- Written by Ian Abley, Audacity
Higher thermal performance can be achieved by either installing more thermal insulation in a construction, or by using lower thermal conductivity insulation. This emphasis risks creating problems for constructions if other aspects of building codes are overlooked.
There is an opportunity for expressing the eco-thickness of architecture, but when development value puts a premium on floor space or storey heights, commercial attempts to make thinner walls and roofing are struggling with the uncertainties of product innovation. Foil-faced polyisocyanurate foams have not managed to achieve a lower than 0.021W/mK thermal conductivity. There is no full-fill polyisocyanurate foam product on the market and the reduction of air cavities in masonry walls from 50 to 25mm requires better workmanship.
Cavities behind rainscreen or ventilated coverings must be retained. Multifoil insulation products have received criticism and are now limited in their claims to performance. Silica aerogels are used in expensive internal dry-lining but cannot achieve a thermal conductivity below 0.013W/mK. It is increasingly recognised that only vacuum insulation panels (VIPs) can achieve lower than 0.005W/mK to offer the thinnest construction. Some VIPs promise thermal conductivities as low as 0.001W/mK.
- Written by Volker Schmitz, PCME Ltd
Volker Schmitz from PCME Ltd reviews established methods of measuring dust concentration in industrial installations and highlights the benefits of PCME's electrodynamic techniques.
Established dust analysis methods
Gravimetric techniques: Gravimetric sampling involves taking an isokinetic sample (ie: one in which the velocity of the sampling nozzle is the same as the stack) through a pre-weighed filter and then re-weighing the filter after a given time. One also measures the flow and can thus obtain the concentration of the dust in mg/m³.
It is the only method that gives the user a real concentration. All other methods are relative methods and must be calibrated accordingly. This means that to read concentration values using any other dust monitor, it first has to be calibrated using a gravimetric sample.
- Written by Xu Shengyong, Beijing New Building Materials Co. Ltd.
In the 1970s China began independent design and manufacture of gypsum wallboard production with a capacity of 4MM2/yr. In 1979 Beijing New Building Materials Company Ltd (BNBM) was established, pioneering the large-scale production of gypsum wallboard in China. It introduced the first modern, 20MM2/yr wallboard production line in the country and is now the market leader in China.
Compared to developed countries, China's paper-coated gypsum wallboard industry started comparatively late but developed very rapidly. With the rapid development of the economy, of the construction industry and the need to refurbish a large number of buildings, the market demand for paper-coated gypsum board has begun to surge during the 11th Five-Year Plan period. Wallboard has now become the dominant material for non-load bearing walls and suspended ceilings in China.
- Written by Dennis M. Mahoney PhD & Jonathon Stuart, Henry Company & D. Paul Miller PhD, Consultant
The process and chemistry of converting raw gypsum to a finished commercial board has been developed and refined over many years. Improvements to the process include improved board mixer and kiln designs as well as improvements to the chemistry both defined and non-defined by the process. Improvements have been achieved in terms of board-weight reduction, resistance to water and mould and specialised performance in areas such as fire-resistance and acoustical applications. The current process of wallboard manufacture has been refined to its current state with relatively incremental improvements to the technology with a significant focus on cost improvements exacerbated by the current economic environment.
The Henry Company, a supplier of wax emulsions to the wallboard industry, has completed a significant amount of work in developing and improving additives to the wallboard slurry that can help to improve the economics of the wallboard manufacturing process as well as improve the performance of the finished board. The focus of this work was directed at improving line speed, reducing energy demand and increasing board strength to allow density reduction and/or raw material cost savings. This effort has resulted in proprietary products that allow a reduction in water demand while maintaining the proper rheological profile of the slurry with a concurrent increase in board strength.
- Written by Derco Gypsum
The wallboard industry has become a challenging business, in which consumers demand virtually finished walls that do not need further treatment and fierce price competition forces manufacturers to work as efficiently as possible. In the process of efficient working, the forming line plays an important role and its belt is a weak link, having to be both reliable and consistently smooth. The belt's flatness determines the quality of production output, whilst downtime for installation, maintenance and repair lays a heavy burden on production efficiency and costs.
Having heard of its experience in the development and production of thermoplastic conveyor belts, global wallboard manufacturers approached Derco, asking it to find a solution for the many issues surrounding the forming line belt. Over recent years, the Derco Gypsum thermoplastic forming line belt has proved to be a very successful alternative for the conventional rubber belt. In this article we will explain why.
