Abstract:
There are provided gypsum panels, sheets and multi-layer sheets as well as methods of preparation thereof. For example, there are provided cellulose filament-reinforced gypsum panels, sheets and multi-layer sheets and methods of preparation thereof. For example, in such gypsum panels, sheets and multi-layer sheets gypsum is bound with cellulose filaments to strengthen the gypsum panels, sheets and multi-layer sheets. The cellulose filament-reinforced gypsum panel can be, for example, a core comprising a honeycomb or corrugated structure. There are also provided aqueous suspensions comprising cellulose filaments and CaSO 4 •2H 2 O.
Abstract:
A cementitious product with strengthened composite structure is provided. Energy-efficient methods for manufacturing such products are provided as well and include dewatering a partially-set cementitious product by applying vacuum, and also creating a concentration gradient across the product thickness. Systems for manufacturing such products are provided as well.
Abstract:
The invention concerns an energy-saving method of producing environmentally-friendly panel-like components, in particular panel members (22), from fibrous materials (4) or the like and hardenable binders for the fibrous materials (4). According to the invention, the fibrous materials (4) have an aqueous moisture portion of substantially 40 to 80 wt.% and are mixed with calcined calcium sulphate (gypsum), the moisture portion being released to the gypsum. The mixture is applied to a rigid, flat substrate (20), compressed thereon by pressure, and, under pressure, is subjected to a dwell time dependent on the setting of the calcined calcium sulphate (gypsum).
Abstract:
Fibre-reinforced plaster plates are produced according to a single layer, continuous filtration process. A suspension of hemihydrate plaster and wet processed lignocellulose-containing fibres, preferably from used paper, is dewatered on a travelling screen. The apparent density of the plaster used is higher than 950 g/l, in the case of a alpha -hemihydrate plaster, and than 700 g/l, in the case of beta -hemihydrate plaster. In the RRSB-grid, the grain of the plaster has more than 40 DEG gradient. beta -hemihydrate is aridized during calcination. The fibrous substance is pre-dewatered before being mixed with the plaster-fibre-suspension, then rediluted with water from the filtration process. The dewatering of the suspension is assisted in the last stage of vacuum filtration by vibrations or shearing forces. Devices for distributing the suspension and for generating the shearing forces are also disclosed.
Abstract:
A pressing assembly (10) and a method for forming a depression (105) within a moving, wet gypsum board (100) is disclosed. The assembly comprises a pressing head (16) comprising a pressing surface which is arranged to contact the board, and a support member (17), the pressing head (16) being arranged to compress a portion of the board between the pressing surface and the support member (17) to form a depression (105) within the board (10). The pressing surface comprises a first and second surface portion (24, 25) separated by a relief portion (27), which is arranged to press the board (100) toward the support head (17) with less compressive force than the first and second surface portion (24, 25). The assembly further comprises drive means (18, 19, 22) for moving the pressing head and the support member in a first direction which substantially corresponds with the direction of the moving board, and a second direction which is substantially perpendicular to a plane of the board, while the speed of the pressing assembly in the first direction substantially matches the speed of the board.
Abstract:
The invention relates to a method for mixing gypsum (A) (or another hydraulic binder) in which the mixture is placed in a mixing chamber (B) including an upper portion for introducing the gypsum and the mixing water, a medium portion substantially defining the active mixing area and including at least one outlet (K) in a flow relation with the mixing chamber, and a lower portion including a lift foam inlet (I) and an outlet (E) in a flow relation with the mixing chamber. The lower flow outlet formed on the entire width of the plate reduces the fluidity requirements of the paste, which results in reduced manufacturing costs and in an increase of the production capacity. The mixer device, due to the ratio between the diameter and the height thereof, allows for the in situ creation of a density gradient of the paste based on the height. The method for making composite plates with several longitudinal densities is thus made easier and more reliable due to the reduced overall dimensions of the mixer assembly and of the paste deposition device.
Abstract:
A method for forming a gypsum slurry comprises the steps of combining gypsum and water to form a slurry, combining cellulose ether with at least a second material configured to delay solubilization of the cellulose ether, and adding the combined cellulose ether and at least a second material to the slurry.
Abstract:
A cored construction product such as a hollow cored partition panel for a building is made from a compressed mixture of liquid settable powder and wooly fibrous material. The powder and fibrous material are mixed and evenly damped, and the resulting mixture is fed into a vertical mould cavity defined between a core former (11) and two opposed pairs of mould side walls (15, 16) which are movable towards and away from the core former (11) relative to static mould corners (19). The side walls (15, 16) are moved to compress the mixture particularly by means of inflatable tubes (24) bearing on the outer surfaces of the side walls. The side walls are held in position until the mixture sets and the product is then removed from the mould.
Abstract:
A method and apparatus for producing gypsum board. The method includes the steps of mixing a predetermined amount of fibers, absorbent, and water to form a mixture of wetted, loose fibers, mixing the wetted fibers with predetermined amount of dry calcined gypsum, forming the mixture into a matt having a substantially uniform consistency and compressing the matt to form a board composed of bonded fibers and gypsum. The resulting board has a smooth exterior and can be a homogeneous or a multilayer board.