In Europe, around 2380 million m² of gypsum boards
are produced annually in 72 plants. There are also some factories that produce gypsumblocks, plaster
elements and plaster molds. The foreseeable phase-out of coal-fired power plants
will lead to bottlenecks in the supply of FGD gypsum. Alternatives from natural
resources are not available in unlimited quantities in the desired quality. The
use of less suitable gypsum or the use of recycled gypsum poses new challenges
for Sika.
Our competence
From a large number of Sika products, we have clearly arranged the product groups relevant to the gypsumblock and plasterboard industry. From adjustment consistency and saving water for setting control and adjusting raw densities and board weights through to the production of perfect surfaces. Sika offers everything from one hand. Of course, we still have a lot of specialties in our portfolio and we are constantly working on new products.
High Performance Superplasticizer
Sika® ViscoCrete® – high-performance superplasticizers are based on PCE (polycarboxylate ether) technology. The production takes place in compliance with strict industrial standards and ensures a continuously high product quality. By knowing the effect of different polymer designs, Sika® is able to offer tailor-made solutions for a variety of
applications with different binders.
Sika® ViscoCrete® superplasticizers have a double-action dispersion effect:
1. By saturation of electrostatic charges on the particle surface
2. By steric repulsion of the PCE molecules.
The most important advantages at a glance:
- Strong liquefying effect event at very low dosages
- High water reduction possible
- Short mixing times
- Allows formaldehyde-free formulations
- Good compatibility and synergies with other additives
- Consistent quality
- Available worldwide
- Also availablel as a powder if there is a risk of frost
Retarder
Begin and end of setting of plaster of paris can be precisely controlled by using additives. Additives which act on nucleation - especially the retarders and accelerators based on dihydrate - have a much stronger effect than substances which influence solubility. The use of calcium sulphate beta-hemihydrate in combination with highly effective accelerators, especially finely ground gypsum, is currently state of the art and is generally known.
The crystal growth of gypsum begins immediately after the binder comes into contact with water. Modern production lines in plasterboard plants require the hardening process to be completed in significantly less than 10 minutes. This can only be achieved with high doses of accelerator, often in the range of 0.5%. In many cases this does not happen in the required processing time of a few seconds until the stiffening of starts. The negative consequences of premature hardening occur inside the mixer and on the production table: the flow dimension deteriorates or caking and lumping can occur, what can result in both in disruptions in the manufacturing process and lower plasterboard quality.
This is why a combination of retarder and accelerator is used in the manufacturing-process of plasterboard in order to create an ideal setting curve, which is characterized by a slight extension of the resting phase and afterwards rapid setting. The so-called "Snap-Set" avoids problems in the mixer and ensures a high degree of hydration (95 - 98%) before the panels are cuted and dried. In addition, the strength in the panel core is improved, which is particularly desirable in the production of lightweight panels. The use of Retardan® enables the systematic incorporation of foam into the liquid gypsum mass, keeps the mixer clean and improves the wet bond between the cardboard layers. Retardan® products are appreciated for their well-defined delay.
The most important advantages at a glance:
- Postponement of the start of hydration without loss of intensity
- No inhibition of crystal growth (in contrast to fruit acids)
- Rapid strength development and higher final strength
- Consistent quality and worldwide availability
- Defined productions with synthetic raw materials under controlled conditions
Air Entrainer
Sika foaming agents are combinations of different surfactants which, when using a foam generator, produce a fine, very stable foam, e.g. for the plasterboard
industry. Without a foam generator, using mixing energy alone, a very stable and almost optimally coordinated foam structure is achieved in conjunction with Sika® ViscoCrete®.
Release Agent
Release agents should prevent the gypsumblock and mold from sticking together. In order to be able to fulfill this function, the used release agent must form a continuous film on the surface of the formwork and thus prevent any contact between the casting and the mold. Sika is a leader in the field of environmentally friendly emulsion-based release agents with very low consumption for beautiful and even surfaces. Vegetable oil as a raw material base ensures sustainability and excellent biodegradability.