Galal Fares

Nanosilica and its Future Prospects in Concrete

The implementation of nanotechnology in concrete has led to an active incorporation of nano silica in concrete in a global level. Different methods of nano silica production are available and vary from expensive to cost-effective routes. Nano silica particle sizes and their chemical and physical nature depend on the method of production. Several types of dispersed nano silica are recommended to be used in concrete due to practical reason. However, the dry powders of nano silica particles are difficult to be dispersed in concrete and require special types or family of nano superplasticizers. The effective addition of nS leads to C-S-H with improved cementitious properties.

Optimized Fresh and Hardened Properties of Strain Hardening Cementitious Composites: Effect of Mineral Admixtures, Cementitious Composition, Size, and Type of Aggregates

AbstractThe present paper thoroughly investigates the effects of mix design with various water-to-binder (W/B) ratios, types of mineral admixture and types and sizes of local sands on the tensile d...

Optimized Fresh and Hardened Properties of Strain-Hardening Cementitious Composites: Effect of Sand Size and Workability

AbstractThe feasibility of the preparation of strain-hardening cementitious composites (SHCC) relies to a great extent on the properties of one of its main constituents, quartz sand. The particle size distribution (PSD) of such sand should satisfy certain criteria specifically for SHCC to deliver quasi-static responses under tensile stress. The successful use of naturally available sand helps preparation of a cost-effective SHCC. The aim of the current paper was to evaluate the potential use of white quartz sand that is naturally available in the Arabian Gulf with different PSDs to produce different mixtures of SHCC. These mixtures were prepared with different ranges of workability to obtain optimized fresh and hardened properties with improved strain-hardening response. The effect of workability on the compressive, flexural and tensile properties has shown that there is an optimal workability range among the defined ranges that provided improved strain-hardening responses under tensile stress. The mode o...

Evaluation of Powdered Scoria Rocks from Various Volcanic Lava Fields as Cementitious Material

AbstractIn this study, the large deposits of volcanic scoria rocks (SRs) of the Arabian Peninsula were investigated as cement replacement materials. The powdered SRs procured from three separate regions (SR1, SR2, and SR3) were incorporated in concrete mixtures at three replacement levels (10%, 20% ,and 30%, by cement weight). Additionally, two reference concrete mixtures with silica fume (SF) and ground quartz sand (GS) were fabricated for benchmarking. Fresh properties, compressive strength, chloride-ion penetration resistance, and pore-size distribution from mercury intrusion porosimetry (MIP) were obtained. Microstructural and elemental spot analyses using field emission scanning electron microscopy (FESEM) analyses of samples from concrete mixtures were performed. The results showed that powdered SR samples exhibit clear variations in morphology and mineralogical compositions depending on the volcanic lava field. The strength activity index (SAI) of SR3 was higher than SR1 and SR2 indicating higher p...

HPC Composites Formulated to Counteract Early ASR Expansion

AbstractThe authors investigated the ability of different high-performance concrete (HPC) composites to restrain an alkali-silica reaction (ASR) in the presence of reactive aggregates. They evaluated the effectiveness of different binary and ternary blended cementitious systems comprising optimized contents of pulverized fly ash (PFA) and silica fume (SF) in suppressing ASR expansion. They assessed different mortar mixtures made of different contents of PFA (up to 40%) and SF (up to 15%) with water-to-binder (W/B) ratios of 0.27 for ASR expansion according to standard procedures for accelerated mortar bar test. The results showed a given pessimal combination among the ternary mixtures in which there was an obvious synergistic interaction where ASR expansion was at its minimum level.