Renolith™ is a patented polymer-based emulsion of latex, cellulose and nanoparticles. It is used as an additive to enhance soil-cement pavement construction and performance.

Renolith: Nanopolymer Admixture of the Future

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Renolith 2.0 nanopolymer admixture is a latex polymer dispersion with nanoscale cellulose and silicon dioxide.

Definitions

  • Nanopolymer admixture – a polymer-based admixture containing nanoscale ingredients.
  • Polymer – A long or larger molecule consisting of a chain or network of many repeating units, formed by chemically bonding together many identical or similar small molecules called monomers. A polymer is formed by polymerization, the joining of many monomer molecules.
  • Nanoparticle – Nanoparticles (NPs) are wide class of materials that include particulate substances, which have at least one dimension less than 100 nm.
  • Nanofibre – Nanofibres are fibres with diameters in the nanometer range (typically, between 1 nm and 1 μm).
  • Nanopolymer – Nanopolymer is a polymer or copolymer material containing dispersed nanoparticles.
  • Admixture (cement) – An admixture is a material other than water, aggregates, cementitious materials, and fibre reinforcement, used as an ingredient of a cementitious mixture to modify its freshly mixed, setting, or hardened properties and that is added to the batch before or during its mixing.

Latex

Latex (emulsion) Styrene Butadiene Rubber (SBR) is often used as part of cement-based substructural waterproofing systems. SBR aids the bond strength, reduces the potential for shrinkage and adds flexibility.

Latex based admixtures for mortars and concrete were first researched in the 1930s, became popular in the 1960s and are still in use today.

Cellulose

The use of fibres is a well-understood approach to improving cemented composites. Cellulose fibres help to:

  • suppress and stabilise cracks
  • improve compressive and flexural strength
  • improve impact and fracture toughness properties. 

Processed cellulose fibres provide a desirable balance between mechanical, physical, and durability characteristics when placed in a cement matrix. The improved reinforcing properties of processed cellulose fibres can be attributed to the suppression and stabilisation characteristics of the cracks. The high fibre count, large surface size, and high elastic modulus of the processed cellulose fibres are ideal for reinforcement efficiency. As the data have indicated, these fibres have a potential to improve compressive and flexural strength of concrete mixtures. Both normal-strength and high-strength concrete mixtures with fibres also have vastly improved impact and fracture toughness properties. Cellulose fibres have long been used in the building industry. It is about time that the transportation infrastructure industry, especially the paving industry, starts to profit from the beneficial properties of these processed cellulose fibres.

N. Buch, O. Rehman and J. E. Hiller, “Impact of Processed Cellulose Fibers on Portland Cement Concrete Properties,” Transportation Research Record Journal of the Transportation Research Board, pp. 72-80, 1999. https://doi.org/10.3141/1668-11

Fibres can be incorporated as part of the mix along with aggregate and cement. Or, in the case of Renolith, nanocellulose is part of the dispersion. Applied at the nano scale, cellulose imparts some additional interesting properties such as frost and salt resistance.

Nanocellulose, being a material with nanodimensions, is characterized by high tensile strength, high modulus of elasticity, low thermal expansion, and relatively low density, as well as exhibiting very good electrical conductivity properties. The paper presents the results of research on cement mortars with the addition of nanocrystals cellulose, applied in three different amounts (0.5%, 1.0%, and 1.5%) by weight of cement, including: physical and mechanical properties, frost resistance and resistance against the detrimental effect of salt, and microstructure examination (SEM). Along with an increase in amount of admixture, the weight loss following frost resistance and salt crystallization tests is reduced. Studies have shown that the addition of nanocrystalline cellulose improves the compressive and flexural strength by 27.6% and 10.9%, respectively. After 50 freezing and thawing (F–T) cycles for the mortars with 1.5% nanocellulose admixture, an improvement in frost resistance by 98% was observed. In turn, the sulfate crystallization tests indicated a 35-fold decrease in weight loss following 1.5% nanopolymer addition to the mortar.

