Toufik Boubekeur | Centre Universitaire de Tissemsilt (original) (raw)

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Papers by Toufik Boubekeur

HAL (Le Centre pour la Communication Scientifique Directe), Nov 12, 2019

The deterioration of self-compacting concretes (SCC) in acid and sulphate media is a major proble... more The deterioration of self-compacting concretes (SCC) in acid and sulphate media is a major problem in the evaluation of structural durability. The aim of our work is to study this effect and to do this, a test protocol was used to evaluate the effect of sulphate and acidic media on the mechanical properties and microstructure of SCCs. Two types of cement were used CEMIII-A-42.5 cement (60% slag) and cement CEMI-52.5 and three water / binder ratios (E / L = 0.32-0.38-0.44). The SCC specimens were stored in all three media, water (control), 5% H2SO4 and 5% Na2SO4. The measured properties were: The compressive strength of cubic test pieces at 30, 90 and 180 days and X-ray diffraction (XRD) analysis. These results show that high furnace slag improves the durability of SCCs.

International Journal of Engineering Research in Africa

This paper studies the effects of fine waste glass powder content (WGP) on fresh and hardened pro... more This paper studies the effects of fine waste glass powder content (WGP) on fresh and hardened properties of self-compacting repair mortar mixes (SCRMs). For this purpose, mortar mixes were prepared to replace cement with waste glass powder ranging from 0 to 30% at 10% interval and tested. Fresh properties were assessed using mini-slump flow and mini V-funnel. Hardened properties assessed for all mixes were water absorption (at 28-days of age), compressive and flexural strengths (at 7, 28 and 56-days of age). In addition, the adhesion between the repair mortar mixes and substrate was conducted using a 3-point flexural test on a composite prism (half mortar/half substrate) at 28 and 56-days of age. The results showed that glass powder had a negative effect on the workability of mortars. However, in the hardened state, it had a good influence on the strength development after 28 days, durability and adhesion of mortars with the substrate for a waste glass powder content not exceeding 20%.

This paper presents an experimental investigation for testing the effect of elevated temperature ... more This paper presents an experimental investigation for testing the effect of elevated temperature on the hydration heat and mechanical properties of blended cement mortars. Two tests on mortars were made. The first set of mortars is tested of mechanical properties at various temperatures of 20, 35 and 50°C and the second test consists to determine the hydration heat by a semi-adiabatic calorimeter at isothermal temperature of 20, 35 and 50°C during seven days. The new empirical equation has been proposed to estimate the compressive strength depending on the hydration heat for blended cement preserved in constant temperature at early. The results founded from this relationship illustrate a good accuracy with the experimental ones and reflect the best choice to be used to predict the compressive strength depending on the heat of hydration at early age (7 days)

L'étude de la cinétique de la chaleur d'hydratation apparaît comme un passage obligé pour... more L'étude de la cinétique de la chaleur d'hydratation apparaît comme un passage obligé pour comprendre les phénomènes physico-mécaniques qui contrôlent le comportement des matériaux cimentaires. Cette recherche est basée sur le suivi de l'évolution du degré d'hydratation pour un ciment ordinaire et ceux contenant 10% de calcaire, 20% de pouzzolane ou 30% du laitier sous des températures élevées. Les résultats obtenus permettent de mieux comprendre l'effet de la température de cure sur la cinétique d'hydratation et de comprendre la contribution des additions minérales sur l'amélioration des propriétés des ciments. Un nouveau modèle a été proposé pour la prévision des chaleurs dégagées des ciments composés sous des températures de cure constantes : ce dernier semble très puissant car il donne des coefficients de corrélation très proche de l'unité. Les écarts moyens entre les valeurs mesurées et calculées par le nouveau modèle ne dépasse pas 9, 11, 18, 14 ...

Resume La recherche actuelle sur les materiaux s’interesse au developpement de nouveaux composite... more Resume La recherche actuelle sur les materiaux s’interesse au developpement de nouveaux composites cimentaires, dans le but d’ameliorer les proprietes mecaniques, physiques et la durabilite des materiaux cimentaires, permettant de reduire la consommation d’energie, qui se traduit par la diminution du taux de gaz carbonique degage par les fours industriels. Le present travail porte sur l’effet de l’incorporation de deux ajouts cimentaires (le calcaire et le laitier) sur les proprietes physico-mecaniques et les performances de durabilite des ciments portland vis a vis des milieux agressifs telle que les sulfates et les acides. Les resultats montrent que l’addition de 10 % a 40 % de laitier au ciment contenant 10 % du calcaire diminue le pourcentage de la demande d’eau de 25.8 % a 24.8 % respectivement, De plus le temps de prise augmente avec l’accroissement du pourcentage du laitier. La substitution de 20 % a 40 % de ciment par du laitier dans un ciment Portland contenant 10 % de calc...

