In the January issue of Concrete Construction, articles from Scott Tarr, president of North S.Tarr Concrete Consulting, and George Garber, with Face Consultants, described the uses of and expectations for liquid surface hardeners used on concrete floors. With Garber concluding that liquid hardeners are ineffective at increasing wear resistance and Tarr insisting that although silicate hardeners improve concrete surfaces they should not be used for curing or for moisture mitigation.

To give the hardeners industry a chance to respond, we talked with Peter Wagner, managing director of Wagner Innovations, who has been involved with polished concrete and surface hardeners for many years. He described how densifiers have been used for concrete floors and how silicates combine with alkalinity to increase wear resistance and protect the surface. He showed several densified floors that have been in service for over 10 years with little sign of wear. He defended the validity of manufacturer testing that indicates significant increase in wear resistance of polished and hardened floors. He concluded that liquid silicate floor hardeners provide a significant benefit to concrete floors, especially polished floors.

Garber conceded that there may be cases where liquid silicate hardeners will improve floors. He stated, however, that the floors he has tested did not show significant improvement and that these materials are not needed for properly finished and cured concrete floors but that they may be a remedy for defective work. He is skeptical of manufacturer claims and reiterated that in six floors he has tested where there was a control (untreated) slab, he could not show significant improvement, leading to the conclusion that silicate hardeners either don’t work or don’t work consistently.

Watch the full debate here.