As shown in Fig. 6, no significant differences were observed in relation to the compressive strength of the pastes after 28 days of hydration. They varied between 66.2 and 69.0MPa. Nondecrease in the compressive strength of RHA pastes is associated with the pozzolanic activity of this mineral admixture. Thus, based on the rheological and mechanical results, 20% RHA was the more effective content to improve s0 and a, maintaining the same 28-day compressive strength of the reference paste. In this research, improving the rheological parameters of the cement-based paste was a positive effect since the previous experiments in high work- ability concretes (slump over 200 mm) indicated a great tendency of segregation. Thus, high s0 and a in P-RHA20 indicated better cohesiveness for similar flowability.