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To generate sustainable mortars, this study investigated the impacts of adding two wastes into portland cement mortar: polyurethane powder waste (PU), and foundry exhaust sand (FES). The tests were carried out utilizing a response surface methodology (RSM) configuration with four different manufacturing variables: sand to cement ratio, coarse sand content (CS), FES, and PU replacing natural sand (NS). Compressive strength, modulus of elasticity, void index, and water absorption (Wa) all had substantial fitting values in the data. Furthermore, the experimental findings show that the adopted model is capable of accurately predicting the outcomes, and an optimized mortar combination was discovered and is presented. [ABSTRACT FROM AUTHOR]

The reuse of waste in civil construction brings environmental and economic benefits. However, for these to be used in concrete, it is necessary a previous evaluation of their physical and chemical characteristics. Thus, this study aimed to characterize and analyze the waste foundry exhaust sand (WFES) for use in self-compacting concrete (SCC). Foundry exhaust sand originates from the manufacturing process of sand molds and during demolding of metal parts. It is a fine sand rich in silica in the form of quartz collected by baghouse filter. Characterization of WFES was conducted through laser granulometry, scanning electron microscopy (SEM) in the energy dispersive spectroscopy (EDS) mode, X-ray diffraction (XRD), X-ray fluorescence (XRF), Fourier transform infrared spectroscopy (FTIR), thermogravimetry (TG) and derivative thermogravimetry (DTG) techniques. The waste was classified as non-hazardous and non-inert, with physical and chemical properties suitable for use in SCC composition, as fine aggregate or mineral addition. Five mixtures of SCC were developed, in order to determine the waste influence in both fresh and hardened concrete. The properties in the fresh state were reached. There was an increase in compressive strength and sulfate resistance, a decrease in water absorption of self-compacting concrete by incorporating WFES as 30% replacement. [ABSTRACT FROM AUTHOR]

The addition of Superabsorbent Polymer (SAP) decreases the effect of autogenous shrinkage present in pastes, mortars, and concretes. In this study we investigated the influence of the addition of SAP in self-compacting cement paste mixtures. Eighteen 5 × 10 cylindrical specimens were molded in all, three for each mixture (CPII base, CPII 0.15%SAP/600μm, CPII 0.15%SAP/800 μm, CPV base, CPV 0.15%SAP/600 μm, CPV 0.15%SAP/800 μm). Two types of cement were tested, CP II-Z and CP V-ARI with 0.15% of weight replaced per two diameters of SAP (600 μm and 800 μm). The samples followed the standards required. Mini slump tests were carried out in the fresh state, and uniaxial compressive strength, elastic modulus, specific mass, absorption, and air content in the hardened state after 28 days. The results obtained show the SAP is high indicated to replaced cement in small % of weight i/to fresh and hardened paste. Likewise, the group mix n° 3 composed of CPII 0.15% of SAP with 800 μm diameter presented the best result. [ABSTRACT FROM AUTHOR]

[Display omitted] • The use of the waste foundry exhaust sand (WFES) and the concrete potential for corrosion. • Using WFES as a partial substitute (10%–40%) for natural sand in self-compacting concrete. • Methods such as Slump flow, T500, V Funnel and L Box were used as rheological parameters. • The compressive strength increased with the increase of the WFES content. • The mixtures showed negligible corrosion probability and very low permeability to chloride ions. Several studies have already been conducted using residues to substitute or be added to Self- Compacting Concrete (SCC), including Waste Foundry Sand (WFS), yet there are still failures when using Waste Foundry Exhaust Sand (WFES), with respect to the potential for concrete corrosion. This study assesses using WFES as a partial substitute (10%, 20%, 30% and 40%) for natural sand. The mixtures showed negligible corrosion levels and very low permeability to chloride ions due to high electrical resistivity. The potential for corrosion was low and uncertain. The results indicated that fine marble and granite powder and WFES particles act as good filler materials, hindering harmful agent penetration, consequently increasing the durability of the concrete compared with the control concrete. The properties were improved using 30% WFES. [ABSTRACT FROM AUTHOR]