Testing acrylics in Fiber Reinforced Cement (FRC) boards

July 3, 2023

A large set of additives can be used to improve cement-based materials, and this is the case for fiber reinforced cement (FRC) boards. However, the industrial process of making FRC boards (Hatscheck process) includes a filtration step. Therefore, there is a need to rely on some physic-chemical process to retain the additives in the boards despite the filtration and this could be made by increasing interaction between cement particles and additive particles. If the interactions are strong enough, this could indicate that the additive would not be flushed away with water during the vacuum filtration. A viscosity test was designed to assess interaction between cement particles and polymer additives. A large increase of cement paste viscosity was achieved with dispersions having polymer particles of low glass transition temperature (Tg) and higher content of acrylamide (AM) functional monomer, suggesting that these characteristics increase the most the interaction between polymer and cement particles. Testing the same samples in the centrifugation test corroborated the viscosity results. Water resistance of reference and modified FRC boards was tested. The board modified with silicone dispersion reduced the most the water absorption by capillarity and immersion. Efflorescence onset was observed in FRC boards treated with acrylic dispersions but not in boards modified with mixtures of silicone and acrylic. As such, it is most likely that a combination of silicone and acrylic dispersion maximizes the protection in the board against water penetration.

Authors in the community:

• 

  M

  Maria Carolina De Azevedo e Cunha

  ist188039

Supervisors of this institution:

• 

  A

  Ana Clara Lopes Marques

  ist45873

chemical-engineering - Chemical engineering

por - Portuguese

Instituto Superior Técnico