Estudo da reologia de betões activados alcalinamente com escórias de alto forno.

November 27, 2026

In this dissertation, the rheology of alkali-activated materials based on blast furnace slag was evaluated, studying the effect of the Na2O/precursor ratio, the modulus Ms, and the type and dosage of plasticizer. Na2O/precursor ratios of 13% and 10%, by precursor mass, Ms modulus (mass ratio SiO2/Na2O) of 0,5 and 1,0, and five different plasticizers were used. Na2SiO3 and NaOH were used as activators. The experimental campaign was organised in three phases, being the first one relative to the rheological study of pastes, the second on the rheological study of mortars, and the third on the study of the fresh and hardened state of concretes. The compositions with the best results in the paste phase were those with lower Na2O/precursor contents. Reducing the Ms ratio improved rheological behaviour in the paste and mortar phases, except for the composition 13/0,5 (Na2O/precursor = 13% and Ms = 0,5). In the concrete phase, the 13/1 exhibited better overall results For the 13/1 mixes, the plasticizers Mapetard and Sika Plastiment VZ provided greater workability, for the 10/1 and 10/0,5, Mapetard performed better, and for the 13/0,5 compositions, MasterSet R111 performed better. Regarding setting time, MasterSet R111 contributed to an overall delay, except for the 13/0,5 mixes, where Mapetard and Sika Plastiment VZ were more effective. It is concluded that the combined control of the analyzed parameters is crucial for designing these mixes, ensuring suitable performance in both the fresh and hardened states.

Authors in the community:

• 

  J

  João Miguel Saraiva Soares

  ist189907

Supervisors of this institution:

• 

  J

  Jorge Manuel Caliço Lopes de Brito

  ist12299

• 

  M

  Miguel Nuno Caneiras Bravo

  ist154930

civil-engineering - Civil engineering

por - Portuguese

Instituto Superior Técnico