Evaluation of a flocculation dual system as a novel alternative for fiber-cement manufacture: Effect on product strength

The feasibility of using a dual retention system consisting on phenol–formaldehyde resin (PFR) and poly(ethylene oxide) (PEO) for fiber-cement manufacture was studied from the point of view of product properties. The effect of the dual system on fiber-cement properties was compared with the effect of a traditionally used anionic polyacrylamide (APAM), concluding that this dual system could be a good alternative to the traditional APAM. It improves considerably the product properties for all tried doses of PEO and PFR while an increase of APAM decreases product strength. The addition order of the components of the dual system and their doses were optimized. Doses of PEO and PFR lower than APAM ones allowed to improve fiber-cement properties, water removal during pressing and even retention, without significant effects on drainage rate.