Research Article
Influence of Sand Particle Size Distribution on the Properties of Mortars Subjected to Various Temperatures
Issue:
Volume 14, Issue 5, October 2025
Pages:
88-94
Received:
1 October 2025
Accepted:
16 October 2025
Published:
31 October 2025
DOI:
10.11648/j.am.20251405.11
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Abstract: The durability of concrete and mortar structures against extreme thermal stress is a major concern in Civil Engineering. This present experimental study aims to critically assess the influence of sand particle size distribution on the physico-mechanical and hydric characteristics of mortars after exposure to different temperatures. Cubic mortar specimens measuring 70 x 70 x 70 mm were manufactured using two types of sand (fine and coarse) of the same mineralogy, with a Sand/Cement ratio of 3 and a Water/Cement ratio of 0.5. The samples were subjected to five temperature levels: 20, 100, 150, 200, and 250°C. After cooling down to ambient temperature, several properties were measured, including mass loss, dimensional changes, bulk density, water absorption by immersion (total porosity), water absorption by capillarity, and compressive strengths. The results reveal a systematic influence of particle size: mortars made with fine sands exhibit a higher mass loss and consistently lower compressive strengths than those made with coarse sands, regardless of the applied temperature. In terms of hydric durability, fine sand mortars show lower water absorption by immersion (lower total porosity) but a higher absorption by capillarity, which indicates a microstructure characterized by finer but more interconnected pores, thereby favoring micro-cracking under thermal stress. In conclusion, the study demonstrates that sand particle size is a determining factor in the post-thermal performance of mortars, and the use of coarse sands is preferable to ensure better mechanical stability and increased resilience for structures exposed to temperatures up to 250°C.
Abstract: The durability of concrete and mortar structures against extreme thermal stress is a major concern in Civil Engineering. This present experimental study aims to critically assess the influence of sand particle size distribution on the physico-mechanical and hydric characteristics of mortars after exposure to different temperatures. Cubic mortar spe...
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Research Article
Investigation on Buffer Layers Influence on the Internal Quantum Efficiency of CH3NH3Sn(1-y)GeyI3 Lead-Free Perovskite-Based Solar Cells
Saliou Seck*
,
Alioune Sow,
Mamadou Salif Mane,
Modou Faye,
El Hadji Mamadou Keita,
Amadou Ndiaye,
Bachirou Ndiaye,
Babacar Mbow,
Cheikh Sene
Issue:
Volume 14, Issue 5, October 2025
Pages:
95-104
Received:
4 October 2025
Accepted:
18 October 2025
Published:
31 October 2025
DOI:
10.11648/j.am.20251405.12
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Abstract: In this work, we have carried out a study in the modeling of photovoltaic devices based on lead-free perovskite materials, such as CH3NH3Sn(1-y)GeyI3, in which the germanium content varies from 0 to 1, using thin ZnO, TiO2 or SnO2, films as window layers. Thin Cu2O or NiO layers used as buffer layers ensure the n-p junction with the perovskite absorber material and act as an interface layer with the transport window layer. With the above window and buffer layer materials, photovoltaic devices have been designed. The study highlights the influence of geometric parameters such as the diffusion length of the minority carriers in the buffer layer as well as the thickness of this layer on the performance of photovoltaic devices. The evolution of the internal quantum efficiency is analyzed as a function of the window and buffer layer materials and also as a function of various other parameters including the thickness of the buffer layer materials and the minority carrier diffusion length in these materials. The results showed that NiO thin films offer better performances, especially when combined with ZnO or SnO2 window layers, respectively. The corresponding models with structures ZnO(n+)/NiO(n)/CH3NH3Sn0.75Ge0.25I3(p) and SnO2(n+)/NiO(n)/CH3NH3Sn0.75Ge0.25I3(p) give an internal quantum efficiency of 72.7% and 70.9% respectively.
Abstract: In this work, we have carried out a study in the modeling of photovoltaic devices based on lead-free perovskite materials, such as CH3NH3Sn(1-y)GeyI3, in which the germanium content varies from 0 to 1, using thin ZnO, TiO2 or SnO2, films as window layers. Thin Cu2O or NiO layers used as buffer layers ensure the n-p junction with the perovskite abso...
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