Silica technology
The silicate technology is based on silicon as an element and opens up by the reaction of inorganic or inorganic-organically modified silicates . The most important representatives on the raw material side are water glass , blast furnace slag (geopolymers) and fly ash . The coatings and materials of the silicate technology are characterized by an excellent resistance to acids, UV weathering and temperature, in some cases also to alkaline solutions , abrasion and solvents.
history
Historically, silicate technology products based on water glass have long been used for paints and paint systems ( mineral paint , germ paint ). Organically modified systems have been around for some time as silicate and silicone resin paints. Mineral systems became accessible through the availability of slag sand and so there are now various systems based on alkaline activated slag sand ( geopolymer ). Also alumino-silicates, based on aluminous have become established.
New developments
New developments in geopolymeric silicate binders are based on one-component, highly chemical-resistant silicate systems that are implemented through the alkaline activation of blast furnace slag with powdered water glass. The pressurized water-tight, shrink-free, environmentally friendly systems are free of calcium hydroxide and therefore have excellent acid and alkali resistance (pH 0-14).
In contrast to cement-bound building materials, an amorphous silicate gel (SiO 2 x nH 2 O) forms in the hardened binder with alkali-silicate mortars . In contrast to cement-based building materials, these alkali silicates, also known as hydrogels , are resistant to all inorganic and organic acids (except hydrofluoric acid ).
Due to the three-dimensional cross-linking of the silicate structures, very stable systems can be created that have compressive strengths of up to 95.3 N / mm² (7 days), 131 N / mm² (28 days) and flexural strengths of up to 10.41 N / mm² (7 days) or 11.67 N / mm² (28 days). Investigations at the University of Dresden have shown that this three-dimensional cross-linking is very well suited to binding even the very smooth carbon fibers very tightly (initial crack stress> 200 N / mm², stress-strain relationship at 13.3% elongation> 1,200 N / mm²). In addition, the SEM images show the excellent marginal fit to the embedded filler grain and the water pressure-tight silicate matrix.
use
These water pressure-tight and highly chemical-resistant structures can also be used for sealing and re-profiling sewage systems. It has been shown here that the silicate structures have a higher tightness than corresponding cement-based or polymeric sealing systems.
The processing of the geopolymeric silicate binders is identical to the previously used polymer or cement systems. All existing coating processes and machines can be used. In contrast to cement mortars, however, due to their dense packing and excellent adhesion to mineral and metallic substrates, they can also be used as thin-layer coatings and scratch fillers. Due to the good water vapor diffusivity, there is no risk of moisture condensation behind the coating, as is often observed in polymeric coating systems on moist mineral substrates.
Due to the excellent chemical resistance and the inorganic, quasi-ceramic composite structure, no corrosion of the surface is to be expected.
The adhesion to mineral surfaces is excellent thanks to the liquid binding agent water glass. Very good adhesion can also be achieved on steel. A polymer hybrid primer is only required to promote adhesion for polymers .
Environmental sustainability
By using blast furnace slag as the basic raw material, very environmentally friendly coatings and materials can be produced that have a very favorable CO 2 balance. These products are solvent-free and use water as an environmentally friendly solvent. Due to the low pH value (no Ca (OH) 2 ), it is easy and safe to process even for the processor without additional work protection.
There are different water glasses that differ in the metallic counterion . Sodium water glass is the cheapest but unfortunately also plant-toxic variant. Lithium waterglass is the most reactive variant, but it is very expensive and also not plant-friendly. Potassium water glass is available inexpensively as a bulk raw material and is the only representative with the plant fertilizer potassium as a counterion and is therefore very environmentally friendly.
Individual evidence
- ↑ M. Curbach, E. Lorenz: Investigations into the applicability of "Sinnodur-UHPC-casting mortar" as a high-strength fine concrete matrix for textile concrete. (PDF; 753 kB) Technical University of Dresden, Faculty of Civil Engineering, Institute for Solid Construction, Dresden 2010.
- ↑ J. Rathenow: Final report on HA project 181 / 09-11, silicate technology based on nanotechnology for coatings and pipeline construction. Sinnotec Innovation Consulting GmbH, Wiesbaden 2010.
- ↑ B. Bosseler, M. Gillar, M. Liebscher: Rehabilitation of sewage shafts - investigation of materials and systems for sealing and coating. Part 2 Local sealing measures. (PDF; 608 kB) KA 2011 (58), No. 9, pp. 814–824.
- ↑ M. Liebscher, M. Gillar: Rehabilitation of sewer manholes, investigation of materials and systems for sealing and coating, final report on the research project rehabilitation of sewer manholes. (PDF; 15.8 MB) AZ: I-2-ZV-2.1-08 / 068 and I-2-ZV-2.1-08 / 068.1 (IV-7-041 105 0251), IKT, Gelsenkirchen 2011.
