CS215323B1 - Additive for plasticization and cement solidification control - Google Patents

Abstract

The application for the invention entitled "Additive for plasticization and regulation of cement solidification" solves the plasticization and regulation of cement solidification by adding a mixture of polyvinyl alcohol and triethanolamine, or possibly aqueous dispersions of macromolecular substances and surfactants. It improves the required properties of cement and the prepared mixtures are suitable for the production of self-leveling quick-setting mixtures, especially for the production of elements with structured surfaces, for grouting prefabricated elements, and with appropriate treatment with triethanolamine also for sealing

Description

BACKGROUND OF THE INVENTION The present invention relates to an additive for plasticizing and controlling the solidification of cement, which comprises polyvinyl alcohol as plasticizer, triethanolamine solidification regulator and optionally comprises aqueous polymer dispersions and / or surfactants which reduce surface water intake and prevent sedimentation of the cement composition.

The prior art cement binder modification additives are selective in nature and only affect some of the desired properties. E.g. Sodium salts of sulphonated melamine-formaldehyde oligomers (Rak. Pat. 263-07, NSR Pat. 936 673 J) or sodium salts of sulphonated naphthalene-malide oligomers (NSR Pat. 12 38 831) are used for plasticization. According to other methods, sulfonated dextrins (NSC Pat. 24 36 603), phenol formaldehyde oligomers (NSC Pat. 24 21 222), alkyarylsulfoacids, treated lignosulfonates (NSC Pat. 26 02 403) are used, which substantially retard the setting of cementitious compounds and reduce mechanical properties. As solidification regulators, calciteuminitrite (Franc. Pat. 1 498 369), gluconic acid and sallcylic acid derivatives (NSC Pat. 10 99 427), etc., are used. These solidification regulators acted separately and affect the plasticity of the cement mixture.

The above-mentioned drawbacks are overcome by an additive for plasticizing and controlling the solidification of the cement according to the invention, which contains, on a dry weight basis, 0.1 to 19.9 parts by weight of polyvinyl alcohol, 0.05 to 4.95 parts by weight of triethanolaimine or 3 to 18 parts by weight of an aqueous dispersion. macromolecular substances or redispersible polymers based on polymers or copolymers of wool acetate, afcrylic acid, alfcylacrylates and styrene.

Polyvinyl alcohol exhibits significant plasticizing effects in an alkaline environment, and these are exacerbated by the use of triethanolamine. Triehanolamine has a pervasive effect on cement and process solidification. The reaction of all soluble sulfate ions is accelerated. There is a dense network of crystals, which is fun! solidifying the mixture. At the same time, triethanolamine acts as a surfactant and reduces the tendency of the mixture to sediment. The prevention of sedimentation can be further influenced by the addition of alkali-stable surfactants, in particular nonionic ethylene oxide-based compounds. To increase the tensile, flexural and elastic modulus, aqueous dispersions of macromolecular substances can be added to the mixture, preferably combined with plasticisers and solidification regulators in the form of a single component.

The inventive cementitious compositions are suitable for the production of self-leveling, fast-setting compositions, for the production of rugged elements with rugged surfaces, such as e.g. View concrete, for prefabricated grouts, etc.

With an increased content of triethanolamine, these compositions are suitable for sealing cracks, joints, fast setting joint layers, waterproofing layers and the like.

Example 1

94 wt. % polyvinyl alcohol with a dry weight of 16 wt. and 6 wt. parts of triethanolamine. This additive is added in an amount of 2 wt. divided to 48 wt. water and the solution is used as a mixing water for a 100 wt. parts of cement (PC 325), 300 wt. parts of continuous granulometry with a particle size of 0.01 to 16 mm. The concrete mixture has a consistency of 12.1 with VEBE, a pourability of 59 cm and a setting point of 0.4 h. The mixture without additive has a consistency of 21 with VEBE, a pourability of 42 cm and a start of solidification of 1.8 h.

Example 2

68 wt. % by weight of polyvinyl alcohol having a dry weight of 50 wt. and 32 wt. parts of triethanolamine. 4 wt. the ingredients of this additive are mixed in 40 wt. parts of water and the solution is used as a mixing water for a dry mix containing 100 kg of white cement (PC 400), 490 kg of limestone grit with a grain size of 0.1 to 1.6 mm, Θ wt. parts of chromium oxide green and 4 wt. parts of aluminum sulphate. After homogenization, the mixture is applied to the undercoats by pouring. The mixture has a consistency of 6.5 with VEBE, a pourability of 68 cm and an onset of solidification of 1 wt. The mixture without additive has a consistency of 28 with VEBE, a pourability of 36 cm and an onset of solidification of 1.6 wt.

Example 3

The cement modification mixture is prepared by homogenizing 30 wt. % by weight of polyvinyl alcohol having a dry weight of 30 wt.%, 38 wt. parts of triethanolamm and 32 wt. % by weight of an aqueous dispersion of polyvinyl acetate-atorylate having a dry weight of 50 wt. The dry mixture containing 100 wt. parts of cement (SPC 250), 280 wt. parts by weight of siliceous grit with a grain size of 0.1 to 0.5 mm and 3 wt. 35 parts by weight of carbonic acid diamide are added. parts of water and 5 wt. parts of the additive. The mixture has a consistency of 16.8 with VEBE, a pourability of 49 cm and a solidification of 0.3 wt. The mixture without additive has a consistency of 28.3 with VEBE, a pourability of 37 cm and a solidification of 2.6 wt. The mixture is used as a sealant for sealing cracks in concrete or stoneware substrates.

Example 4

The cement modification mixture is prepared from 20 wt. % by weight of polyvinyl alcohol having a dry weight of 25 wt.%, 10 wt. parts of triethanolamine and 70 wt. % by weight of an aqueous dispersion of styrene-2-ethylhexyl acrylate-acrylic acid with a dry weight of 50 wt. 6 wt. parts are added to 27 parts water. The solution is used as a mixing water for a 100 wt. parts of white cement (PC 450), 250 wt. parts of silica flour, wt. parts of calcium stearate. 8 wt. parts of mtoomyl or asbestos and 0.1 wt. parts of calcium lignosulfonate. The mixture has a consistency of 13.2 with VEBE, a spillage of 57 cm and a solidification of 0.5 wt. The mixture without additives has a consistency of 28.3 with VEBE, a pourability of 37 cm and a solidification of 2.6 wt. The mixture is used as a paint for an aggressive environment.

Claims (1)

SUBJECT An additive for plasticizing and controlling the solidification of cement, characterized in that it contains, on a dry weight basis, 0.1 to 19.9 parts by weight of polyvinyl alcohol, 0.05 to 4.95 parts by weight of triethanolamine, or 3 to 18 parts by weight. INVENTION parts by weight of an aqueous dispersion of macromolecular substances or redispersible polymers based on polymers or copolymers of vinyl acetate, acrylic acid, alkyl acrylates and styrene.