Batimix VMA 520-S

Holderchem

Viscosity modifier with plasticizing effect for highly flowable concrete

Description

BATIMIX VMA 520-S is a ready-to-use liquid admixture designed to modify the viscosity of fresh concrete. It is blended with polycarboxylate-acid polymers to ensure concrete workability is not significantly reduced.

Main Purpose

BATIMIX VMA 520-S enhances the cohesiveness of highly flowable concrete. It reduces the risk of material separation during casting and until the onset of hardening. Its water-soluble polymers are characterized by their long-chains of complex forms that adhere to the periphery of mixing water molecules in a cement paste. The chains can intertwine and develop attractive forces through hydrogen bonds and polymer entanglements, resulting in increased plastic viscosity and yield stress even in mixtures with high water-cement ratios. Applications include all types of plain and reinforced concrete castings such as highly flowable concrete, self-consolidating concrete, and shotcrete.

Features

Concrete prepared with BATIMIX VMA 520-S is characterized by the following:

In the plastic state:

  • Greatly reduced bleeding and segregation
  • Increased cohesiveness with fewer risks to of mixture constituents separating
  • Enhanced level of slump retention over time
  • Improved stability of fresh concrete during casting and thereafter
  • Thixotropic action, providing enhanced homogeneity
  • Sag-resistance in shotcrete applications
  • When used along with a superplasticizer in a highly flowable self-consolidating concrete, vibration may be eliminated

In the hardened state:

  • At normal dosages, no detrimental effect on setting time
  • Improved durability and better surface quality

Properties

  • Appearance : brown liquid
  • Specific gravity : around 1.04 at 23 ºC
  • Chloride content : nil
  • Alkali content : typically less than 1% as Na₂O
  • Air entrainment : less than 1.5% increase at normal dosages

Compliance with Standards

BATIMIX VMA 520-S complies with EN 934-2:T4 and BS 8443:2005 requirements.

Dosage Rates

BATIMIX VMA 520-S may or may not be used in conjunction with a superplasticizer, depending on the desired level of workability and cohesiveness. Its optimum dosage and its effect on the fresh concrete properties such as workability, bleeding, segregation, and slump retention is best determined by trials using the actual mix composition with site materials under field conditions. As a guide to such trials, the addition rates shall vary from 0.4% to 1.2% of the cementitious materials.

Effect of overdosing

An overdose of BATIMIX VMA 520-S will result in highly sticky and viscous material requiring significantly higher dosages of superplasticizer to ensure concrete workability. This, in its turn, will delay setting times and decrease strength development especially after 24 hours. Provided adequate curing is applied, the ultimate strength will not be impaired by such setting retardation.

Compatibility

BATIMIX VMA 520-S is compatible with all types of plasticizers wether based on lignosulphonate, naphthalene sulphonate, or polycarboxylate-acid. It should not be pre-mixed with other admixture as this may alter its performance. During batching, the admixtures should be added separately to the concrete mix. The performance of various admixtures on the fresh and hardened concrete properties should be assessed using trial tests.

BATIMIX VMA 520-S is compatible with all types of Portland cement and replacement materials such as silica fume, fly ash, and blast furnace slag.

Dispensing

Accurate and reliable automatic dispensing systems should be used to introduce the correct quantity of BATIMIX VMA 520-S in the concrete mixer. This product should not be directly added on the dry cementitious particles. It should rather be introduced towards the end of mixing, i.e. after incorporating all of the mixing water and other chemical admixtures.

Typical batching sequence that may be used when producing highly-flowable self-consolidating concrete with BATIMIX VMA 520-S is as follows: • air entraining admixture (optional) • set-modifying admixture (optional) • high-range water reducer • BATIMIX VMA 520-S

Technical Support

Holderchem provides, upon request, complete technical support and on-site assistance to enable correct and effective use of its products.

Storage

BATIMIX VMA 520-S has a minimum shelf life of 12 months if kept unopened and stored at temperatures ranging from 2 to 50 ºC.

Packages

  • 1 t IBC
  • 200 kg metallic drum
  • 20 kg metallic pail
  • 4 kg metallic pail
TS 5539Issue Date: 10-01-2021

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