Recycled aggregate concrete (RAC) was produced with industrially pre-carbonated recycled concrete aggregates (RCA). The clinker content was reduced by substituting Portland limestone cement and Portland cement with limestone and phonolite powder. Concrete RCA was compared to a reference concrete (NAC) produced with natural concrete aggregates and without clinker reduction. The reduction of water-to-powder ratio in the clinker-reduced concrete RAC allows to surpass the compressive strength of concrete NAC and to partly compensate for the increase of carbonation and chloride migration coefficients. However, the ratio of E-modulus to compressive strength is decreased in concrete RAC. While shrinkage is only marginally affected by the use of RCA and clinker reduction, the creep coefficient is decreased. The resulting concrete properties show that the cement clinker is utilized in a more efficient way when ground limestone and natural pozzolan (phonolite) powders are combined with Portland cement instead of Portland limestone cement. In particular, compressive strength, carbonation resistance and chloride resistance are all improved.

This study aimed to enhance calcined clay reactivity via mechanical or chemical treatments. Properties were analyzed using XRF, TGA, and XRD; reactivity was assessed with modified Chappelle and R³-bound water tests. XRD patterns for thermally (Th) and thermo-mechanically (ThM) treated clays were similar. Zeolite formation in thermo-chemically (ThC) treated clay was observed and confirmed by TGA with significant mass loss below 400°C. The reactivity of calcined clay exceeded that of untreated clay, in the order Th > ThM > ThC, as confirmed by tests. Subsequently, LC³ mortar was formulated using these activated clays. Assessments included heat of hydration and compressive strength over 90 days, along with XRD and TGA characterizations. The findings demonstrated that the trends in heat of hydration and compressive strength paralleled those observed in reactivity, with LC³-Th > LC³-ThM > LC³-ThC. Although the cement mortar had higher compressive strength than LC³ at 7 days, LC³ showed greater strength after 28 days. A correlation matrix and heat map were also created to analyze the relationship between reactivity and strength. Normalized values confirmed the findings, showing a strong correlation between the R³-bound water value, heat of hydration, and strength up to 90 days.

In the cement and concrete industries, technologies are being developed to reduce CO₂ emissions by fixing it as inorganic carbonates within cementitious materials. This study quantitatively analyzed the CO₂ content in cement pastes under different carbonation conditions using back-titration, thermogravimetry (TGA), and combustion-infrared absorption methods. The analysis of silica gel produced from the decomposition of C-S-H and gas components generated during the thermal analysis of carbonated samples allowed for an evaluation of the sample properties and an examination of the errors associated with each quantification method. Back-titration effectively decomposed carbonates and cement hydrates, accurately quantifying CO₂ regardless of the composition and amount of silica gel. In contrast, TGA tended to underestimate CO₂ as it failed to detect CO₂ derived from calcium carbonate polymorphs at lower temperatures. The combustion-infrared absorption method showed slightly higher CO₂ quantification compared to back-titration due to the influence of residual organic matter, and equipment without a desulfurization tube tended to quantify even more CO₂.

This study aims to provide a review of how electromagnetic waves, primarily frequency bands in telecommunications networks, interact with cement-based materials and presents recent approaches, including the integration of functional fillers or structural components into the materials, to modify these interactions. Based on a dataset comprising experimental results from various previous studies, the study provides a comprehensive evaluation of the effectiveness of approaches on not only shielding capability but also the reflection and transmissivity of electromagnetic waves when interacting with cement-based materials, and the mechanisms behind these effects. The use of metal- and carbon-based fillers with high conductivity is a fundamental approach to increase the wave shielding of the material through dielectric losses. Conversely, approaches using materials with low electrical conductivity, such as quartz, rice husk ash, expanded polystyrene, or glass, can increase the transmissivity of waves. However, the effectiveness varies and depends on the type, shape, and the fraction of fillers, as well as the frequency of waves. Furthermore, structural modifications, such as increasing thickness, applying coating layers, using a multi-layered structure, or embedding a metal sheet into the material, are also effective ways to enhance absorption, leading to a reduction in the transmissivity of waves.