Masonry retaining walls constitute an essential component of historic and urban infrastructure in seismic regions; however, their seismic performance remains insufficiently quantified due to material heterogeneity, limited tensile capacity, and complex soil–structure interaction. This study investigates the seismic response of historic stone masonry retaining walls using a finite element-based anisotropic macro-modeling approach. The analysis focuses on the perimeter retaining walls of Emirgan Grove in Istanbul, which represent culturally significant heritage structures constructed from natural limestone and cement–lime mortar. Material properties were defined based on experimental test results and representative values reported in the literature, while composite anisotropic behavior was incorporated into the numerical models. Static loads, earth pressures, and seismic actions were applied in accordance with the Turkish Building Earthquake Code (TBEC-2018) using the equivalent static earthquake load method. Representative wall segments with heights of 2.5 m, 3.5 m, 4.0 m, and 6.30 m were analyzed. The numerical results show that maximum compressive stresses reached approximately 0.48 MPa, remaining well below the allowable limit of 4.50 MPa, while maximum tensile stresses of about 0.28 MPa did not exceed the allowable tensile limit of 1.00 MPa. In contrast, shear stresses locally reached approximately 0.25 MPa, exceeding the allowable shear limit of 0.10 MPa, particularly along the soil–wall interface in taller walls. Sliding stability was satisfied in all cases, whereas overturning and shear behavior governed seismic vulnerability. These findings confirm that wall height is the primary parameter controlling seismic response and demonstrate the effectiveness of the proposed framework for preservation-oriented seismic safety assessment of historic masonry retaining walls.

Sustainability and nearly zero-energy consumption of new and existing buildings is a keystone in the new guidelines established by the European Commission. Likewise, waste management is in the focus of reducing the impact of industrial processes. The use of industrial byproducts, such as biomass ashes (BA), can be an interesting solution for waste valorization, reducing the carbon footprint and enhancing sustainability. In addition, Phase Change Materials (PCMs) can be used for improving energy efficiency due to their thermal storage capacity. An experimental study on the effect of biomass ash (BA) and PCM on the microstructure, chemical, physical and mechanical properties of cement–lime pastes was carried out. The partial replacement of cement with BA reduced compressive strength although did not substantially modify other paste properties, while the addition of PCM had a huge impact on microstructure and, therefore, physical and mechanical properties. PCM had a remarkable effect on thermal properties, endowing thermal storage capacity and reducing thermal conductivity, and the combination with BA further improved paste thermal properties.

With the development of novel production routes enabling near-zero emissions from lime manufacturing, the use of lime as a carbon-sequestering component in cementitious materials has attracted increasing attention. To address the intrinsically low early-age strength of lime-enriched binders (LP), this study investigates the modification effect of polyvinyl alcohol (PVA) on LP, with systematic comparisons to ordinary Portland cement (PO) and pure lime systems (LE). The results indicate that, in terms of mechanical performance, the incorporation of PVA significantly enhances the early-age strength of LP, particularly the flexural strength, which increases by 119.3%. In contrast, the strength of PO shows a certain degree of reduction after PVA addition. Regarding carbon uptake performance, the CO2 sequestration capacity of PO and LE increases by 16.8% and 16.9%, respectively, whereas that of LP slightly decreases by 5.5%. From the hydration perspective, both the heat release rate and cumulative heat of PO and LP are reduced after PVA incorporation. Combined with microstructural analysis, the mechanical enhancement of LP induced by PVA is mainly attributed to the polymer film-forming effect, which compensates for the negative impact caused by the inhibition of hydration.

Abstract. Ocean alkalinity enhancement (OAE) is a proposed method for atmospheric carbon dioxide removal (CDR), and involves the addition of alkaline minerals to surface waters to elevate seawater alkalinity and enhance atmospheric CO2 storage. Cement kiln dust (CKD) and lime kiln dust (LKD) are alkaline side streams from the cement and lime industry that have OAE potential due to their widespread availability and fine particle size. Here, we evaluated the dissolution kinetics, CO2 sequestration potential, and ecological risks of CKD and LKD by means of laboratory dissolution experiments. A reactive fraction (∼ 25 % in LKD and ∼ 29 % in CKD) dissolved rapidly within 24 h, with most dissolution occurring within the first hour. Dissolution provided a concomitant alkalinity release that was higher for LKD (up to 8.0 ± 0.5 mmol alkalinity per g) than CKD (2.4 ± 0.2 mmol g−1), thus providing a sizeable CO2 sequestration capacity for LKD (297 ± 20 g CO2 per kg) and CKD (88 ± 6 g CO2 per kg). Based on current industrial production rates, this translates into global CDR potentials of up to 8.7 ± 0.6 Mt CO2 yr−1 for LKD and 25 ± 2 Mt CO2 yr−1 for CKD. These estimates suggest that both materials could be viable OAE feedstocks, although further testing under conditions that more closely mimic natural coastal conditions is needed. Furthermore, we hypothesize that the substantial residual calcite content of LKD (∼ 54 %) and CKD (∼ 37 %) may provide additional sequestration via metabolic dissolution in marine sediments. However, kiln dust deployment will generate elevated turbidity levels that may exceed environmental thresholds, underscoring the need for carefully designed application strategies to minimize local ecological impacts.

