logo-grace.pngLUDOX® Colloidal Silica: A Versatile Tool for Building and Construction

The demand for materials with better resiliency in the building and construction industry has increased drastically over the last decade. To stay competitive, producers of building materials such as concrete, coatings, adhesives, and sealants must innovate their processes to increase the resiliency of their products. Formulating with LUDOX® colloidal silica from Grace provides improved strength and consistency, boosts productivity, and reduces costs for end products used in the construction industry.

Shotcrete and Sprayable ConcreteShotcrete-260x260.jpg

Traditionally, silica fume has been used as a pozzolanic material added to sprayable concrete. LUDOX® colloidal silica offers several benefits over silica
fume when used as a concrete bonding agent. Silica fume particles are typically around 1 µm in diameter, significantly larger than the typical 5–22 nm range of LUDOX® silica particles. These smaller LUDOX® particles provide greater bonding capacity than silica fume, especially for smaller-sized cement particles and aggregate. Thus, LUDOX® imparts shotcrete with better cohesion than silica fume, improving sprayability, increasing layer thickness, and reducing rebound. LUDOX® also reduces setting time compared to silica fume due to its higher surface area. Since it is an aqueous dispersion, LUDOX® can be easily dispersed in concrete mixes, reducing mixing time and the risk of agglomeration without creating hazardous dust.

Concrete Sealer and Paint

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LUDOX® colloidal silica can be easily added to water-based formulations to improve resilience and antisoiling properties. In latex paints, the silica particles of LUDOX® bind resins and other formulation components to create a cross-linked film that has better abrasion resistance and durability. Paints and sealers that incorporate LUDOX® also provide outstanding adhesion to masonry and cementitious surfaces, as silica forms strong bonds with inorganic materials. Additionally, LUDOX® can be used as an additive to silica-based coatings to improve the cure rate and water resistance.

Lithium polysilicate from Grace can also be used in cement coating and densifier applications with or without a potassium silicate cobinder to improve surface density, protect from corrosion, and increase cure speed. Grace's lithium polysilicate is a high-ratio silicate with a higher molar ratio of silica to metal oxide. A higher molar ratio of silica is essential to prevent deleterious aging effects in building applications.

Anticorrosion Coatingsshutterstock_1248240316.jpg

Chromium-based coatings are commonly used to protect materials like metals, concrete, and wood from corrosion in building and construction applications. Recently, however, hexavalent chromium formulations are being phased out due to regulatory concerns. As an alternative, trivalent chromium can be used for corrosion protection. LUDOX® can help to improve the adsorption of trivalent chromium, promote film formation, and improve rheology.

Zinc-rich primers are typically used in saltwater environments to protect steel against corrosion. Grace's lithium polysilicate exhibits outstanding compatibility with zinc powder and can be used as a binder and vehicle for zinc-rich primers. The high-ratio silicate property of lithium polysilicate mentioned in the previous section contributes to faster drying times, longer pot life, and better film-forming characteristics.

Caulks and Adhesivesshutterstock_716632522.jpg

Caulks and adhesives play a vital role in the long term  durability of a building.  Moisture damage can be costly and result in safety issues.  LUDOX®  particles will bind to other silica and inorganics in caulks and adhesives to provide reinforcement, added strength, and improved water and chemical resistance. LUDOX® also improves the adhesion of caulks and sealants to various materials commonly used in building components.

Formulation Guidance

LUDOX® colloidal silica varies in particle size, silica content, stabilizing counterion, pH, and surface charge. The smaller particle size grades are suited for binding applications, and the larger particle size grades are better for surface modification. Most grades are stabilized with sodium, but ammonium-stabilized grades are available for applications where sodium poses an issue. Positively charged, chloride-stabilized grades are also available for formulations with significant cation levels. Care should be taken to choose a LUDOX® grade that matches the pH of the formulation. Some commonly used grades and their specifications are listed below.

    Grade Surface Charge Silica Content Counter Ion Particle Size pH
    SM
    Negative
    30%
    Sodium
    7 nm
    10.0
    SM-AS
    Negative
    25%
    Ammonium
    7 nm
    9.5
    HS-30
    Negative
    30%
    Sodium
    12 nm
    9.7
    HS-40
    Negative
    40%
    Sodium
    12 nm
    9.7
    AS-40
    Negative
    40%
    Ammonium
    22 nm
    9.2
    TM-50
    Negative
    50%
    Sodium
    22 nm
    9
    CL
    Positive
    30%
    Chloride
    12 nm
    4
    Lithium Polysilicate
    Negative
    20%
    Lithium
    N/A
    11.0

Summary

LUDOX® colloidal silica and lithium polysilicate play essential roles in increasing the durability and resiliency of a range of materials used in building and construction. In concrete, the LUDOX® silica particles help to provide better cohesion and pozzolanic activity than silica fume. Also, concrete densifiers and coating formulations that include lithium polysilicate have faster cure times, better penetration, and greater adhesion to concrete and masonry. When LUDOX® is used in adhesives and sealants, it becomes more resistant to chemicals and has better adhesion to building surfaces.

ChemPoint is here to help you with your formulation process for building and construction applications. Click below to speak to a specialist about Grace LUDOX® and lithium polysilicate today.

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