Evaluation of an Alternative Flocculation System for Manufacture of Fiber−Cement Composites

Abstract

Flocculation has been a key issue for fiber cement manufacturing since cellulose or poly(vinyl alcohol) (PVA) fibers are used to replace asbestos. Due to the complexity of flocculation, many fiber cement companies face difficulties in optimizing it, which leads to unpredicted production problems and lower process efficiency. This paper studies the behavior of a dual system (PFR/PEO) and compares it with two anionic polyacrylamides commonly used in this industry. The work was carried out using a focused beam reflectance measurement as a sensor to monitor the flocculation process in real time. Results show that the proposed alternative dual system induces the formation of larger but less stable flocs than the ones obtained with the anionic polyacrylamides. A flocculation mechanism was proposed for the dual system consisting of the initial adsorption of the phenol−formaldehyde resin (PFR) onto the particles, which provides junction points for bridge formation by poly(ethylene oxide) (PEO). The flocculation kinetics induced by the dual system is determined by the PFR dosage.

Nanocelluloses: Natural-Based Materials for Fiber-Reinforced Cement Composites. A Critical Review

“…Negro et al [119] have shown that this effect is lower when the charge density of APAM increases and the molecular weight decreases. They have also proposed the use of alternative flocculants as dual systems formed by polyethylene oxide and phenolic resins [120,121].…”

Impact of polyacrylamide adsorption on flow through porous siliceous materials: State of the art, discussion and industrial concern

“…[5][6][7][8][9][10][11][12][13][14][15] They are also deployed in the construction materials industry in order to tailor the rheology of these materials at the fresh state during the casting process. [16][17][18][19][20] As already stated, another important example can be found in EOR, where PAM/HPAM are used as mobility control agents. In this case, the adsorption of polymer onto mineral surfaces leads to an erosion of the viscous front and affect the injectivity process.…”

Effect of polyacrylamide on rheology of fresh cement pastes

“…For instance, fiber cement composite production involves addition of PAM in order to tailor the flocculation properties to the casting process [1][2][3][4]. According to [5][6][7], PAM allows for an increase in the density of the resulting industrial product, which, in turn, is at the origin of an increase in mechanical strength.…”