Abstract Interlayer bonding in 3D concrete printing is influenced by the hydration progress and surface moisture of the previously printed layer. For effective quality control, continuous in situ monitoring of interlayer surface properties is required. This study investigated reflection intensity as a method for in situ measurements during the hydration of CEM I mixtures with varying retarder contents. Additional factors influencing the reflection intensity are also examined. Two laser line scanners with different wavelengths were used to track hydration over 72 h. Vicat tests and isothermal calorimetry served as reference methods. Across all the mixtures, the reflection intensity exhibited a repeatable pattern with five different stages. A sharp increase in intensity during the third stage was consistent with the acceleration period of hydration. These findings suggest that reflection intensity measurements could serve as a promising tool for evaluating interlayer bonding in 3D concrete printing. Graphical abstract The material used in this study is a cement lime, based on CEM I 42.5 N, with varying retarder content. From each batch of material, two samples were prepared for Vicat testing, two samples were prepared for isothermal calorimetry measurements, and one sample was cast for monitoring the reflection intensity. Two laser profile scanners were used, operating at 405 nm and 658 nm, respectively. Data were acquired for 72 h. The results show a strong increase in reflection intensity during the acceleration period.

Introduction. This paper presents a laboratory study investigating the mechanical behavior of silty soil reinforced with hydraulic binders (cement and lime) using a direct shear apparatus. A series of direct shear tests was performed on silty soils treated with hydraulic binders. Methods. The tests were conducted at a relative density of 50 %, under three normal stresses, with cement and lime contents of 0, 1, 3, 5, and 7 %, and a water content of 10 %. Results. The shear strength of cement-treated silt increases with cement content up to 6 % and then stabilizes. For lime-treated silt, the shear strength decreases at a lime content of 1 % and then stabilizes; thus, the contractive behavior increases with higher lime content. The internal friction angle increases with cement content and then stabilizes, with a slight decrease observed at a cement content of 7 %. Cohesion increases linearly with cement content. Lime addition enhances soil contractiveness; cohesion increases slightly up to a lime content of 3 % and then decreases. For the silt treated with the cement–lime mixture, the test results show that shear strength increases with normal stress compared to the untreated soil.

Soil permeability is an important factor in the mining and geotechnical industry, impacting slope stability and tailings management. It directly influences the stability of structures, the control of water in tailings ponds, and the safety of workers. Various additives, such as cement kiln dust (CKD), bentonite, fly ash, polymers, lime, and asphalt, are incorporated into soil structures to improve permeability and stability. Any significant changes in soil permeability will alter the soil’s behavior. However, the long-term effect of most additives on structures remains unexplored. This study investigates the long-term impact of CKD on the permeability of a CKD-treated slope. The slope surface was treated with 0%, 5%, 10%, and 15% of CKD by the dry weight of the soil in 2008 and was evaluated in 2024. The permeability test results of the collected soil sample from the slope (2024) showed that the permeability of the soil decreases with an increase in the soil CKD content. The coefficient of permeability, k, is more than 100 times less for a CKD content of 15% by the dry weight of the soil compared to the permeability of the untreated native soil. The treated soil becomes almost impermeable when the CKD content increases to 20% (by the dry weight of the soil). However, the treated slope’s permeability increased over time, possibly due to erosion, resulting in a reduction in CKD content. The surface permeability of the slope exhibits an irregular distribution, resulting from the evolving spatial distribution of Cement Kiln Dust over time.

