- Written by Dipl. Ing. Bernd Lübbert, Claudius Peters Projects
A number of different factors have to be taken into consideration in the selection of bag filling systems for mortar and gypsum products. The filling process and filling time are essentially determined by the product and material characteristics, as well as by the chosen filling system. By means of measured bulk density characteristics such as flowability, aeration behaviour, bulk density, grain size distribution, fineness and wear behaviour, mortar and gypsum products can be evaluated regarding their filling behaviour. This measured data can be used for the selection of a suitable filling system.
In order to be able to make a reasonable pre-selection of a powder filling system, the characteristics of the bulk material have to be determined. For this purpose, a standard dust test report is used. By means of the determined features in the dust test reports a classification regarding the filling system can be made with a modified Geldart diagram.
After the pre-selection of the filling principle either by turbine or by air filling principle the bulk material is examined at a test filling station regarding the filling times, weighing accuracy and the mass flow in coarse and fine flow. The evaluation of the results either confirms the assumed pre-selection or other filling systems have to be tested. For the filling tests the characteristics such as bag volume and air permeability of the valve bags to be used must be available (bag test certificate). Figure 1 shows the selection procedure in each steps.
- Written by Dustin Neumann, Neumann Process Control, Inc.
When building products manufacturing volumes are low, there is more competitive pressure to produce high-quality wallboard and the importance of maintaining customer loyalty by minimising claims becomes increasingly important. This article describes operational strategies for adjusting the dryer from volume-centric production methods to quality-centric methods during times of lower demand. Emphasis is placed on solutions requiring little or no capital.
In this time of reduced economic activity, there is limited demand for building construction and therefore builders and contractors are adjusting their competitive emphasis from capacity and speed of construction to managing costs and offering superior quality. It follows that building materials such as gypsum wallboard are scrutinised closely for quality and conformance to specification.
The consequences of quality complaints or claims are compounded in an environment of strong competition for a limited market. This article is a discussion of controlling the factors that result in quality claims. The general subject is dryer performance and although there are a number of aspects of product quality that are interdependent, such as mechanical handling, formulation and other factors, it is dehydration and finished moisture variability specifically that is the main focus.
Among the greatest risks for defective product entering inventory are variations that cannot be easily detected with the senses. Easy-to-detect deficiencies that result in complete paper separation, mechanical damage to edges and gross moisture variations that can be detected audibly or through handling are not emphasised. Finally, the definition of industry terms such as 'dryer balance' are further refined through the introduction of a model that facilitates discussion of the complexities of managing moisture variability.
- Written by Rupert Soar, Freeform Construction Ltd. & Peter Edwards, Global Gypsum Magazine
Have you ever wondered what buildings would be like if they were designed by Apple or made by BMW? What if buildings had the sleek design and efficient performance that we expect from a modern phone or car?
Today's aerospace, automotive and consumer goods industries make extensive use of highly integrated digital design, computer-controlled machining, moulding, forming and most recently, 3D printing techniques. This is because they have high performance materials such as polymers and metal alloys at their disposal. These materials and their processes bring about precision and tolerances not normally possible in mainstream construction because they are expensive to form at construction scales. This is something that Freeform Construction is looking to change by developing high-performance, technical 'freeform' α-gypsum products and processes for construction automation.
Here Global Gypsum Magazine's Peter Edwards and Freeform Construction's Rupert Soar jointly explore what might occur in the next phase of offsite construction. How might buildings become more sustainable, environmentally-sensitive and more beautiful than buildings seen before?
- Written by Simon Wintz, Claudius Peters Technologies S.A.
Stockyards are used in the gypsum industry for storage of natural or synthetic gypsum and act as a buffer storage or mixing facilities for combining different gypsum sources before calcining. For new projects, operators must consider capital costs and the operational efficiency of equipment and must choose between the virtually infinite possibilities offered by the market. Homogenisers, blenders or storage only and circular or linear storage are the main decisions. This paper attempts to clarify this selection process, with particular attention to the specific properties of gypsum.
Stockyard size and storage capacity
The first question to ask when designing a new stockyard project is the size in terms of storage capacity. The size of the storage capacity is not just proportional to the production capacity. It results from the combination of a feed and a reclaim process and is only a synchronising buffer between two different conveying flows. Even though raw materials have generally relatively low cost per tonne, the stored quantities must not be oversized unnecessarily.
- 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.