Abstract
The identification on alkali-aggregated reactions in foundations of conventional structures in the beginning of the 21ST Century has led to the study of new ways to mitigate it. The first countermeasures suggested un the 1940s by Stanton, who was the first researcher to mention its occurrence, propose the use of low alkali cement (<0.60%) and the addition of pozzolans to the cement. Nowadays, the addition of fly ashes blast furnace slag, rice husk ashes, microsilica and metakaolim to the concrete has been a successful procedure. These materials are known as active additions or supplementary cement materials (SCM). A new line of research has been studying the use of reactive aggregated powders (RAP). This trend is based on the principle that, the more reactive the coarse aggregate is, the more efficient its powder will become, to fight alkali-aggregated reactions. In this context, this study evaluates the potential of basalt fine powder as a mitigation agent alkali-silica reactions. Powdery material collected from two samples of rocks from natural deposits in northern Paraná was micronizes and used to partially substitute Portland Cement type CPV ARI in three distinct volumes (30%, 45% and 60%). The efficiency of this material was evaluated through accelerated mortar bar tests. The result has indicated that basalt fine powder is efficient in reducing bar expansion, even though it has presented low levels of pozzolanic activity.
Reference
FILLA, J.C.; MORALES, G.; QUARCIONI, Valdecir Angelo. Aplicação do pó reativo de basalto na mitigação da reação álcali-sílica. In: CONGRESSO BRASILEIRO DO CONCRETO, 54., 2012, Maceió. Anais… São Paulo: IBRACON, 2012. 16p.
The identification on alkali-aggregated reactions in foundations of conventional structures in the beginning of the 21ST Century has led to the study of new ways to mitigate it. The first countermeasures suggested un the 1940s by Stanton, who was the first researcher to mention its occurrence, propose the use of low alkali cement (<0.60%) and the addition of pozzolans to the cement. Nowadays, the addition of fly ashes blast furnace slag, rice husk ashes, microsilica and metakaolim to the concrete has been a successful procedure. These materials are known as active additions or supplementary cement materials (SCM). A new line of research has been studying the use of reactive aggregated powders (RAP). This trend is based on the principle that, the more reactive the coarse aggregate is, the more efficient its powder will become, to fight alkali-aggregated reactions. In this context, this study evaluates the potential of basalt fine powder as a mitigation agent alkali-silica reactions. Powdery material collected from two samples of rocks from natural deposits in northern Paraná was micronizes and used to partially substitute Portland Cement type CPV ARI in three distinct volumes (30%, 45% and 60%). The efficiency of this material was evaluated through accelerated mortar bar tests. The result has indicated that basalt fine powder is efficient in reducing bar expansion, even though it has presented low levels of pozzolanic activity.
Reference
FILLA, J.C.; MORALES, G.; QUARCIONI, Valdecir Angelo. Aplicação do pó reativo de basalto na mitigação da reação álcali-sílica. In: CONGRESSO BRASILEIRO DO CONCRETO, 54., 2012, Maceió. Anais… São Paulo: IBRACON, 2012. 16p.