MATEC Web of Conferences, 2020

This paper presents the experimental results of a wide research program, tending to determine the... more This paper presents the experimental results of a wide research program, tending to determine the hydration mechanism, mechanical properties and the durability performance of ternary cement containing limestone powder and slag. The limestone powder increase the hydration at early ages inducing a high strength at, but it can reduce the later strength due to the dilution effect. On the other hands, Slag (S) contributes to increase the compressive strength at later ages. Hence, at medium blended cement (OPC-LP-S) with better performance could be produced. Results show at later age the Slag is very effective in producing ternary blended cements with similar on higher compressive strength than the ordinary Portland cement at 28 and 90 days. For durability, the incorporation of the slag into the cement containing limestone powder improves remarkably resistance to attack by acids and sulfates and it has been found that the durability of the cements never depends on the mechanical strength.

Journal of Adhesion Science and Technology, 2017

The study of the hydration kinetics appears as a prerequisite for understanding the physical and ... more The study of the hydration kinetics appears as a prerequisite for understanding the physical and mechanical phenomena that control the behavior of cementitious materials. This research is based on monitoring the evolution of the degree of hydration for ordinary cement and those containing 10% of limestone powder, 20% of natural pozzolana or 30% of the blast furnace slag under high temperatures. The results provide a better understanding the effect of cure temperature on the hydration kinetics and understand the contribution of mineral additions on improving the cement properties. A new model proposed gives the satisfaction results for predicting in later age the heat of hydration of cements blended kept under constant temperatures. The latter has a wider appreciation of the results, where it gives correlation coefficients very close of unity. This justifies the reliability of this new model proposed.

L'industrie des matériaux connaît un essor considérable en Algérie. La recherche actuelle sur les... more L'industrie des matériaux connaît un essor considérable en Algérie. La recherche actuelle sur les matériaux travaille sur le développement de nouveaux composites cimentaires, dans le but d'améliorer les propriétés mécaniques, physiques et la durabilité des matériaux cimentaires, ce qui permet de réduire la consommation d'énergie, qui se traduit par la diminution du taux de gaz carbonique dégagé par les fours industriels. Le présent travail porte sur l'effet de l'incorporation du laitier sur les résistances mécaniques des ciments à base du calcaire et les performances de durabilité vis à vis des milieux agressives telle que les sulfates et les acides. Les résultats montrent que l'ajout de 20 à 30 % de laitier améliore considérablement les propriétés mécaniques et la résistance aux agents chimiques des ciments composés par rapport au ciment de contrôle. ABSTRACT. The materials industry has expanded enormously in Algeria. Current research on materials worked on the development of new cementitious composites in order to improve the mechanical properties, physical and durability of cementitious materials, thereby reducing energy consumption, resulting in the decrease of the carbon dioxide rate released by industrial furnaces. This study focuses on the effect of the incorporation of slag on the mechanical strength of limestone cements and sustainability performance against aggressive environment such as sulfates and acids. The test results show that adding 20 to 30% slag significantly improves the mechanical properties and chemical resistance of blended cements with respect to cement control.

Construction and Building Materials, 2014

h i g h l i g h t s At early age, compressive strengths increase linearly with the curing tempera... more h i g h l i g h t s At early age, compressive strengths increase linearly with the curing temperature. At later age, mineral additions are activated and cause an increase in strength. With mineral addition; compressive strengths are less influenced by temperature rise. Compressive strength is predicted according to a new maturity index expression. The new maturity index provides the temperature effect on cement paste at later age.

Periodica Polytechnica Civil Engineering, 2022

This study highlights the effect of initial curing time on sustainability indicators such as sorp... more This study highlights the effect of initial curing time on sustainability indicators such as sorptivity (S), water absorption (WA) and total porosity (P) of self- compacting concretes (SCC) containing the blended cement such as limestone cement (CEMIIA-L42.5) and pozzolanic cement (CEMII-A-P42.5). The durability test (acid and sulfate attack) of SCCs is also studied in this researcher. For this purpose, three water/binder (W/B) ratios were used, Six SCC mixtures were prepared and tested in the fresh state (slump follow, flow time, J-Ring, L-Box, V-Funnel and sieve segregation), the main properties in the hardened state compressive strength (Sc), S, WA and P of the SCC mixtures were studied and evaluated each in its different curing. Furthermore, the results of the Sc and transfer properties are globally significantly affected by the hot climate during the design and maturation phase. On the other hand, the values of S to SCC for pozzolanic cement are lower compared to limestone ceme...

Construction and Building Materials, 2019