CZ28822U1 - Internally hydrophobic lime mortar - Google Patents

Description

Technical field

The present utility model relates to the composition of a dry mortar composition for the production of an internally hydrophobic lime mortar with reduced water absorption. Due to these properties, the mortar is suitable for use in locations with repeated penetration of liquid water from the outside. The proposed mortar mix does not contain cement, which in addition to the normal use also allows the use of mortar for restoration of historic buildings and monuments, where the use of cement is questionable.

Background Art

At present, dry mortar mixtures with hydrophobic additives are produced industrially on the Czech market, in which the binder is most often represented by cement. For the repair of most historic buildings, lime mortar or mortar bonded naturally with hydraulic lime or lime-lucola binder is preferred in terms of compatibility with historical masonry.

Metakaolin is a suitable pozzolanic and relatively easily available pozzolanic additive. Compared to pure lime air binder (lime hydrate), metakaolin-modified lime mortars achieve higher strengths, mature faster, have higher resistance to frost and salt damage, while retaining sufficient porosity and vapor permeability typical of lime materials.

The problem requiring a special solution remains the composition of plaster for historical structures exposed to particularly harsh weather conditions (facades and masonry heavily loaded with water, frost and penetration of water-soluble salts). Resistance and durability of lime and limometakaolin plasters is not sufficient in this environment and exposure.

The object of the invention is to propose a dry mortar composition which can be used for the production of low water absorption mortar containing lime hydrate or hydrated lime with pozzolanic admixture.

The essence of the technical solution

The essence of the technical solution of lower absorption of lime / lime-calcium mortar is to optimize its wettability. The addition of a hydrophobic additive results in a change in the physico-chemical properties of the mortar (the water's wetting angle varies).

The main feature of the invention is the use of a hydrophobic additive in an amount of 0.015 wt. part to 8.5 wt. other components of the dry mortar mixture. The hydrophobic additive is linseed oil. The addition of linseed oil leads to a reduction in capillary water absorption (capillary water absorption rate) of the hardened mortar.

Dry mortar mixture for the production of lime internally hydrophobic mortar contains mortar sand with continuous grain size curve with grain size 0 to 4 mm, white lime slaked CL 90 in the form of lime hydrate powder with grain size between 0 and 63 µm, linseed oil or metakaolin with grain size ranging from 0 to 10 µm. The dry mortar mixture is suitable for the preparation of mortar, which is characterized by low water absorption and consequently a longer service life (frost resistance to a higher number of freezing cycles and higher salt resistance) compared to lime plaster or lime plaster, without linseed oil.

Example of realization

The composition of the dry mortar mixture for the production of lime internal hydrophobic plaster is shown in Table 1.

-1 CZ 28822 Ul

Table 1 - Relative weight composition of dry mortar mixture

Component Lime mortar Limpucollan mortar Lime hydrate 1 part 0.75 parts Pozzolanic admixture (metakaolin) 0 0.25 parts Aggregates 7.5 parts 7.5 parts Linseed oil 0.015 parts 0.015 parts

The optimum preparation of fresh mortar from dry mortar is as follows: Aggregate, lime hydrate, in the case of lime-calcium mortar also metakaolin, are mixed, then a small portion of the dry mixture (approximately 5% of the volume of the mixture) is mixed in a suitable sized container with linseed oil several more small portions of the dry blend (3 x about 5% of the volume of the blend) are added to the blend to effectively mix the blend. The oil mixture is then added to the dry oil-free mixture and mixed. Furthermore, water is added in such a quantity that the mortar has a suitable consistency for application.

The capillary absorption of hardened plaster was tested according to ČSN EN 1015-18 (Test methods for mortar for masonry - Part 18. Determination of the capillary absorption coefficient of water in hardened mortar) and showed a reduction of the capillary absorption coefficient of mortar with the addition of oil by 80% compared to the reference mortar without addition oils. The durability of the plaster was significantly increased due to increased resistance to plaster crystallization and freezing cycles.

Industrial usability

The dry mortar mixture according to the technical solution can be industrially produced for use in the construction industry for both new buildings and for the renovation and restoration of historic buildings and heritage sites.

Claims (2)

PROTECTION REQUIREMENTS A dry mortar composition for the production of an internally hydrophobic lime mortar, characterized in that it comprises 7.5 wt. parts of aggregate with a grain size of 0 to 4 mm, 1 wt. % of CL 90 lime hydrate having a particle size of 0 to 63 µm and 0.015 wt. of linseed oil. 2. A dry mortar composition for the production of an internally hydrophobic lime-metakaolin mortar, characterized in that it comprises 7.5 wt. parts of aggregate with a grain size of 0 to 4 mm, 0.75 wt. 0.2 part by weight of CL 90 lime hydrate having a particle size of 0 to 63 µm; % of metakaolin having a particle size of 0 to 10 µm and 0.015 wt. of linseed oil.