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In this paper an overview is presented on the use of diatomaceous earth (DE) as a partial substitute for binder and fine aggregate in mortars. For this purpose, this paper was divided into two sections. In the first one, concepts related to physical, chemical and microstructural properties of DE, as well as results of previous studies about its reactivity used in different construction materials (cement, concrete, mortar, bricks, phase change materials etc.) were summarized and discussed. In the next section, the effects of using DE on the fresh, hardening and durability properties of cement and lime-based mortars were discussed. In general, the results suggest that increasing DE content may reduce mortar performance due to the high porosity of its particles. However, this deficiency was observed for DE contents higher than 20%, which, however, can be compensated for by using superplasticizer additives or by volumetric dosage instead of by weight one. This critical value of up to 20% of DE was calculated using T2 statistical on the scores of principal components analysis obtained from the results collected from publish manuscripts. Nevertheless, the results of this review research may contribute to provide information on an under-explored alternative source of supplementary cementitious materials (SCMs) and therefore help mitigate the negative effects generated by the cement industry and assist in the production of mortars with a lower carbon footprint that can play an important role in the thermal behavior of buildings. • State of the art systematic review of diatomaceous earth (DE) for mortar production. • Statistical analysis of the mechanical properties of mortar with DE. • Understanding the effects of DE on properties of mortars. • When up to 20% DE is used, the mechanical behavior of mortars can be improved. • Paths for the development of new studies on mortars incorporating DE are shown. [ABSTRACT FROM AUTHOR]

• Demolished concrete waste can be potentially utilised as recycled aggregates (RA). • Multi-stage processing and mechano-chemical treatment enhances the quality of concrete RA. • RAC incorporating treated RA shows better mechanical and durability properties. • Additional C S H formation is observed for RAC incorporating 35% treated RA. On account of the shortage of naturally occurring coarse aggregate, recycled aggregate (RA) made from crushed concrete debris is now used in the construction industry. With this rise in the utilisation of recycled aggregate in the construction sector, there has been extensive research into ways to improve its quality. The significant fraction of mortar remains that are left on the RA surface is the primary factor that affects its quality. Concrete made from RA loses strength and mechanical performance due to the attached mortar's increased porosity and water absorption values and the frailer transition region between the new mortar and aggregates. In order to minimise the old cement fractions and increase the quality, this paper studies the effect of concrete incorporating multi-stage processed RA from demolished concrete waste, followed by treatment with mechanical abrasion and sodium silicate immersion. The recycled aggregates were produced through multi-stage jaw crushing, followed by utilising natural aggregate, recycled aggregate, and recycled aggregate obtained after mechanical abrasion, followed by sodium silicate treatment for concrete mix design at various substitution percentages as coarse aggregates. The experimental investigation further progresses with the evaluation of mechanical and durability properties of concrete mixes, which is additionally followed by microstructural studies such as scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDAX), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Thermogravimetry-differential thermal analysis (TG-DTA). The outcomes demonstrate that two-stage treatment, such as mechanical abrasion followed by sodium silicate immersion, yields superior-quality RA. Recycled aggregate concrete (RAC) made with these treated aggregates illustrated an increase in workability and density with respect to an untreated RAC mix. Furthermore, comparable strengths in compression, flexure, and tension are found in treated RAC mixes, particularly at 35% replacement levels, with respect to concrete mixes comprised of natural aggregates. A similar trend is detected in the chloride penetration tests and water sorptivity tests. In addition, the microstructural investigation confirmed the formation of additional calcium silicate hydrate for treated RAC mixes, particularly for the 35% substituted RA mix. On the basis of the results, it is suggested that multi-stage jaw crushing followed by treatment through mechanical abrasion and sodium silicate can potentially enhance the mechanical, microstructural, and durability performance of RAC. [ABSTRACT FROM AUTHOR]

• Different percentages of red mud were added in UHPC. • 20% replacement of red mud was preferable with respect to pumpability and buildability. • Upcycling the red mud in UHPC is an energy-saving and low-cost strategy to address disposal of solid waste. This paper introduces a new application of industrial solid waste red mud to use as a cementitious material in the development of ultra-high performance concrete (UHPC) performances. In addition, utilization of red mud can reduce the environmental impact of red mud landfill. For gaining this aims, UHPC specimens were prepared with different contents of red mud and analyzed the effects of different RM contents on the fluidity, setting time, mechanical properties, durability, drying shrinkage and microstructure of the red mud-based UHPC. The results indicated that fluidity was reduced to 310 mm at 20% red mud level, but it still belongs to enormous fluidity, which is convenient for construction. In addition, it is worth noting that using red mud instead of cement can significantly shorten the setting time, providing a new method for applying the UHPC rapid-repairing process. Red mud-based UHPC mortar prepared with appropriate red mud instead of cement exhibits higher mechanical properties, better durability and reduced drying shrinkage of UHPC during curing. After curing for 28d, the highest compressive strength of UHPC samples containing 20% red mud was 129.5 MPa, the compressive strength of the UHPC samples' sulfate resistance was 136.6 MPa, and the drying shrinkage value was around 414 µm. Moreover, observed information from scanning electron microscopy (SEM) noted that red mud can fill the micro-cracks between particles of cementitious materials, make the structure more compact and form new hydrates. Finally, the two characteristics of low cost and energy consumption further promote the sustainable application of red mud-based UHPC. Therefore, replacing OPC with 20% RM is meaningful to produce a sustainable UHPC mixture and field applications. [ABSTRACT FROM AUTHOR]

