Application for wax dispersions.
Publication Date: 2005-Jun-10
The IP.com Prior Art Database
Madelein vd Merwe: ATTORNEY [+2]
This invention relates to a new field of application for wax dispersions. It relates to application in cement and lime products.
HydroWax™ impregnates Cement- and Lime
This invention relates to a new field of application for wax dispersions.
It is well known that lime can be used in the improvement and stabilization of soil. The Romans and Chinese already knew that lime stabilizes soil by dehydration.
Today this principle is still used. For the stabilization of sub grade of roads, railroads and other constructions fine-milled quick lime or cement is used. The “hydraulic soil stabilization” allows a quick construction start without a need for expensive soil compaction. Often the expense of exchanging difficult soil types can be saved. Cement is normally used for dry sand soils whilst lime is utilized for clay types. Frequently both products are used in blends precisely adjusted to the existing soil type. During treatment water absorption capacity is reduced. This leads to an increase in the freeze and thaw stability. The main reaction of these components is the transformation of calcium oxide by water absorption to calcium hydroxide. As a result of this reaction quick lime water absorption capacity is around 300 g per kg. The produced heat reaction which occurs during this process delivers an additional drying effect. In comparison to lime the cement gives the soil a stabile structure due to the content of siliceous material.
On the whole this type of soil stabilization reduces the typical settling effects in constructions (e.g. cracks) significantly.
For soil stabilization the lime or cement is first spread over the soil, worked in by special machines and then compacted by rollers. Difficulties occur if it rains. The rainwater reacts with the lime or cement thus preventing these from achieving their desired purpose. One possibility to continue work despite wet conditions is the use of hydrophobic (water repellent) products. These products are protected against rain water by an impregnation e.g. with Stearates, Silicones and Polymers. This coating is mechanically destroyed during the working in process. This ensures that the reaction with the wet soil really takes place.
Wax dispersions of typically mineral oil waxes or FT (Fischer Tropsch) medium waxes are most suitable. These wax dispersions show some advantages which make them attractive for an application as hydrophobizing agent. They are liquid at room temperature which simplifies the application technique. Another advantage is that dispersions contain countless tiny wax particles (~0,001mm) this enabling the coating of the lime or cement surfaces with low amounts of dispersion. This is crucial because too high amounts of wax act as a release agent thus reducing the mechanical stability of concrete. Because of this there exist official limits of such additives in the industry.
Experimental testing to illustrate the invention comprised initial testing on standard dispersions whereby wax dispersions were sprayed directly onto the...