The multiple linear regression analysis (MLR) is one of the most mathematical tools that widely used in recent decades by several investigations research for the prediction of the mechanical properties of energy-efficient building materials. For this purpose, the present study aims to predict and to estimate the compressive strength properties of the compressive stabilized earth blocks (CSEB) using the multiple linear regression analysis (MLR). The statistical modeling is carried out in this work based to the experimental results obtained using different independent variables of cement content, compaction pressures, lime and resin concentrations. The MLR model performed during this investigation is statistically significant with a good correlation between the experiment and the calculated data. The performance evaluation of the developed model was tested by the analysis of the statistical parameters of the coefficient of determination (R²), significance level (Sig.), standardized coefficient (β), t-test value and the variation inflation factor (VIF). Based on the obtained results, the MLR model gives high correlation for compressive strength prediction of CSEBs (R² of 0.82). Moreover, the findings conclude that the cement content has significantly impacts compressive strength values of CSEBs, followed by compaction pressures, lime and resin concentrations. Standardized coefficients of 0.74, 0.44, 0.22, and -0.03 are obtained respectively for each independent variable.

Synergistic Influence of Cement–Lime Stabilization on the Mechanical Properties and Mineralogical Changes of Sabkha Soils from Aïn M’lila

In Hungary, on-site mixed stabilization of cohesive soil is considered only as soil improvement not a proper pavement layer, therefore its bearing capacity is not taken into account when designing pavement. It was our hypothesis that on low-volume roads built on cohesive soil, lime or lime–cement stabilization can be an alternative to granular base layers. A case study was conducted to obtain initial results and to verify the research methodology. The efficacy of lime stabilization was evaluated across eight experimental road sections, with a view of assessing its structural and economic performance in comparison with crushed stone base layers reinforced with geo-synthetics. The results of the testing demonstrated elastic moduli of 120–180 MPa for the lime-stabilized layers, which closely matched the 200–280 MPa range observed for the crushed stone bases. The results demonstrated that lime stabilization offers a comparable load-bearing capacity while being the most cost-effective solution. Furthermore, this approach enhances sustainability by enabling the utilization of local soils, reducing reliance on imported materials, minimizing transport-related costs, and lowering carbon emissions. Lime stabilization provides a durable, environmentally friendly alternative for road construction, effectively addressing the challenges of material scarcity and rising construction costs while supporting infrastructure resilience. The findings highlight its potential to replace traditional base layers without compromising structural performance or economic viability.

This study presents a novel approach to determine the composition of masonry mortars and their types from cement, lime, and cement–lime using an artificial neural network (ANN). It also allows the preparation of mortar recipes for the conservation of historical masonry objects with properties similar to the original ones, but using currently available raw materials. An ANN was trained using a set of cement, lime, and cement–lime mortars with known compositions. The properties chosen for the ANN’s analysis included total porosity, specific density, insoluble residue content, silicone (SiO2) content, calcium (CaO) content, Si/Ca ratio in grout, and compressive strength. The use of ANNs allows for the determination of mortar composition with a validation error of less than 5% and a method of classification of the type of mortar that gives correct answers in more than 93% of cases, proving the usefulness of ANNs in determining the type and composition of masonry mortars relevant for the conservation of historical masonry structures.

Maintenance dredging produces large volumes of fine sediments that are commonly discarded, despite increasing pressure for beneficial reuse. Lime–cement stabilization offers one pathway, yet field performance is highly variable. This study juxtaposes two French marine dredged sediments—DS-F (low plasticity, organic matter (OM) ≈ 2 wt.%) and DS-M (high plasticity, OM ≈ 18 wt.%)—treated with practical hydraulic road binder (HRB) dosages. This is the first French study that directly contrasts two different DS types under identical HRB treatment and proposes practical boundary thresholds. Physical indexes (particle size, methylene-blue value, Atterberg limits, OM) were measured; mixtures were compacted (Modified Proctor) and tested for immediate bearing index (IBI). IBI, unconfined compressive strength, indirect tensile strength, and elastic modulus were determined. DS-F reached IBI ≈ 90–125%, UCS ≈ 4.7–5.9 MPa, and ITS ≈ 0.40–0.47 MPa with only 6–8 wt.% HRB, satisfying LCPC-SETRA class S2–S3 requirements for road subgrades. DS-M never exceeded IBI ≈ 8%, despite 3 wt.% lime + 6 wt.% cement. A decision matrix distilled from these cases and recent literature shows that successful stabilization requires MBV < 3 g/100 g, plastic index < 25%, OM < 7 wt.%, and fine particles < 35%. These thresholds permit rapid screening of dredged lots before costly treatment. Highlighting both positive and negative evidence clarifies the realistic performance envelope of soil–cement reuse and supports circular-economy management of DS.

