Salt Weathering in Anisotropic Calcarenite: Bedding-plane Controls on Sodium Chloride Precipitation Patterns

Mohammed Hraita — 2025-10-09

This study investigates the impact of bedding plane orientation on sodium chloride (NaCl) precipitation in a calcarenite stone, subjected to salt weathering cycles. It involves conducting wetting-drying cycles using sodium chloride on two series of specimens sampled parallel and perpendicular to the bedding plane. Capillary imbibition was carried out using saline solutions of two concentrations (15 g/L and 45 g/L). SEM observations show that, across all contaminated samples, halite precipitates mainly on the surface, in the form of efflorescence, while subflorescence remains negligible. The analysis identifies two distinct halite morphologies: (i) cubic crystals of 2 to 10 µm at grain boundaries and (ii) xenomorphic aggregates on pore walls, reflecting that the size and morphology of halite crystals vary according to local nucleation conditions, influenced by the mineralogical composition of the substrates and the degree of supersaturation reached during the cycles. X-ray diffraction analysis revealed significantly higher halite precipitation in samples oriented perpendicular to the sediment bedding (4.53–5.22%) than in those oriented parallel (2.71–4.17%), indicating that bedding plane orientation is a determining factor in weathering processes and the evolution of petrophysical properties. These results demonstrate that capillary transport is intrinsically anisotropic in calcarenite, with bedding orientation controlling both the amount of precipitated salt and the location of crystallizations. This study thus establishes a solid mechanistic framework for predicting salt weathering patterns in stratified heritage stones, and offers concrete perspectives for optimizing conservation strategies in coastal environments.

Investigation of Mechanical Properties of High-Performance Steel and Polypropylene Fiber Reinforced Concrete

Aditya Milmile — 2025-10-24

Fiber reinforcement significantly enhances the strength, toughness, and durability of concrete by reducing the propagation of microcracks in the concrete matrix. With the rising demand for high-performance concrete (HPC), this study investigates the mechanical properties of HPC with varying proportions of polypropylene (PP) and steel (ST) fibers. Supplementary cementitious materials (SCMs) toward partial replacement of ordinary Portland cement (OPC) were incorporated to prepare HPC mixes as a ternary composite system using Fly Ash (FA), Silica Fume (SF), and Ground Granulated Blast Furnace Slag (GGBS). Each HPC mix comprised two SCMs, accounting for 20% of the mass fraction of the OPC binder. The study encompassed fiber percentages ranging from 0 to 0.075% PP and 0 to 2% ST, incorporating them into the HPC mixes with gradual increases of 0.025% for PP and 0.5% for ST fiber by mass fraction. All HPC mixes were tested for mechanical properties using compressive and split tensile strength tests. The influence of SCMs on HPC was studied using X-ray diffraction (XRD) for microstructural analyses. It was found that the compressive and split tensile strengths of HPC increased up to an optimal fiber percentage and then decreased. A comparison of the test results of high-performance fiber-reinforced concrete with those of plain HPC revealed significant improvements in compressive and splitting tensile strengths by 26.59% and 57.74%, respectively. Also, the XRD analysis revealed that the composition of the SCMs in HPC was a significant and effective solution for the mechanical properties of the concrete.

Journal of Building Material Science

Salt Weathering in Anisotropic Calcarenite: Bedding-plane Controls on Sodium Chloride Precipitation Patterns

Investigation of Mechanical Properties of High-Performance Steel and Polypropylene Fiber Reinforced Concrete