Developments in the Built Environment最新文献

This study investigated rheo-viscoelastic behaviors of MgO-SiO₂ pastes with three phosphate additives (sodium hexametaphosphate (SHMP), sodium trimetaphosphate (STMP), and sodium orthophosphate (SOP)) as superplasticizers. Static yield stress, dynamic yield stress, median differential viscosity, thixotropic loop area, structural recovery rate, and non-destructive structural build-up were analyzed. Furthermore, assessment of hydration and particle dispersion stability was facilitated by employing isothermal calorimetry, XRD, DTG, and zeta potential techniques. SHMP significantly decreased the static and dynamic rheology, thixotropy, and viscoelastic evolution. Samples incorporating 2 wt% SOP exhibited enhanced rheological parameters, particularly static yield stress, owing to increased brucite formation and a denser microstructure in the fresh paste. Adsorption of phosphate additives on MgO surfaces inhibited formation of brucite and improved interparticle electrostatic repulsion, thereby increasing suspension stability. High-efficiency adsorption of SHMP on MgO surfaces, coupled with the retardation of brucite nucleation-and-growth, and enhancement in suspension stability, greatly restrained the rheo-viscoelastic evolution of MgO-SiO₂ system.

The research aims on thermophysical properties of an ancient silver fir wood using transient plane heat source method in three directions of wood defined under isotropic environment. Crucial parameters studied at room temperature include thermal conductivity, thermal diffusivity, thermal effusivity. Analysis of measured thermal responses were done with respect to the full range of time window interval and shortened interval chosen for fitting by model. The depth of heat penetration was investigated with an emphasis on the criteria for evaluating the thermal response published literature (Boháč et al., 2000). The findings support the challenges and understanding of the interaction of wood's orthogonality loaded when interacting with different heating powers (25, 40, 50, 70) (m W) with time (s). The inhomogeneous structure for different levels of thermal energy provided valuable insights into the complex nature of wood and essential for applications requiring heat management such as preservation, construction, material engineering, in specific direction of wood structure.

Masonry units have been fundamental to building construction for over 6000 years, making them one of the oldest and most widely used materials in the industry. However, their production using ordinary Portland cement has significant environmental impacts, including high carbon dioxide emissions and depletion of natural resources. This highlights the need for more sustainable alternatives. One promising option is the use of recycled aggregates from construction and demolition waste in masonry unit manufacturing. This paper investigates the use of chipped waste timber as aggregates, bound together with geopolymer cement made from industrial by-products such as fly ash and slag. The result is a new type of masonry units, referred to as wood geopolymer masonry units (WGMUs), which were evaluated against established standards and compared with conventional masonry units (CMUs). The innovative WGMUs demonstrated improved ductility and reduced density compared to CMUs, making them easier to handle and lighter in construction. They also have a distinctive, rustic texture and consistent dimensions that meet Australian standards. Although WGMUs exhibited higher water absorption and drying contraction due to their wood content, these characteristics generally remain within acceptable limits, supporting their potential as eco-friendly construction materials.

Daylight spectral simulation is crucial for designing functional, healthy spaces and predicting light interactions. It is essential for accurate non-image-forming effects of light calculations. This study addresses the knowledge gap in reproducing indoor daylight spectral conditions in the built environment. Using varying levels of geometry (LOG) and information (LOI), simulation accuracy was assessed by comparing it with experimental data from two offices over three days with cloudy and clear sky conditions. The lowest accuracy was found with high LOI and low LOG simulations. For the highest accuracy, specific material spectral properties are needed, while spectrally-neutral materials at low LOG produced comparable results. Simulations near and facing windows were the most accurate. The study concludes that to reproduce indoor daylight spectral conditions, modelling should use either the lowest or highest geometry and information complexity, depending on available modelling time and required accuracy.

Geopolymers represent a promising solution for reducing carbon emissions in 3D printing concrete (3DPC). This study explores the utilization of waste glass powder (WGP) as a novel precursor material to evaluate its influence on the printability and hardened mechanical properties of 3D printing geopolymer concrete based on slag and fly ash. Experimental results indicate that WGP content below 10% accelerates hydration and enhances buildability, whereas content exceeding 10% slows hydration but improves extrudability. Mechanical tests on cured specimens demonstrate a notable increase in compressive and flexural strength with increasing WGP content from 0% to 20%. Microstructural and chemical analyses of the 20% WGP variant reveal a denser morphology and an optimized Si/Al ratio.