Gels of calcium-silicate-hydrates (C-S-H) are the glue that is largely responsible for the mechanical properties of cement. Despite their practical relevance, their nano-scale structure and mechanics are still mainly unexplored, because of the difficulties in characterizing them in a complex material like cement. We propose a colloidal model to investigate the gel mechanics emerging in the crit...

Both clays and calcium silicate hydrates(the main hydration products of Portland cements) exhibit a microstructure made up of lamellar particles. The microscopic mechanism responsible for the macroscopic creep of such materials is often described as the relative sliding of the sheets. This paper proposes a micromechanical approach to estimate the macroscopic creep behavior rising from this micr...

The relationship between composition, structure, and resistance to fracture remains poorly understood. Here, based on molecular dynamics simulations, we report that 1 sodium silicate glasses (NS) and calcium–silicate–hydrates (CSH) feature an anomalous maximum in fracture toughness. In the framework of topological constraint theory, this anomaly is correlated to a flexible-to-rigid transition, ...

A poorly crystalline class of calcium silicate hydrates known as C–S–H possesses extensive disorder and structural variations at the nanometer scale. The extent of these variations has generally obscured a comprehensive understanding of the C–S–H nanostructure, but new relationships between solubility and structure appear to shed new light on this old problem. These relationships were inspired ...

The incorporation of pozzolanic materials in concrete has many beneficial effects to enhance the mechanical properties of concrete. The calcium silicate hydrates in cement matrix of concrete increase by pozzolanic reaction of silicates and calcium hydroxide. The fine pozzolanic particles fill spaces between clinker grains, thereby resulting in a denser cement matrix and interfacial transition z...

The binding of alkalis and calcium to silicate hydrate (C-S-H) can be measured by cation exchange using cobalt hexamine solution with adapted pH. effective capacity (CEC) decreased at higher Ca/Si in C-S-H. A maximum chargeexch/Si 0.08–0.10 was = 0.8 decreasing 0.01–0.02 1.6. At high Ca/Si, only a minor fraction Ca present exchangeable sites, while most the Ca2+ interlayer or surface specifical...

The origin of different stability crystalline calcium silicate hydrates was investigated. tobermorite crystal has been used as an analog cement hydrate that is being mostly manufactured material on earth. Normal thermally unstable and transforms to amorphous at low pressure. Meanwhile, anomalous with high Al content does not significantly transform under pressure or temperature. Conducted X-ray...

We investigate the basic creep and fracture response of fine recycled aggregate concrete using nanoscale mechanical characterization modules integrated with nonlinear micromechanical modeling machine learning methods. Fine mortar exhibits a larger volume fraction micropores low-density calcium silicate hydrates compared to natural sand mortar. In return, hard aggregates. The macroscopic logarit...