In the context of intensified construction and stricter requirements for the energy efficiency of buildings, the use of thermal insulation materials and technologies is becoming particularly important. One promising area in this field is the use of thermal insulation mixtures, which are versatile, adaptable, and highly reliable in operation. Mixtures based on fillers with a porous structure and materials that impart thermal insulation properties, which provide higher thermal insulation properties, are of great interest. However, the development of dry thermal insulation mixtures is hampered by insufficient study of their physical, mechanical, and operational characteristics. This article presents the results of research work on the development and study of dry building thermal insulation mixtures. A distinctive feature of the work is the creation of a composition of dry building thermal insulation mixtures based on local raw materials, such as diatomite, its thermal modification at a temperature of 900 °C, the use of expanded perlite sand, lime, and Portland cement. Research into the properties of modified diatomite has shown that its surface after thermal treatment differs from the surface of unburned diatomite in that it becomes more active and has a 3–4 times higher increase in strength. Modified diatomite and expanded perlite sand have low thermal conductivity, and this property was used in the creation of building thermal insulation mixtures, which was confirmed by research, as the thermal conductivity coefficient ranged from 0.128 to 0.152 W/m °C. The developed dry thermal insulation lime–cement mixture is intended for both interior and exterior finishing works, which is confirmed by the results obtained for determining the frost resistance of the solution and the frost resistance of the contact zone, and corresponds to the F35 grade and has a strength of up to 3.59 MPa.

High-plasticity clay soils pose significant challenges in geotechnical engineering due to their poor mechanical properties, such as low strength and high compressibility. Lime–cement stabilization offers a sustainable solution, but optimizing additive proportions requires advanced analytical approaches to decipher complex soil-stabilizer interactions. This study investigates the stabilization of high-plasticity clay soil (CH) sourced from Kano, Nigeria, using lime (0–30%) and cement (0–8%) for thirty (30) sample combinations to optimize consolidation and strength properties. Geotechnical laboratory tests (consolidation and UCS) were evaluated per ASTM standards. Multivariate analysis integrated principal component analysis (PCA) with regression modeling (PCR) for sensitivity and causality assessment. Optimal stabilization (15% lime + 6% cement) significantly improved soil properties: void ratio reduced by 58% (0.60→0.25), porosity by 49.5% (0.38→0.19), UCS increased by 222.5% to 2670 kPa (28 days), preconsolidation stress by 206% (355.63→1088.92 kPa), and compressibility modulus by 16% (7048→10,474.28 kPa). PCR sensitivity analysis attributed 46% of UCS variance to PC1 (compressibility parameters: void ratio, porosity, compression index; β = 0.72). PCR Causality analysis shows improvment with curing (R2: 68.7% at 7 days→83.0% at 28 days; RMSE: 11.2→7.8 kPa). PCR establishes compressibility reduction as the dominant causal mechanism for strength gain, providing a robust framework for dosage optimization beyond empirical approaches.

Optimized composite lime cement plasters with phase change materials for enhanced building energy efficiency and comfort

Because of its vast deposits and slow rate of resource utilization, phosphogypsum (PG), a by-product of the production of phosphate fertilizer, has emerged as a pressing environmental issue. In this study, sodium silicate was blended into PG road stabilizers to change their properties, and the curing method was examined. The ideal mixture was identified by optimizing the ratios of PG, cement (C), silica fume (SF), and slaked lime (SL) using the extreme vertex mixing scheme. Based on this, various ratios of sodium silicate were externally doped, and the changed materials’ strength characteristics, water resistance, and hazardous ion curing impact were all methodically examined.According to the study, doping the PG-cured materials with sodium silicate could greatly increase their strength and water resistance while also successfully enhancing their structural densification and lowering the leaching of harmful ions. These findings showed promising application potential.

In Korea, asbestos-containing waste (ACW) is disposed of in landfills. However, due to the limited landfill capacity and the potential health risks of asbestos contamination, alternative, safer disposal methods are needed. Heat treatment has been suggested as an alternative disposal method for ACW. Therefore, it is necessary to determine the optimal conditions for the thermal decomposition of chrysotile in ACW and reveal the mineralogical composition of heat-treated ACW. In this study, asbestos cement roof (ACR) and asbestos gypsum board (AGB) samples were heat-treated at 600, 700, 800, and 900 °C to identify the optimal heat treatment parameters to eliminate chrysotile fibers. The thermal, chemical, and mineralogical characteristics of the ACW were determined before and after heat treatment using multiple analytical methods. The ACR consisted of chrysotile, calcite, and ettringite, and the AGB consisted of chrysotile, gypsum, and calcite. After heat treatment at 900 °C, the ACR was mainly composed of cement component minerals and lime, while the AGB additionally contained anhydrite. SEM-EDS analysis confirmed the persistence of fibrous minerals in the ACW up to 800 °C. Furthermore, TEM-EDS analysis revealed hollow tubular morphology of chrysotile in the heat-treated ACR at up to 700 °C and in the heat-treated AGB at 600 °C. These results suggest that heat treatment at temperatures of at least 900 °C may be necessary for the complete thermal decomposition of chrysotile in ACW.

