) operation focuses on isolated sub-processes and analytical models. Digital twins, as digital replicas of assets, processes, or systems in the built environment, enable facilities manager (FM) to gain insights into the physical features of space, equipment performance, and energy efficiency. This study presents the 3D reconstruction of semantic-rich digital twins, which encompasses conditional and machine learning-enabled monitoring with 3D geometric models, for ACMV modeling and operation. The proposed framework involves a hybrid rule-based and data-driven approach to forecast the performance of indoor environment and identify potential anomalies throughout ACMV operation. Following this, a scan-to-BIM process is undertaken, with the aid of Simultaneous Localization and Mapping algorithms, to semi-automatically generate the as-built geometric models. Lastly, semantic enrichment of BIM is performed by incorporating time-series data from the rule-based and data-driven approach with 3D geometric models. The proposed approach supports the reconstruction of content-aware and semantic-rich digital twins, which utilize sensor-derived time-series data and 3D geometric models, to conduct advanced analysis for intelligent ACMV operation towards energy efficiency and occupant comfort.

The Industry Foundation Classes (IFC) schema is an open format for BIM models that secures permanent data availability independent of software vendors. This is particularly important for public stakeholders such as building authorities. However, during code compliance checking of the permit process, new explicit data are generated from information implicitly contained in the building models. This information has been available only in the checking application used and not independent of it. This paper presents an approach for generating a new IFC domain model from generated escape route results to be used by the building authority. This was achieved by defining the general concepts of how escape routes can be represented by building models and mapping these to IFC entities. A prototype implementation demonstrated the applicability of this approach. In addition to independent permanent archiving, the IFC domain model for escape routes enables the use of this data during building operations.

Both the hydrolysis instability of original long afterglow phosphors (OLP) and limited amount of reflective powders (RP) degraded the luminescent performance of self-luminescent cement-based materials (SLCM). This study novelty proposed a solution by coating organosilicon layer on the OLP surface to create hydrophobic effect for enhancing its water resistance. Furthermore, compared with typical SLCM with low content of LP and RP, SLCM mixtures were prepared through replacing cement by LP and containing higher volume of RP according to the modified Andreasen and Andersen (A&A) model. The effects of dosage and surface modification of LP on the strength, hydration kinetics, luminescent performance, phase composition and microstructure of SLCM were examined. Hydrophobic LP (HLP) achieved similar crystal structure but changed its surface morphology as well as enhanced its water resistance. Introduction of the OLP into SLCM was liable to generate the hydrolysis products. HLP performed better in generating more hydration products but less hydrolysis products, thus formed a compact microstructure and enhanced the thermal stability. Hydration kinetics revealed that the hydrolysis reaction of OLP decreased the heat of hydration, while the hydration process was promoted by HLP. Higher dosage of LP after hydrophobic modification in SLCM helped in obtaining a better luminescent performance but caused a drastic reduction in strength. Overall, the optimal dosage of HLP in SLCM including higher volume of RP was more effective in achieving a superior luminescent performance without degrading the strength.

The passivation evolution of mild steels in simulated concrete pore solutions with varying pH were systematically investigated in present study. Based on electrochemical, time-of-flight secondary ion mass spectrometry, and ReaxFF molecular dynamics simulation, a plausible model with high logical coherence and theoretical soundness was proposed to elucidate the underlying passivation mechanism. The results depict that the steels within concrete pore solution with high pH facilitates quick and compact film formation, leading to superior passivation performance. Spontaneously-induced passive film of mild steel demonstrates a dual-layer structure composed of an inner layer rich in Fe(II) and an outer layer rich in Fe(III).

Industrial clusters are conducive to accelerating the adoption of green technologies and green buildings, but the underlying mechanism of cluster-based adoption among different stakeholders is seldom examined. The paper aims to explore the diffusion mechanism of green building among stakeholders in industrial clusters based on an agent-based modeling (ABM) approach. Factors influencing stakeholders’ adoption of green buildings were identified in five dimensions: economic benefit, green responsibility, peer effect, market demand, and technological maturity. An ABM model was developed for simulating green building diffusion among stakeholders, and validated with a Shenzhen case. The results indicate an S-shape trend of the adoption rate within the cluster. Developers show a relatively laggard adoption compared to others. Mandatory policy and financial subsidies could effectively boost the adoption rate, while technological progress and market demand accelerate the diffusion progress. The study provides useful insights into the practice and policy-making of green buildings within industrial clusters.

The vertical transmission of bioaerosols in building drainage systems is an understudied route of disease spread. This research examines how the position of drainage floors, flush volume, pipe type, and building story number affect the dynamics and reach of bioaerosols in such systems. Our findings show that drainage points positioned lower in a building amplify the number of the affected floors above, with recorded pressure differences at various drainage points ranging from 900 to 3200 Pa, depending on flush volume and floor position. The transition to a double pipe system significantly reduced pressure differences (to as low as 330 Pa in vent pipes), thereby diluting bioaerosol concentrations but increasing their dispersion across more floors. Building story number further influenced bioaerosol spread, with higher buildings exhibiting negligible pressure differences across stories (1400–2300 Pa) but a pronounced increase in affected floors above the drainage site.

Manpower demand for construction projects is roughly budgeted based on planners’ personal experience. This research study explores an analytical way to characterise project labour demand profiles throughout project duration. Labour multiplier (LM) approach was advanced to characterise the labour demand profiles. Optimistic, most-likely, and pessimistic LM and labour demand profiles at 10 project stages are defined by using manpower and payment data derived from 91 completed public construction projects under 21 project types in Hong Kong. The root-mean-square-error and root-mean-squared-logarithmic-error are used to quantify the difference between the budgeted and the benchmarked manpower. A text-book example is successfully adopted to demonstrate the steps of the proposed approach, validated by two practical projects. This research is the first to study the use of LM to characterise optimistic, most-likely, pessimistic resource demand profiles for validating manpower resource budgets. Also, the approach provides a basis to evaluate the reasonableness of planned resource.

This study investigated the preparation of cementitious mortar specimens (ECM) by blending different dosages of pure magnesium hydroxide (AR), active magnesium oxide, and nano magnesium hydroxide as external additives with expired composite Portland cement. The optimal solution was selected by comparing their “nuclear magnetic resonance” (NMR), mechanical properties, and acoustic emission characteristics. NMR experiments revealed that the addition of 4 wt% nano magnesium hydroxide to expired cement resulted in the largest decrease in harmful pore content in ECM, reaching 21.9%. Mechanical performance testing and acoustic emission monitoring results indicated that the strength of ECM reached a maximum of 21.356 MPa with the addition of 4 wt% nano magnesium hydroxide, representing a 20.2% increase compared to the control group. This suggests that adding 4 wt% nano magnesium hydroxide to expired cement is a preferable option.