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Limestone powder and silica fume performance on slag‑blended PLC plain and self‑consolidating mortars properties

Chiker Tarek, Aggoun Salima

Archives of Civil and Mechanical Engineering

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2024

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Vol. 24, no. 1

art. no. e26, 2024

EN

Mineral admixtures and waste by-products in concrete exhibit economical and environmental benefits, but their cementing and engineering properties should be assessed before practical adoption. In this study, we investigated hydration and physical properties of Self-Consolidating (SCM) and Ordinary (OM) mortars, based on slag-blended Portland limestone cement (PLC), with equivalent water-to-cement ratio (E/C≈ 0.55). The variables were mortar type and mineral admixture type, limestone powder (LP) or silica fume (SF). Therefore, we made two ordinary mortars (OMs), Oref (OPC based) and Oplc (slag PLC based), and two self-consolidating mortars (SCMs), SplcL (limestone based) and SplcS (silica fume based). We assessed compressive strength, sorptivity, hydration heat, thermogravimetric analysis, and SEM images. Results reveal that Oplc exhibits similar to better performance than Oref; blended LP leads to 36% higher mechanical strength, more than 50% carboaluminate in SCMs, and 40% lower heat and rate of hydration, and seems to have packing role and doesn't contribute to more sites’ nucleation; SF is efficient when substituted more than 10%.

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Comparative study on externally bonded heat‑treated jute and glass fiber reinforcement for repair of pre-cracked high performance concrete beams

Benaddache Lysa, Belkadi Ahmed Abderraouf, Kessal Oussama, Berkouche Amirouche, Noui Ammar, Aggoun Salima, Chiker Tarek, Tayebi Tahar

Archives of Civil and Mechanical Engineering

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2024

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Vol. 24, no. 2

art. no. e82, 2024

EN

The adoption of natural fiber reinforced polymer (FRP) composites as an eco-friendly substitute for synthetic FRPs in structural strengthening applications is gaining substantial momentum. This study delves into the effectiveness of jute fabric reinforced epoxy composites in bolstering the flexural strength of impaired concrete beams. An array of variables, encompassing the number of fabric layers (ranging from 1 to 3), fiber heat treatment, externally bonded reinforcement (EBR) configuration (soffit vs. U-shape), and fiber type (jute vs. glass), underwent systematic scrutiny. The comprehensive analysis of 30 pre-cracked high-performance concrete beams yielded compelling findings. In particular, the application of heat-treated jute EBR, especially when employing two or three layers, resulted in significant increases in peak loads, translating to improvements ranging from 85 to 120% when compared to the control beam. This treatment significantly improves the bond between the fibers and the matrix, consequently enhancing the structural performance. Notably, jute composites can attain equivalent strengthening performance compared to glass FRP while offering substantial cost savings and significantly reducing carbon emissions, rendering them a more environmentally sustainable and economically viable choice.

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Aggregate Type Influence on Microstructural Behavior of Concrete Exposed to Elevated Temperature

Belkadi Ahmed Abderraouf, Kessal Oussama, Bensalem Sara, Aggoun Salima, Amouri Chahinez, Khouadjia Mohamed Lyes Kamel

Civil and Environmental Engineering Reports

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2022

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Vol. 32, no. 1

19--42

EN

Exposure of concrete to high temperatures affects its mechanical properties by reducing the compressive strength, bending… etc. Factors reducing these properties have been focused on by several studies over the years, producing conflicting results. This article interested an important factor, that is the type of aggregates. For this, an experimental study on the behavior of concrete based on different types of aggregates: calcareous, siliceous and silico-calcareous subjected to high temperatures. In addition, the particle size distribution of the aggregates was chosen to be almost identical so that the latter does not affect the behavior of the concrete. Aggregates and concrete samples were subjected to a heating/cooling cycle of 300, 600 and 800°C at a speed of 1°C/ min. The mechanical and physical properties of concrete before and after exposure to high temperatures were studied. In addition, a microstructural study using a scanning electron microscope and a mercury porosimeter was performed. Thus, a comparative study between various researches on the mechanical properties of concrete exposed to high temperatures containing different types of aggregates was carried out. The compressive strength test results showed that the concrete based on siliceous aggregates (C-S) has better mechanical performance up to 300°C. However, above 300°C, the compressive strength decreases faster compared to calcareous-based concrete (C-C). According to the mercury porosimeter test, at 600°C, C-SC and C-S concretes have the highest number of pores compared to C-C concretes. The microstructure of concrete at high temperatures was influenced mainly by the aggregate’s types and the paste-aggregate transition zone. This study reinforces the importance of standardizing test procedures related to the properties of concrete in a fire situation so that all the results obtained are reproducible and applicable in other research.