The role of social sustainability in building assessment

ABSTRACT

Can social sustainability be built? What are the challenges and potential for incorporating the concept of social sustainability into the assessment of building projects? Theoretical approaches to social sustainability are examined for the ways it is applied in practice by building industry stakeholders. A fundamental question is whether and how social sustainability can be measured, assessed and certified in the construction or renewal of housing and neighbourhoods. In addition to physical and functional indicators, it is suggested that certification systems (e.g. the Deutsche Gesellschaft für Nachhaltiges Bauen – DGNB) should also reward social initiatives. A framework was developed involving 12 indicators grouped three overarching themes: social cohesion; participatory processes; and accessibility to living opportunities. A collaborative case study project involving two Danish social housing neighbourhoods examines how social sustainability indicators could be integrated into the application of certification systems such as the DGNB and whether the certification system can be improved by integrating social and organizational aspects with the existing criteria for physical and functional layout. It is found that certifications must take the housing complex or neighbourhood's relationship with the surrounding city into account, as well as its development over time and flexibility towards future needs.     

Calcium Sulfate as a Possible Oxidant in “Green” Silicon‐based Pyrotechnic Time Delay Compositions

Chemical time delay detonators are used to control blasting operations in mines and quarries. Slow burning Si BaSO₄ pyrotechnic delay compositions are employed for long time delays. However, soluble barium compounds may pose environmental and health risks. Hence inexpensive anhydrous calcium sulfate was investigated as an alternative “green” oxidant. EKVI simulations indicated that stoichiometry corresponds to a composition that contains less than 30 wt‐% Si. However combustion was only supported in the range of 30–70 wt‐% Si. In this range the bomb calorimeter data and burn tests indicate that the reaction rate and energy output decrease with increasing silicon content. The measured burning rates in rigid aluminum elements ranged from 6.9 to 12.5 mm s⁻¹. The reaction product was a complex mixture that contained crystalline phases in addition to an amorphous calcium containing silicate phase. A reaction mechanism consistent with these observations is proposed.     

Hydrogeochemische Hintergrundwerte der Grundw?sser Deutschlands als Web Map Service

One of the main objectives of the EC water framework directive is to ensure good chemical status for all groundwater bodies. For this reason the geological surveys of Germany have produced a nationwide map of the background values of groundwater. Only naturally occurring inorganic parameters were taken into account, including the relevant major and trace elements. Based on the hydrogeological map of Germany at the scale of 1:200,000 (HüK 200), and its delimited hydrogeological regions, a total of 186 hydrogeochemical units were defined and mapped geochemically. This involved collection of more than 52,000 groundwater samples in a database and allocation to their appropriate hydrogeochemical units. In order to separate anomalies within the data-sets from the underlying normal population, probability nets were used as a statistical tool. The procedure allowed to determine the normal populations of the investigated parameters within the hydrogeochemical units and to quantify them in the form of percentiles. The resulting hydrogeochemical background values are accessible through an internet web map service that includes an online map application. The main intention of this technical note is to inform the reader about the existing internet service, which necessitates some web-site content duplication.     

Influence of Deformation on the Precipitation Behavior of Nb(CN) in Austenite and Ferrite

The evolution of Nb precipitates in a low-alloyed steel at 973 K (700 °C) as a function of strain and subsequent dwell time is studied via atom-probe tomography (APT) and transmission electron microscopy. The results show that the volume fraction of the precipitates increases with increasing accumulated deformation because deformation-induced dislocations act as nucleation sites. The chemistry of these precipitates which are Nb carbonitrides changes with the dwell time after the deformation step. With increasing time, the C fraction increases. The precipitation analysis by APT in the austenite and the ferrite reveals that precipitates in the ferrite are larger and exhibit a higher C fraction compared to the precipitates in the austenite after the same thermo-mechanical treatment. The investigations also show that the volume fraction of Nb carbonitrides in the ferrite is higher than in the austenite.     

Mechanical Properties of Ternary Blends of ABS + HIPS + PETG

The effect of a commercial styrene/butadiene/styrene-based compatibilizer (Styroflex) on the tensile and impact properties of ternary blends of poly(acrylonitrile-co-butadiene-co-styrene) (ABS), high impact poly(styrene) (HIPS) and poly(ethylene terephthalate-co-cyclohexanedimethanol terephthalate) (PETG) was investigated. The tensile yield strengths and the moduli of the blends were of similar magnitude as the parent polymers. However, notched Charpy impact properties showed significant deviations with high synergy in ABS/PETG blends and strong antagonism in HIPS/PETG blends. Addition of Styroflex improved the impact properties of all blends containing HIPS and ABS. Dynamic mechanical analysis studies confirm the phase separated nature of ABS/PETG binary blends.     

Masterbatch production of polyamide 6‐clay compounds via continuous in situ polymerization from caprolactam and layered silicates

Mechanical properties of thermoplastic polymers can be improved by incorporation of nanoscaled layered silicates. To achieve a significant improvement, the silicates have to be well exfoliated within the polymer matrix. However, it is not always possible to produce exfoliated nanocompounds with the standard procedure of melt compounding. As an alternative to melt compounding, an in situ process for the production of polyamide 6‐nanocompounds is investigated. During the in situ production, the layered silicates are dispersed in the monomer caprolactam prior to the step of polymerization in a twin‐screw extruder, leading to an intercalation of the silicate filler. The production of a polyamide compound containing 0, 2, and 4 wt % nanoscaled silicates was successful. Young's modulus was increased by ～ 30–60%. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Modeling of structural reaction injection molding process. I. Mathematical model

A mathematical model of the infusion process in producing reinforced articles is proposed. The model is based on the analysis of flow of a Newtonian liquid inside a rectangular multilayer channel. According to the model, a liquid enters the central (feeding) layer, moves through this layer, and simultaneously impregnates peripheral layers. So, the flow is two‐dimensional. Flow inside the porous layers is treated in terms of the Darcy equation with different permeability coefficients in two directions. Principal solutions for the flow front development and pressure evolution were obtained and analyzed. Then the initial model, developed for a Newtonian liquid, is generalized for the so‐called “rheokinetic” liquid, which changes its rheological properties in time as a result of temperature variation and/or any possible chemical process, in particular, the reaction of curing of a binder. It was proven that in this case the solution is automodel. This means that the solutions obtained for a Newtonian liquid in the dimensionless form are valid for an arbitrary rheokinetic liquid.     

Design, construction and testing of a chimney that reduces dangerous temperatures in a radiative convective solar dryer

One of the problems encountered in agricultural solar dryers that operate by natural thermo-convection is the “burn-up” of the products due to excessive solar radiation and/or low internal air velocity (insufficient chimney draft). This paper describes the design, construction and testing, in a solar dryer prototype, of a chimney of maximum draft intended to eliminate the above mentioned phenomenon. The results indicate that a slight geometry modification (keeping height constant) will increase air velocity by a factor of 2–3 with respect to a chimney of cylindrical shape, thereby decreasing product temperature approximately 10°C.