This study proposes a method to convert non-structural calcium-rich construction and demolition waste fines into adsorbents of heavy metal ions by mixing waste fines with diammonium hydrogen phosphate solution to produce hydroxyapatite, which has high surface areas and excellent ion-exchange capacity with heavy metal ions. As a result, environmental polluting waste is converted into environmentally cleaning material. Waste putty powders was chosen as the representative waste to investigate the detailed formation process of hydroxyapatite and the key reaction parameters of the reaction. Results showed that hydroxyapatite can be produced on waste putty particles. Higher ageing temperatures or longer ageing duration are beneficial to the yield and crystallinity of the produced hydroxyapatite. Adsorption testing confirmed that Ni 2+ can replace Ca 2+ in the hydroxyapatite lattice, leading to the formation of a new crystal, arupite (Ni 3 (PO 4 ) 2 •8H 2 O), and contributing to a modest adsorption capacity for Ni 2+ (15 mg/g) for the hydroxyapatite-containing waste putty. Citation/Citar como: Chen, P.; Chen, X.; Wang, Y.; Wang, P. (2020) Preliminary Study on the Upcycle of Non-structural Construction and Demolition Waste for Waste Cleaning. Mater. Construcc. 70 [338], e220 https://doi.org/10.3989/ mc.2020.13819 RESUMEN:Estudio preliminar sobre el empleo de residuos de construcción y demolición no estructurales para la eliminación de residuos. Este estudio propone un método para convertir residuos de construcción y demolición no estructurales, ricos en calcio y pulverulentos, en adsorbentes de iones de metales pesados mezclándolos con una solución de hidrógenofosfato de diamonio para generar hidroxiapatita, la cual presenta una elevada área superficial y una excelente capacidad de intercambio iónico de iones de metales pesados. De este modo, un residuo contaminante se convierte en un material que limpia el medio ambiente. Se seleccionó residuo en forma de masilla en polvo como residuo representativo para investigar en detalle los procesos de formación de hidroxiapatita y los parámetros clave implicados en la reacción. Los resultados mostraron que la hidroxiapatita se puede producir en las partículas de los residuos empleados. La producción y la cristalinidad de la hidroxiapatita se ve favorecida por temperaturas de envejecimiento elevadas y prolongadas. Los ensayos de adsorción confirmaron que el Ni 2+ puede sustituir al Ca 2+ en la estructura de la hidroxiapatita, formándose un nuevo mineral, arupita (Ni 3 (PO 4 ) 2 •8H 2 O), y contribuyendo a una adsorción modesta de Ni 2+ (15 mg/g) por parte de la masilla de residuos con hidroxiapatita.

This paper introduces a novel emulsion explosive, which has three primary advantages, namely, the ability to easily adjust various detonation properties to desired values, decrease the overall cost of civil explosive products, and minimize environmental pollution during use. Immediate and time‐related experiments are performed in order to identify changing detonation properties of these new formulas. Our results show that both common clay and hollow glass micro‐spheres (HGMs) function as thermal diluents, which indicates that for a larger quantity of these additives, the weaker are the detonation properties under the condition of our experimental ratios (HGMs: from 5 wt.% to 15 wt.%; common clay: from 0 wt.% to 20 wt.%). Furthermore, a comparison of four alternative emulsion explosive compositions reveals that the longest storage time in this study is 5 weeks with No. 3‐3, which contains 15 wt.% HGMs and 10 wt.% common clay. In addition, nonlinear attenuation is observed and explained for that period.

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This paper investigates the influence of silica coated rubber on the performance of rubber mortars. A classical Stöber sol-gel method is applied to produce a layer of silica coating on rubber particles, which is used to partially replace the fine aggregates in concrete. The effects of the surface-modified rubber particles on the flowability, mechanical strength, capillary water absorption rate, and microstructure of mortars are examined. The results show that the silica coating on the rubber particles reduces the contact angle between the rubber particles from 120° to 103° (i.e., by 17°) and changes the hydrophobic properties from strong hydrophobicity to weak hydrophobicity. The mechanical strengths of mortars are significantly improved by the incorporation of surface-modified rubber particles, i.e., from 41.60% to 44.86% (compressive strength) and from 7.80% to 26.28% (flexural strength). In addition, the incorporation of surface modified rubber particles increases the density of the mortar’s microstructure and enhances the interfaces with its surrounding pastes.

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