Disclosed are polymeric additives for concrete formed of a polyoxymethylene (POM) copolymer, POM copolymers can be utilized to form fibrous additives for concrete, i.e., microfibers and/or macrofibers. The POM copolymers can include one or more chemical groups, e.g., end groups and/or pendant groups that can increase the polarity of the POM and increase the hydrophilicity of the formed fibers, which can improve miscibility of the fibers in wet concrete. Chemical groups of the POM copolymers can bond with components of the concrete or can hydrolyze to form groups that can bond with components of the concrete, e.g., form covalent or noncovalent (e.g., electrostatic or ionic) bonds with one or more components of the concrete binder.