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This study introduces innovative concepts for closed-loop recycling waste concrete to produce fully recycled concrete (FRC). Multiple test methods and characterization techniques were used to evaluate the physical properties and durability of four types of concrete (normal concrete, recycled aggregate concrete, recycled cement concrete and FRC). The fresh density, compressive strength, ultrasonic characteristics, chloride resistance, water adsorption properties, carbonation behaviors, and microstructure characteristics of these concretes were investigated. The water absorption behavior of FRC can be divided into three stages, with the initial stage having a water absorption rate three times that of ordinary concrete. It was found that carbonation depth varied among different concrete types, influenced by binder quality, which can affect the porosity and mechanical properties. Overall, recycled cement concrete and FRC demonstrate considerable potential for reducing carbon emissions, with total emissions of 59.152 kgCO 2 /m3, representing an 85 % reduction compared to ordinary concrete. [Display omitted] • Fully recycled concrete (FRC) with 100 % recycled cement + 100 % recycled aggregates were prepared. • Physical performance and carbon emissions of normal concrete, recycled aggregate concrete, recycled cement concrete and FRC were compared. • The water absorption behavior of FRC can be divided into three stages, with the initial stage three times faster than ordinary concrete. • Recycled cement concrete and FRC demonstrate an 85 % reduction of carbon emissions compared to ordinary concrete. [ABSTRACT FROM AUTHOR]

[Display omitted] • Marine sand was used to prepare foamed lightweight soil (MS-FLS). • Increased MS content decreased mechanical properties and durability of MS-FLS. • Increased shell content decreased the compressive strength and durability of MS-FLS. • Increased chloride ion content improved the sulfate resistance of MS-FLS. • MS-FLS mixtures are applicable in embankment engineering (>0.3 MPa) Mixing foamed lightweight soil (FLS) with marine sand (MS) can be a sustainable approach for maximizing waste resources, although the fundamental properties (the physical performance, durability, and microstructural behaviors) of MS-mixed FLS (MS–FLS) have not been investigated, and this significantly restricts its engineering application. Thus, in this study, macroscopic and microscopic experiments are conducted to comprehensively explore the properties of MS–FLS with different MS, chloride (Cl−), and shell contents. The results of the macroscopic tests reveal that MS–FLS exhibits a fluidity of 160–229 mm, a volumetric water-absorption rate of 13.1 %–19.5 %, and an unconfined compressive strength (UCS) of 0.95–2.64 MPa. Further, the flow of bubbles is promoted as the fluidity and water-absorption rate change, thus accumulating the bubbles with relatively large pore sizes and causing an increase in the overall relative pore size. Although the durability is reduced to varying degrees via wet cycling, freeze–thaw cycling, sulfate (SO2 − 4) erosion, and long-term outdoor exposure, most of the UCS values can still satisfy the requirement for subgrade engineering applications. Moreover, the microscopic tests indicate that the pore size increases with the increasing MS content, whereas the pore-wall thickness, cement density, mechanical properties, and durability decrease. As the shell content increases, the UCS and durability decrease considerably owing to the smooth, surface-induced weak points and low water-absorption capacity of the shells; however, the UCS can still satisfy engineering requirements. Finally, the increased Cl− content can improve the SO2 − 4 resistance due to the generated Friedel's salt, which fills the micropores in cement-hydration products, and this facilitates strengthening. Therefore, the UCS values of most MS–FLS specimens are > 0.3 MPa before and after the durability tests, revealing their promise for subgrade engineering applications. [ABSTRACT FROM AUTHOR]

• Evaluation of self-compacting concretes produced with MK, RHA, limestone filler and hydrated-lime. • Metakaolin and rice husk improve the viscosity of SCC due to their higher specific surfaces. • Even with low PC consumption it was possible to obtain SCC with compressive strength up to 46 MPa. • Incorporation of SCM reduced the Cl- ion diffusion and increased the resistivity of the SCC. Self-compacting concrete (SCC) is a high-performance concrete that has gained prominence in recent years due to its high fluidity and cohesion characteristics. In this material, the use of supplementary cementitious materials (SCM) is necessary for the consolidation properties and durability requirements to be achieved. SCM obtained from waste or industrial by-products can improve SCC properties and reduce the environmental impact associated to Portland Cement (PC) production. In light of these facts, the present paper addressed the effects of high levels of mineral additions (metakaolin, rice husk ash and limestone filler) and hydrated-lime on the physical (ultrasonic pulse and capillary absorption), mechanical (compressive strength) and durability (carbonation resistance, chloride ion diffusion and electrical resistivity) properties of SCC. The results showed that metakaolin and rice husk ash increase the viscosity of SCC due to their larger specific surface area. The simultaneous incorporation of high content of mineral additions reduced the compressive strength of SCC. However, it was possible to obtain concretes with compressive strength between 22 and 46 MPa at 28 days and with adequate physical performance and durability. The addition of hydrated-lime to SCC proved efficient, mainly due to reduced carbonation depth associated to alkaline reserve replacement. [ABSTRACT FROM AUTHOR]

• MgO boards displayed comparable physical characteristics as traditional board types. • Gypsum/wood boards were more vulnerable to soak-dry and freeze-thaw than MgO boards. • MgO boards had similar resistance to soak-dry and freeze-thaw as fibre cement boards. • Mg oxysulphate boards were more sensitive to high humidity than Mg oxychloride boards. The use of sheeting materials within the construction industry is becoming increasingly common as building materials and the way they are used evolves. Recently, magnesium-based construction boards have received more attention as alternatives for traditional sheeting materials. This is due to some of their enhanced properties, particularly fire resistance and lower embodied carbon. However, the lack of standardised documentation has caused concern regarding their composition, performance and long-term behaviour. This paper evaluates some of the test methods commonly used when assessing the performance of construction boards. A comparison between relatively novel magnesium-based boards and traditional boards is also conducted. Physical, mechanical and durability properties are investigated. Magnesium-based boards can provide relatively good bending strength values and water absorption behaviour which is comparable with other board types. Findings also demonstrate good performance for magnesium-based boards when exposed to soak-dry and freeze-thaw cycles. They suffered relatively small changes in bending strength, similar to that of fibre cement boards and superior to that of gypsum plasterboards and wood-based boards. [ABSTRACT FROM AUTHOR]