Issue 59

O. Rahim et alii, Frattura ed Integrità Strutturale, 59 (2022) 344-358; DOI: 10.3221/IGF-ESIS.59.23

respectively for 20% and 50% replacement of cement by ground granulated blast furnace slag. This difference in permeability can be explained by the low hydraulic reactivity of the Algerian ground granulated blast furnace slag and therefore the period of 360 days of maturation was not sufficient for a good hydration of the studied slag and did not allow the densification of the microstructure necessary for improving permeability. However, for slags with good hydraulic reactivity, a better performance in permeability of concrete slag is reported at 28 and 90 days [15,16,24,38,40]. This proves both the low reactivity of the slag studied and the importance of wet curing for improving the durability of slag concretes.

C ONCLUSIONS

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n this article, the physical and mechanical properties of HPCs based on ternary binders formulated with granulated slag in partial substitution for cement are presented. We were able to demonstrate the value of replacing cement with granulated slag in the development of high performance concretes. Based on the results obtained, the following conclusions can be drawn: • Increasing the ground granulated blast furnace slag by 20 to 50% increased the workability of HPCs. This may be due to the smooth surfaces of the crushed granulated blast furnace slag. • At early and middle ages (up to 28 days), the addition of ground granulated blast furnace slag causes a decrease in compressive strength. However, after 360 days of curing, blends containing up to 30% ground granulated blast furnace slag showed an improvement in compressive strength. This is due to the latent hydration reaction of the ground granulated blast furnace slag. • The experimental results presented in this article confirmed that the addition of granulated blast furnace slag crushed (up to 30%) as a substitute for Portland cement can improve physical and mechanical properties of HPC based on ternary binder (cement, silica fume, and granulated blast furnace slag) with a compressive strength equal to 68.32 MPa at 28 days and 92.17 MPa at 360 days. As a result, the substitution up to 50% of cement is suitable for long-term mechanical properties (compressive strength equal to 80.412 MPa). • The use of ground granulated blast furnace slag with a low replacement rate (10 and 30) reduced the porosity of the water. However, the use of 50% granulated blast furnace slag as a replacement for cement slightly increased the porosity accessible to water. • The gas permeability coefficient increases with the increase in the replacement rate of crushed granulated slag from blast furnaces. The results obtained on the durability of high performance concrete are acceptable and stimulating compared to previous research of HPCs concrete [24,38,40,42]. • The results obtained show that it is possible to greatly limit the Portland cement content thanks to a granulated slag substitution rate of up to 50% in the manufacture of a new range of HPCs. This helps to reduce the emission of CO 2 into the atmosphere by reducing the energy required for the production of the non-additive cement used in the manufacture of HPCs which is very beneficial for the environment. A CKNOWLEDGMENTS he authors would like to thank Dr. Céline BASCOULÈS-PERLOT and the staff of laboratory SIAME - IPRA, EA458 of UPPA University (Anglet, France) who provided facilities for conducting the various durability tests in their laboratory.

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R EFERENCES

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