VEGETABLE RESIDUE AND PORTLAND CEMENT CHEMICAL COMPATIBILITY BY ULTRASONIC PULSE VELOCITY (UPV)

Inhibitory substances present in vegetable residues can strongly affect the kinetics of the hydration reactions of Portland cement compounds. Earlier researches concerning the knowledge of the chemical compatibility between vegetable residues and inorganic binder were carried out by means of a hydration curve. The parameters evaluated include maximum temperature and time elapsed, maximum slope of the hydration curve and the area below the curve. Besides, the composite hydration curve was compared to the cement paste curve. In this research work it was proposed an alternative method of investigating vegetable residues and Portland cement compatibility. Setting and hardening of cement paste and several vegetable residues, combined or not with catalyst, were daily monitored by ultrasonic pulse velocity (UPV). Mathematic models showed the sensibility of that method in detecting deleterious effects caused by a non compatible vegetable residue on cement structure and the influence of the cement type as well as the catalyst on the composite performance.