Abstract The impact of locally pozzolanic materials on the activation energy of lime cement, with Grade 32.5, was assessed in the fresh and hardened phases of paste and mortar, respectively. The activation energy is used to represent the relationship between the strength gain of concrete over time and temperature sensitivity. Two proportions of mixed pozzolanic materials, metakaolin (MK) and silica fume (SF), were used as a replacement for cement weight. The first was 5% (MK) and 7% (SF); while the second was 10% (MK) and 15% (SF) as a high replacement level. The activation energy of cement was calculated, as per the ASTM C1074 approach, at 5, 20, and 35°C temperatures. The results showed that the rate of strength development (k-value) increased in mixes containing pozzolanic material at all temperatures. The activation energy (E a) increased in all mixes containing pozzolana but decreased with a high replacement level of pozzolana, because of the filler effect during the hydration progress due to the high surface area of these materials, resulting in loss of strength. The results concluded that using the strength development rate (k-value), calculated from ASTM C1074, to estimate the concrete strength at any age is valuable and it is very close to the actual values.

Sustainable development relies on the circularity in the built environment, which, in turn, includes recycling construction and demolition waste and using recycled materials. However, using fine recycled fractions is challenging, especially considering the requirements for new building applications. Yet, producing more widely applied recycled coarse aggregates usually leads to the simultaneous generation of recycled sand fraction, which contains many fines that pose potential problems. This work presents the direct incorporation of concrete and mixed waste-based recycled sand and recycled fines in masonry mortars, on the one hand, as a complete aggregate replacement and, on the other, only replacing the finest aggregate fraction. Such mortars are assessed based on the fresh and hardened mortar properties and are compared to natural aggregate-containing mortars. In the fresh state, the mortars with recycled fines and recycled sand required more mixing water to produce comparable consistency and workability. In a hardened state, mortars with recycled mixed waste sand and fines have demonstrated increased mechanical strength compared to natural aggregate mortars. In contrast, those containing recycled concrete aggregates and fines were inferior in that regard. This indicates the potential of using recycled mixed waste fractions to improve masonry mortar performance, although both types might be important in enhancing the sustainability of masonry construction.

Electrolytic manganese residue (EMR) is a solid waste generated during the production of electrolytic manganese metal through wet metallurgy, accumulating in large quantities and causing significant environment pollution. Due to its high sulfate content, EMR can be utilized to prepare supersulfate cement when combined with Ground Granulated Blast furnace Slag (GGBS). In this process, GGBS serves as the primary raw material, EMR acts as the sulfate activator, and CaO powder, along with trace amounts of cement, functions as the alkali activator. This results in the preparation of CaO-modified electrolytic manganese residue-based supersulfate cement (Abbreviated as “SSC”), facilitating the harmless and resourceful utilization of EMR. This study aims to determine the optimal dosage of CaO as the alkali activator for GGBS in SSC. A comprehensive analysis was conducted on four groups, including a control group. The mass ratio of EMR, GGBS, and cement in SSC was fixed as 35:60:5, and the optimum mixing ratio of lime powder as an external admixture was investigated through mechanical tests and microscopic experiments. The hydration products and mechanism of the cementitious materials were analyzed using X-ray diffraction (XRD), pH measurements, thermogravimetric and differential thermogravimetric analysis (TG-DTG), mercury intrusion porosimetry (MIP), and scanning electron microscopy (SEM). The results indicated that, under the combined influence of trace cement and raw lime powder, EMR effectively activated GGBS. The primary hydration products of the SSC are AFt and hydrated calcium silicate (C-S-H), which contributed to the mechanical strength of the SSC. At a hydration age of 3 days, the optimal CaO blending ratio was found to be 8% by mass of dried EMR. With this ratio, the compressive strength of SSC reached 18.2 MPa, the pore size of hardened slurry was refined, the structure became dense, and hydration products increased. It could be concluded that CaO enhances the early strength of SSC when used as an alkali activator.