Łukasz Kotwica

Effect of Metakaolinite on Properties of Alkali Activated Slag Materials

Metakaolinite was introduced to alkali activated slag mortars and pastes. Properties of fresh and hardened mortars as well as phase composition and microstructure of hardened pastes were investigated. Introduction of metakaolinite both as addition as well as substitution of slag results in severe decrease in strength of the mortars. SEM observations revealed, that metakaolinite presence results in much less compacted microstructure comparing to reference slag paste. The reason for that are differences in phase composition as determined with XRD. C-S-H phase formation is retained in the presence of metakaolinite and thus degree of hydration of slag is decreased comparing to reference, slag paste.

Influence of Sulphides on Hydration of Ground Granulated Slag Alkali Activated Mortars and Pastes

Influence of sodium sulphide on properties of sodium hydroxide activated ground granulated blast furnace slag was investigated. Properties of both fresh (cone flow, density) as well as hardened (compressive strength) mortars were determined. Early hydration of pastes was investigated using conducting calorimetry. Results showed, that introduction of sodium sulphide to caustic soda activated slag only slightly influence the course of hydration process. Early strength is increased by about 10%. In later periods strength is virtually not affected by the presence of sodium sulphide. Those observations are confirmed by calorimetric results. Presence of sodium sulphide causes slight decrease in consistency of mortars. Colour of mortars is also affected by the presence of sulphides. It is more darker and it is most probably due to the reducing properties of sulphide ions. Results of model investigations on precipitated C-S-H phase showed, that presence of sulphides results in increased main basal spacing of C-S-H phase as determined by XRD.

Influence of Calcined Mine Tailings on the Properties of Alkali Activated Slag Mortars

Influence of copper mine tailings on properties of soda activated ground granulated blast furnace slag mortars and pastes was investigated. Calcination of copper mine tailings was found to be a method of increasing their pozzolanic activity. Material calcined at 750°C possessed highest pozzolanic activity. So obtained material can be used as a partial substitution of ground granulated slag in soda activated blends. Introduction of calcined copper mine tailings decrease strength up to 28 days, but after 56 days strength results are similar or even higher comparing to control samples. Phase composition of hydrated material is not affected significantly by the presence of calcined copper mine tailings.

The Influence of Waste Expanded Perlite on Chemical Durability of Mortars

Degradation of building materials is an important phenomena influencing its design and utilization. Corrosion of concrete, due to common use of this material is especially important. Chemical corrosion of cementitous materials may be mitigated using various methods. Among them introduction of properly chosen active supplementary cementitous materials to the mix is one of most commonly used. One of possible additives possessing pozzolanic properties is ground waste expanded perlite. No data on the influence of such perlite on chemical durability of cementitous materials can be found in literature. Present paper presents results of investigation on the influence of ground waste expanded perlite on chemical durability of cement mortars. Results obtained showed that there is an improvement of durability of mortars modified with ground waste expanded perlite in sodium sulfate enviroment.