D. Barnat-Hunek, M. Grzegorczyk-Franczak, M. Szymanska-Chargot and G. Łagód, “Effect of Eco-Friendly Cellulose Nanocrystals on Physical Properties of Cement Mortars,” Polymers, vol. 11, no. 2088, pp. 1-20, 2019. https://doi.org/10.3390/polym11122088

Nanoparticles in General

Nanoparticles improve the quantity and effectiveness of cementitious bonds.

Nanoparticles are highly efficient additives for modification of cement products, even at small concentrations (≤1%). These modifications were attributed to the unique reactivity of nanoparticles associated with their small size and large surface area. In general, these effects are attributed to three mechanisms:

  1. increased nucleation sites due to the nanoparticles’ high surface area that facilitates formation of Calcium silicate hydrates (C-S-H);
  2. formation of C-S-H via pozzolanic reaction of some silica-containing nanoparticles; and
  3. densification of cementitious materials via the filler effect. 

Reches, “Nanoparticles as concrete additives: Review and perspectives,” Construction and Building Materials, vol. 175, pp. 483-495, 2018. https://doi.org/10.1016/j.conbuildmat.2018.04.214

Not All Nanoparticles are Created Equal

Renolith contains non-agglomerating nanosilica with a very high specific surface area. This nanosilica is extremely potent in cemented materials and has enabled some other technological breakthroughs such as high strength nano-engineered concrete and the use of smooth desert sands as aggregate in concrete.

Many concrete additives on the market using ‘nanoparticles’ are made from silica dust; spherical particles of amorphous silicon dioxide with diameter less than 1µm (1000nm) and specific surface area of 15 to 35m2/g.

Nanosilica used in Renolith 2.0™ admixture are made directly from quartz sand (SiO2) using a customized crushing process, achieving a specific surface area over 300m2/g. A hydrolysis-stable polymer dispersion acts as the carrier substance to stabilize the nanosilicate particles, avoiding any agglomeration.

Dispersed quartz flour in water completely precipitates in a few minutes. In comparison, Renolith nanosilica is self-stabilizing and stays dispersed for years due to the large surface area and special production process, which avoids the agglomeration that occurs with other powdery nano-scale materials. Agglomerated nanoparticles need high shear forces to be dispersed again. Insufficient dispersion leads to a significantly reduced active surface.

Nanopolymer Admixture
Nanoparticles in Cement Hydration Reaction
Renolith cement hydration reaction
Cement Hydration Reaction Under the Microscope
Renolith cement hydration reaction under the microscope

Images on the left show the cured material with cement only.

From the images on the right, we can see the impact that Renolith has on the microstructure. 

  • Cement hydration products are more numerous and well formed.
  • Gaps between soil grains are filled, reducing permeability and providing fewer vectors for deleterious substances such as sulfates and chlorides.
  • The composite has improved mechanical properties such as compressive strength, tensile strength, and modulus.
  • Susceptibility to cracking is greatly reduced.

Summary

We have defined ‘Nanopolymer admixture’ as a polymer-based admixture for cementitious binders that includes nanoscale materials. Renolith 2.0 nanopolymer admixture is a latex polymer dispersion with nanoscale cellulose and silicon dioxide. The individual effects of these ingredients in cemented composites is well established in the technical literature, in summary:

Latex

  • Improved bond strength
  • reduces shrinkage
  • adds flexibility

Cellulose/Nanocellulose

  • suppress and stabilise cracks
  • improve compressive and flexural strength
  • improve impact and fracture toughness properties
  • Frost resistance
  • Salt resistance

Nanoparticles

  • increased nucleation sites
  • Improved formation of C-S-H via pozzolanic reaction
  • densification via the filler effect

The genius of Renolith is that it combines these synergistic ingredients into an easy-to-use and extremely effective admixture for cementitious binders. The cement hydration reaction yields improved density and strength of C-S-H & ettringite products with improved cross-linking and reduced voids.  Renolith 2.0 enables high-performing cementitious composites to be formed from nearly any in-situ or recycled material, including clays, silts, peats, contaminated and salty soils.

For more information, please visit our website.

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