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• Green cementitious materials were prepared by synergistically utilizing demolition waste and industrial waste. • The variation pattern between the macro-properties of geopolymer and initial constituent molar ratios was comprehensively summarized. • The strong linear correlations were observed between initial component molar ratios and both flowability and compressive strength. Recycling waste materials for geopolymer synthesis offers a sustainable solution for reducing environmental impact from construction. In this study, the recycled concrete fine powder (RCFP) and granulated blast furnace slag (GBFS) were used to synthesize geopolymers, and the effects on physical performance, compressive strength, and microstructure were investigated. Building upon the existing results, the quantitative relationships between initial constituent molar ratios (Si/Al, Na/Al, and Si/Ca) and macro-properties of the geopolymers were explored and the influence mechanisms were analyzed. The findings demonstrate that the incorporation of GBFS significantly reduced setting time and increased compressive strength. Additionally, the blending of GBFS effectively enhanced the geopolymerization degree and generated more mixed gelling products of C-(A)-S-H, N-A-S-H and (C, N)-A-S-H, resulting in a refined internal structure of the matrix. The results revealed that the relationships between initial constituent molar ratios and macro-properties were not straightforward and involved multiple models. The initial and final setting times showed complex non-linear correlations with initial component molar ratios, while strong linear correlations were observed between initial component molar ratios and both flowability and compressive strength. A non-linear relationship was found between the setting time and fluidity. The outcomes contribute to the understanding of the interplay between composition, property, and structure in geopolymer materials and provide guidance for the composition design of geopolymers. [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]