Physical and mechanical characterization of Portland cement mortars made with expanded polystyrene particles addition (EPS)

El objetivo de este estudio es evaluar la influencia de la adición de distintos tipos y dosificaciones de poliestireno expandido, tanto comerciales como procedentes de reciclado, sobre las características físicas y mecánicas de morteros de cemento Portland. Las variables estudiadas fueron: consistencia, aire ocluido, densidad aparente, resistencias mecánicas, porosidad, absorción de agua y absorción acústica. Los morteros también se han caracterizado por microscopia electrónica de barrido. Con objeto de mejorar la trabajabilidad de los morteros se ha empleado aditivos aireante, retenedor de agua y fluidificante. Los resultados muestran que al aumentar la cantidad de poliestireno expandido la trabajabilidad y las resistencias mecánicas disminuyen. El empleo de aditivos mejora la trabajabilidad y la porosidad, permitiendo fabricar morteros con altos contenidos de residuo, con propiedades mecánicas adecuadas para su empleo como morteros de albañilería, revoco y enlucido.On this work the influence of the addition of different types (commercial and recycled) and contents of expanded polystyrene on the physical and mechanical properties of Portland cement mortars has been studied. Variables studied are: workability, air content, bulk density, mechanical strength, porosity, water absorption and sound absorption. Mixtures have been also characterized by scanning electron microscopy. Air-entraining agents, water retainer and superplasticizer additives have been used in order to improve the workability of mortars. The results show that the workability and mechanical strength decreases with increasing content of expanded polystyrene. Additives improve the workability and porosity, allowing manufacture mortars with high levels of recycled material that show mechanical properties suitable for use as masonry mortars, stucco and plaster.Las autoras desean agradecer al Ministerio Español de Ciencia e Innovación la financiación del proyecto BIA2007-61170, en el marco del cual se ha realizado el presente trabajo, y la concesión de la beca FPI (BES-2009-012166) a Verónica Ferrándiz Mas que le permite desarrollar su Tesis Doctoral, de la que el presente trabajo forma parte

Lightweight mortars containing expanded polystyrene and paper sludge ash

The objective of this research was to develop lightweight cement mortars with good thermal-insulation properties by incorporating expanded polystyrene (EPS) and paper sludge ash (PSA), both of which are problematic waste materials. The mortars formed had low thermal conductivity and low bulk density compared to control samples. Ground EPS produced lower thermal conductivity samples than powdered EPS. Resource efficient mortars containing up to 20% PSA, and 60% of EPS are considered suitable for use in rendering and plastering applications

Optimising the bioreceptivity of porous glass tiles based on colonization by the alga Chlorella vulgaris

Green façades on buildings can mitigate greenhouse gas emissions. An option to obtain green facades is through the natural colonisation of construction materials. This can be achieved by engineering bioreceptive materials. Bioreceptivity is the susceptibility of a material to be colonised by living organisms. The aim of this research was to develop tiles made by sintering granular waste glass that were optimised for bioreceptivity of organisms capable of photosynthesis. Tiles were produced by pressing recycled soda-lime glass with a controlled particle size distribution and sintering compacted samples at temperatures between 680 and 740 °C. The primary bioreceptivity of the tiles was evaluated by quantifying colonisation by the algae Chlorella vulgaris (C. vulgaris), which was selected as a model photosynthetic micro-organism. Concentrations of C. vulgaris were measured using chlorophyll-a extraction. Relationships between bioreceptivity and the properties of the porous glass tile, including porosity, sorptivity, translucency and pH are reported. Capillary porosity and water sorptivity were the key factors influencing the bioreceptivity of porous glass. Maximum C. vulgaris growth and colonisation was obtained for tiles sintered at 700 °C, with chlorophyll-a concentrations reaching up to 11.1 ± 0.4 μg/cm2 of tile. Bioreceptivity was positively correlated with sorptivity and porosity and negatively correlated with light transmittance. The research demonstrates that the microstructure of porous glass, determined by the processing conditions, significantly influences bioreceptivity. Porous glass tiles with high bioreceptivity that are colonised by photosynthetic algae have the potential to form carbon-negative façades for buildings and green infrastructure

The mechanism of hydration of MgO-hydromagnesite blends

The hydration of reactive periclase (MgO) in the presence of hydromagnesite (Mg 5 (CO 3 ) 4 (OH) 2 ·4H 2 O) was investigated by a variety of physical and chemical techniques. Hydration of pure MgO-water mixtures gave very weak pastes of brucite (Mg(OH) 2 ), but hydration of MgO-hydromagnesite blends gave pastes which set quickly and gave compressive strengths of potential interest for construction applications. The strengths of the blends increased with hydration time at least up to 28days, and were not significantly decreased by increasing the hydromagnesite content up to 30%. Raman spectroscopy suggests that an amorphous phase, of composition between that of brucite, hydromagnesite and water, may form. Small amounts of calcite also form due to CaO in the MgO source. Thermodynamic calculations imply that the crystalline phase artinite (MgCO 3 ·Mg(OH) 2 ·3H 2 O) should be the stable product in this system, but it is not observed by either XRD or FTIR techniques, which suggests that its growth may be kinetically hindered

Waste-Based porous materials as water reservoirs for the internal curing of Concrete. A review

This review collates findings from more than 100 scientific publications regarding the performance of several waste-based porous materials (WASPORs) as water reservoirs for the internal curing of concrete. Results obtained by using recycled concrete aggregates, crushed ceramics, coal bottom ash, artificial waste-based aggregates, different powder materials and porous fibres were included. The influence of these WASPORs on the consistence, hydration, setting, microstructure, density, strength, modulus of elasticity, autogenous deformation, drying shrinkage and durability properties of concrete were analysed. General recommendations for suitable characterization of WASPOR and mix design are also given. The differences in water absorption capacity between the different porous materials studied have been used for explaining several of the observed phenomena. A moderate water absorption capacity together with a quick water desorption capacity were found to be among the key factors that define the internal curing efficiency of the proposed WASPORs. © 2021 The Author(s