LUDOX® Colloidal Silica - A Versatile Tool for Building & Construction
The demand for resilient products from consumers of building materials has increased drastically over the last decade. In order to stay competitive, producers of building materials like concrete, coatings, adhesives, and sealants need to innovate to improve resiliency of their products while also reducing costs. Formulating with LUDOX® colloidal silica provides end products with improved strength and consistency that boost productivity and reduce cost.
Shotcrete & Sprayable Concrete
Traditionally silica fume has been used as a pozzolanic rheology 
modifier and binder in sprayable concrete. LUDOX® colloidal silica offers a number of benefit over silica fume when used as a concrete bonding agent. LUDOX® densifies concrete and imparts shotcrete with better cohesive strength than silica fume thus improving sprayability, increasing layer thickness, and reducing rebound. LUDOX® also reduces setting time when compared to silica fume due to a higher surface area and faster hydration. Because it is an aqueous dispersion, LUDOX® can be easily dispersed in concrete without generating any hazardous dust and reduces mixing time and the risk of agglomeration.
modifier and binder in sprayable concrete. LUDOX® colloidal silica offers a number of benefit over silica fume when used as a concrete bonding agent. LUDOX® densifies concrete and imparts shotcrete with better cohesive strength than silica fume thus improving sprayability, increasing layer thickness, and reducing rebound. LUDOX® also reduces setting time when compared to silica fume due to a higher surface area and faster hydration. Because it is an aqueous dispersion, LUDOX® can be easily dispersed in concrete without generating any hazardous dust and reduces mixing time and the risk of agglomeration.Concrete Sealer and Paint
LUDOX® colloidal silica can be easily added to water based formulations to improve resilience and anti-soil properties. Silicate based paints and sealers provide outstanding adhesion to masonry and cementitious surfaces. LUDOX® can be used as an additive to silicate based coatings to improve the rate of cure and the development of water resistance. Lithium polysilicate from Grace can also be used in cement coating applications as a co-binder with potassium silicate to improve surface density and chemical resistance.Anticorrosive Pre-Treatment
Chromium based coatings are commonly used to protect metals
from corrosion. More recently, hexavalent chromium formulations are being phased out due to regulatory concerns. LUDOX® helps to improve the adsorption of trivalent chromium and promote film formation. In addition, the high surface area of LUDOX® helps to control the rheology of the coating. Zinc-rich primers are typically used in marine environments to protect steel used for structural purposes due to the weather and chemical resistance they provide. Grace's Lithium Polysilicate exhibit outstanding compatibility with zinc powder and can be used as a binder and vehicle for zinc-rich primers.Caulks & Adhesives
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® will bind to other silica and inorganics in caulks and adhesives to provide reinforcement, added strength, and improved water and chemical resistance. In addition LUDOX® improves adhesion of caulks and sealants to metallic and other inorganic substrates.Formulation Guidance
LUDOX® colloidal silica vary mainly in particle size, silica content, stabilizing ion, pH, and surface charge. The smaller particle size grades are suited for binding application and the larger particle size grades are better for surface modification. Most grades are stabilized with sodium but there are ammonium stabilized grades available for applications where sodium poses an issue. Positively charged, chloride stabilized grades are also available for formulations with significant levels of cations. 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 |
| 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 |