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Traditionally, the utilization of granulated blast-furnace slag (BFS) is based on activation with alkalies released from the hydration of portland cements (PC). In Finland, a special type of alkaline admixture was introduced some years ago for activation of BFS. In the present paper, some experiences based on the activation of a Norwegian BFS with this admixture are reported. To investigate the hydraulicity of the slag, the slag was ground to three different levels of Blaine fineness (420, 540, and 640 mý/kg) and hydrated at five different levels of curing temperature (20 to 60 C). For comparison, a Finnish slag and a Norwegian blended portland cement with 10 percent fly ash were also included in the test program. The test results demonstrate that increasing curing temperature and fineness of the slag significantly accelerate the strength development (more so at early ages than later on). Thus, at 60 C the slag with 640 mý/kg of fineness and a water-cement ratio of 0.33 reached a compressive strength of approximately 40 MPa after a curing period of 4 hr. After a curing period of 72 hr, the heat of hydration of the slag cements was only about 60 percent of that of the modified portland cement.

Presents results of research work on the evaluation of physical-chemical properties of fly ashes and their influence on physical and mechanical properties of cement mortars. Two types of fly ash were examined: a low-calcium and a high-calcium. Variability of chemical composition with grain size of the fly ashes was analyzed. When testing the influence of physical and mechanical activation (fly ash grinding process) on hydraulic activity of the two types of fly ash, it was found that grinding had an activating effect on the high-calcium fly ash. Consequently, cements containing ground high-calcium fly ash were comparable in strength to pure portland cement. The main factor affecting strength properties was the formation of ettringite and its stabilization in the structure of hardened mortars and pastes.

Presents the latest publications dealing with the development and practical application of activated slag clinker-free concretes with special reference to less known papers and recent information. The finely ground slag, usually granulated blast furnace slag, is activated by the solution of sodium or potassium hydroxide, carbonate, or preferably silicate (soluble glass) of appropriate concentration and silicate modulus. The difference of microstructure between portland cement concrete and alkali-activated slag concrete and its consequences for their properties, especially for very high strengths and corrosion resistance, is discussed. The use of nonstandard aggregate and other industrial by-products, as well as the low costs of this type of concrete are presented. Examples of applications of alkali-activated slag concrete of different composition are given. Some problems connected with the present use of alkali-activated concrete are discussed together with the most promising applications for the future.

Hydration of cements containing the supplementary cementing materials fly ash (FA) and silica fume (SF) is discussed and compared with the hydration of ordinary portland cement (OPC). Early stage heats of hydration, changes in the chemistry of the solution (both at early stages, and later pore solution compositions), microstructural development, and pore structure are compared. The hydration rates normally follow the order: SF > OPC > FA. The complex hydration processes may be controlled so that the use of these cements enables development of materials having superior strength and durability.

The chemical resistance of alkali-activated slag pastes and mortars in chloride solutions was studied. The four basic slag-alkali binding materials were prepared using granulated blast furnace slag, copper slag, and a mix of both these components. NaOH and Na?2CO?3 were used as activators. Some pastes and mortars containing 10 percent active silica additive were also made. The mortars were cured in standard conditions as well as subjected to low-pressure steam curing. The chemical resistance of alkali-activated slag mortars was compared with the chemical resistance of OPC mortars. The water-to-solid ratio was kept constant at 0.40. The samples cured in water were considered as reference samples. It has been found that the alkali-activated slag binders are chemical resistant in chloride solutions. These results were found not only from chemical resistance in chloride solutions and compressive and flexural strength tests, but also from the SEM observations of microstructure. The difference between the chemical resistance of slag and OPC mortars is probably the consequence of phase composition and porosity of the hydration products