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Sustainable Construction Materials
Published in J.K. Yates, Daniel Castro-Lacouture, Sustainability in Engineering Design and Construction, 2018
J.K. Yates, Daniel Castro-Lacouture
In addition to the conventional building products mentioned in the previous sections, Sections 11.2 through 11.8, many types of unconventional building products are being designed and manufactured each year. BuildingGreen cited the following materials and processes in its list of the top 10 innovative products in 2007 (adapted from BuildingGreen 2006, p. 1): Electronically tintable glazing: The tinting of the glass is changed using an electrochromic control [changes with the amount of sunlight].Evaporative cooler: Indirect evaporative cooler.Interior molding: Molding profiles made with at least 90% recycled polystyrene.Interior panels: Panels for workstations, trim, or toilet partitions made with 40% pre-consumer-recycled copolymers.Irrigation system controls: Irrigation control based on local weather data.Polished concrete: Polish old and new concrete slabs into attractive, durable, and finished floors.System for salvaging timber: Harvest trees submerged in reservoirs created by hydroelectric dams.Water-efficient showerhead: A showerhead using only 1.6 gallons [6.1 L or 1.33 imperial gallons] of water per minute.Water-resistant composite: Solid composite material made from postconsumer paper.
The mechanisms involved during the wet braking of new and worn tires
Published in Vehicle System Dynamics, 2019
Violaine Todoroff, Sébastien Paupy, Frederic Biesse, Yohan Le Chenadec
To our knowledge, the first studies on this topic were written in the 1960s and 1970s [1,11–16]. Their authors analysed wet braking performance from tire and road perspectives. Those studies focussed mainly on locked wheel condition since no ABS system was available at that time. They demonstrated that a decreased tread depth (smooth tires were tested) combined with high speeds and high water depth had a huge impact on the friction value of the tested tires. They concluded that water film evacuation was crucial to ensure a good wet braking performance and they demonstrated that this could be achieved within the tire via high tread depth or within the road texture. As an example, those studies show that on smooth surfaces such as polished concrete, smooth tires with no sculpture to drain water displayed highly detrimental wet braking performances compared to the ribbed tires. On rough textures, drainage could be assumed by the ground and the wet braking performance of the smooth tire was less impacted.
Comparison of spacing factors as measured by the air-void analyzer and ASTM C457
Published in International Journal of Pavement Engineering, 2019
Will Lindquist, Rodney Montney
Various test methods exist to evaluate air-void systems in plastic and hardened concrete. Evaluations of both the plastic and hardened concrete are used by the State of Kansas to prequalify concrete paving mixtures and verify performance in the field. The air-void system in hardened concrete is determined in accordance with ASTM C457 which is the widely accepted method to determine the spacing factor based on work by Powers (1954). It is important to note that C457 spacing factor test results can vary by more than 50% and must be performed on hardened and polished concrete samples using a microscope or automated image analysis system (ASTM C457 2012). As a result of the relatively time-consuming procedure which includes coring hardened concrete, sawing the sample, lapping and measurement of the air voids, ASTM C457 cannot readily be used during construction to make real-time adjustments to mixture proportions. Instead, the test method is frequently used as a diagnostic tool to evaluate existing concrete.
Measurement of entrained air-void parameters in Portland cement concrete using micro X-ray computed tomography
Published in International Journal of Pavement Engineering, 2018
Haizhu Lu, Karl Peterson, Oleksiy Chernoloz
Since the smallest entrained air-voids have such a strong influence on specific surface and , it draws attention to the appropriateness of the Thdmin cut-off of 3 pixels (air-voids with diameters <22.5 μm) employed in this study. The limitations of the μCT for the detection of the smallest of air-voids are also shared by the commonly used stereological methods based on reflected light from a polished concrete surface. This is a somewhat contentious issue, as ASTM C457 recommends that circular air-void intercepts of 10 μm be clearly distinguishable. However, ASTM C457 also recommends a sample preparation regime that employs final polish with a > 10 μm diameter abrasive. It is doubtful that this level of preparation is sufficient for the detection of air-voids in the size range of 10–20 μm in diameter. ASTM C457 also recommends a minimum magnification of 50x, which is arguably insufficient for the detection of such small air-voids. Whether or not air-voids in the size range of 10–20 μm in diameter are measured during an ASTM C457 traverse is debateable. While beyond the scope of this paper, a broad survey of collected ASTM C457 chord intercept data would be informative, and help to settle this issue. Certainly, it is possible to carefully prepare and examine a polished specimen at a high enough magnification to observe 10–20 μm diameter air-voids, as well as hollow-shell (Hadley) cement grains of similar size, but this is not realistic within the practical application of ASTM C457, nor is it practical for the μCT method described here.