• Utilizing lime mud as a filler can lead to the production of high-strength materials. • Lime mud can enhance material hydration by creating more nucleation sites. • The use of lime mud can refine pores and decrease pore structure. • Lime mud can be used in large replacement ratios, which can improve the sustainability of the mixture. Lime mud (LM) is a solid industrial byproduct with high alkalinity and calcium carbonate (CaCO 3) content produced by the paper industry. LM has been used and investigated as a supplementary cementitious material (SCM). However, using LM with a high replacement ratio causes agglomeration, which reduces the material's strength and has a detrimental effect on other properties. In addition to agglomeration, LM is unreactive; thus, in this work, a high replacement ratio (70%) of sand with raw LM was investigated in a mortar mixture containing silica fume (SF), considering the fast SF hydration properties of cement in a high alkaline environment, and river sand is used to reduce the agglomeration of LM. The effects of the replacement were then evaluated using compressive strength, X-ray diffraction, thermogravimetric analysis, mercury intrusion porosimetry (MIP), and scanning electron microscopy (SEM). The hydration kinetics were investigated using isothermal calorimetry. The experimental results showed that combining SF with a high replacement ratio (70%) of LM improves compressive strength and flexural strength by 16% and 59.7%, respectively. This is due to the filler nature of LM, which refines the pore structure. Furthermore, the highly alkaline environment provided by LM increased the secondary hydration of SF with cement, which also improved the strength. [ABSTRACT FROM AUTHOR]

• Pozzo-Lime is a low-carbon alternative material for cement for sustainable concrete. • Conducts less heat. • Lime is combined with pozzolanic materials. • Suitable for mortar and plastering. • With less cement used for structural concrete. Lime and lime-pozzolan-based binders are used in construction and restoration purposes for many centuries. Later its usage was reduced due to the major consumption of Ordinary Portland Cement (OPC). The usage of enormous cement in making concrete and mortar for constructing buildings and heavy structures leads to the indirect emission of greenhouse gas such as CO 2 and environmental impact to earth. At this situation, use of low-carbon alternative materials for cement is suggested for sustainable practice in concrete technology. Hence, Lime is the only natural binder which plays a major role in achieving sustainability in construction. Different mineral and organic admixtures can be added with lime to increase its cementitious properties. By using these lime-pozzolan binders in construction eco-friendly, affordable and durable structures can be constructed and cement usage is minimized to a great extent. The use of lime-based binders in concrete and mortar for building and restoration applications is discussed in this paper in general terms. The fresh, mechanical, microstructural, and durability properties are the ones that are reported in this study. [ABSTRACT FROM AUTHOR]

• CWP was used as a binder replacement in cement and lime mortars. • Results were compared in terms of mechanical, durability and microscale properties. • For cement mortars, the optimal substitution rate was 10–20%. • In cement mortars, the mechanical properties were unaffected up to 50% replacement. • In lime mortars, the mechanical properties increased up to 70% replacement. Ordinary Portland cement (OPC) is responsible for 8% of worldwide carbon emissions and the construction industry is in need of alternatives to minimise its impact. Waste products from foundries and furnaces are prime candidates as they can be high in reactive properties. This paper reports on the results of an experimental investigation into the effect of ceramic waste powder (CWP) as a binder substitute in cement and lime-based masonry mortars. As part of a comprehensive experimental investigation, standard cement and lime specimens were made with replacement rates of 0–60% and 0–80%, respectively, and moist cured for up to 90 days. The examined properties include compressive strength, tensile strength, dry bulk density and permeable voids, drying shrinkage, and pH. Based on the obtained results, the compressive and tensile strengths of cement mortars containing CWP not only experienced no significant adverse effect up to 50% replacement, but also increased at the substitution percentages of 10–20%. For the hydrated lime mortars, the compressive and tensile strengths were continuously enhanced up to 70% replacement of lime with CWP. These results were supported by the outcomes of the scanning electron microscopy (SEM) images and X-ray diffraction (XRD) analyses. These findings can introduce a useful application of CWP as a sustainable binder replacement in construction leading to reducing the carbon footprint of construction materials and the adverse environmental impact of CWP disposal in landfills. [ABSTRACT FROM AUTHOR]

• Energy efficiency in MW heating is improved by increasing the loss factor ε″. • The incorporation of EAF slag in asphalt mortars increased its loss factor ε″. • Within the 0.1–6 GHz range, the frequency 5.8 GHz yielded the highest value of ε″. • Microwave radiation at a frequency of 5.8 GHz can penetrate the pavement 7 cm. Microwave (MW) heating could contribute to the sustainability of the construction and maintenance of asphalt pavements. The relationship between frequency and the dielectric properties (i.e. loss factor and penetration depth) is crucial for maximising the MW heating efficiency. The paper aims to study the dielectric properties of conventional and electric arc furnace (EAF) slag asphalt mortars. Results showed that the addition of EAF slag enhanced the dielectric response of asphalt mortars. Moreover, a frequency of 5.8 GHz seems to be the best choice for deicing application and assisted-healing of surface layers up to 7 cm. [ABSTRACT FROM AUTHOR]