If the admixtures you are using do not improve the fluidity of cement, please pay attention to these cement admixtures.
Water-reducing agent can improve the fluidity of cement mortar under the condition of low water-cement ratio, reduce the water consumption for mixing without reducing fluidity, improve the compactness of cement hardening body structure and improve mechanical properties.Type of water reducer has a great impact on self-leveling mortar, polycarboxylic acid series water reducer is the third generation of water reducer developed after naphthalene series and melamine series water reducer, compared with the first two generations of water reducer, it has the advantages of low dosage, high water reduction rate, good liquidity retention ability, strong adaptability and so on.But the superplasticizer dosage is too much, not only can not improve the fluidity, but will lead to mortar segregation and bleeding.
2. Water-retaining Agent
The water retaining agent can give the mortar thixotropic consistency, reduce the evaporation and absorption of water, which is beneficial to extend the operating time and improve the stability.Water retaining agent is a kind of three-dimensional network structure of high polymer, there are many hydrophilic groups in the crosslinked network structure, which can combine with water molecules to form hydrogen bonds, and absorb a large amount of water.The water-retaining agent used in cement mortar is cellulose ether, mainly including methyl hydroxyethyl cellulose ether (MHEC), methyl hydroxypropyl cellulose ether (MHPC) and methyl cellulose ether (MC).The water retention and consistency of the slurry will change with the addition amount, viscosity and fineness of cellulose ether.
3.Redispersible latex powder
Redispersible latex powder can effectively improve its cement mortar tensile bond strength, wear resistance, toughness, anti-permeability, improve liquidity, stability and volume shrinkage also has a certain effect.Commonly used are vinyl acetate and vinyl copolymer powder, vinyl chloride and vinyl laurate copolymer powder, vinyl acetate and vinyl and higher fatty acid vinyl ester copolymer powder.After the re-dispersible emulsion powder is mixed into cement, the emulsion is formed in water and evenly distributed in the cement slurry. The polymer dispersion forms a film on the surface of the hydrate and finally forms a continuous polymer network structure.The cross - linking and permeation of hydrate and thin film improve the structure of the slurry.When the cement body is stressed, the polymer network can effectively absorb and transfer energy, thus inhibiting the formation and expansion of cracks.
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