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Concrete Strength Evaluation Using Manufactured Sustainable Binary-Cement (SI): New Approach Case Study
Get PDFThe production of sustainable binary cement represents an innovative approach in blended cement manufacturing, aligning with environmental objectives by reducing the reliance on ordinary Portland cement and supporting waste disposal efforts. This study explores the partial replacement of cement with high-fineness powders derived from crushed and ground clay brick (CB) and window glass (WG) waste materials, used at replacement levels of 5%, 10%, and 15%. These materials were processed using a storming machine to achieve the desired particle fineness and incorporated into the cement to create what is referred to as sustainable cement (SI). The resulting binary cement formulations were evaluated and found to comply with the setting time, compressive strength, and chemical specifications outlined in ASTM C595. To further assess their performance, the sustainable cements were tested in concrete mixtures designed for three compressive strength levels—2000 psi, 5000 psi, and 7000 psi—in accordance with ACI 211.1, representing low, medium, and high strength applications, respectively. Two groups of mix designs were developed: MSI-B5, MSI-B10, MSI-B15 (with CB powder replacing 5%, 10%, and 15% of cement), and MSI-G5, MSI-G10, MSI-G15 (with WG powder at the same replacement levels). The results demonstrated notable improvements in compressive strength at the low-strength level. Specifically, cumulative strength increases were recorded as 15.8%, 21.9%, and 13% for MSI-B5, MSI-B10, and MSI-B15, respectively, and 12.2%, 15.5%, and 8.1% for MSI-G5, MSI-G10, and MSI-G15, respectively, when compared to the reference mix. In addition to compressive strength, enhancements in flexural and splitting tensile strengths were also observed, exhibiting a strong correlation with compressive performance. These findings support the potential of sustainable binary cement—utilizing CB and WG powders—as a viable and environmentally friendly alternative in concrete production across varying strength classes
Predictive Modeling of CSH Formation in Cement Materials Based on SEM and EDS Analysis
No full textCalcium silicate hydrate (CSH) formation is a fundamental process required to enhance the density, strength, and durability of cementitious materials. However, there is a gap in the research on the structural, physical, and chemical transformations of CSH. The objectives of this study are to develop a predictive model of CSH formation in cementitious materials and evaluate the effects of gelatin powder (GP), silica fume (MS), ground coffee (SCG), and peanut shell (PS) on CSH formation. Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray Spectroscopy (EDS) apply to the study of the composite cementitious materials. A multiple linear regression model is proposed to predict the changes of key elements, which improved the qualitative and quantitative understanding of the hydration mechanisms. The results show that GP significantly accelerates CSH formation by increasing the calcium and oxygen contents, while MS enhances pozzolanic activity by increasing the availability of silicon, resulting in structural densification. SCG contributes to the increase of carbon and oxygen by acting as a filler, while PS has minimal effect on hydration or crystallization. A regression model relating cement mix design proportions and CSH shows strong correlations between admixtures and chemical changes, particularly for calcium (R²=0.988) and silica (R²=0.985). To fill the existing research gaps, this study goes beyond previous studies, which primarily focused on individual aspects of CSH formation without considering the convergence of structural and chemical analysis
Enhancing Durability in Recycled Concrete: Investigating Chloride Permeability with Recycled Aggregates and Plastic Waste
Get PDFThis study investigates the effects of substituting fine aggregates with recycled plastic in recycled concrete, focusing on chloride penetration, compressive strength, workability, and porosity. Recycled plastic was incorporated at 10% (A10) and 20% (A20) by volume, and properties were evaluated across six mix designs. The control mix without plastic (Mix A) achieved the highest 28-day compressive strength (400 KSC), while A10 and A20 showed reduced strengths of 320 and 255 KSC, respectively. The addition of plastic increased mix porosity, resulting in reduced strength and workability due to diminished cement bonding and lubrication. Chloride ingress was assessed under cyclic wetting–drying exposure using a 3.5% NaCl solution. Results revealed progressive surface chloride accumulation over time. Notably, Mix A showed a 137.96% increase in chloride content at a 0–2 cm depth after 280 days, with Mix A20 exhibiting even higher surface concentrations. Chloride content consistently decreased beyond a 4 cm depth, indicating limited long-term penetration into inner layers. These findings highlight the importance of porosity control in mitigating chloride transport in recycled concrete. A clear relationship between plastic content, increased porosity, and enhanced chloride diffusion was observed. While 10% plastic substitution demonstrated acceptable performance, higher levels significantly compromised durability. The study recommends limiting plastic waste incorporation to 10% by volume and maintaining a concrete cover of at least 8–10 cm over reinforcement to enhance resistance against chloride-induced corrosion. These findings support the controlled reuse of plastic waste in sustainable concrete development, particularly for non-structural or low-exposure applications. Optimizing mix design and incorporating supplementary cementitious materials are suggested to improve long-term durability
Damage Evolution and Failure Mechanism of Segmental Tunnel Lining
No full textThe prevention and treatment of damage in segmental tunnel lining structures are critical issues in maintaining tunnel integrity. Understanding the damage evolution and failure mechanisms of these structures is essential for their effective management. This study establishes refined numerical models for shield tunnel segmental linings, incorporating critical factors such as localized weakening around hand holes, multi-interface contact behavior, and embedded reinforcement. A total strain crack model is employed to accurately simulate the nonlinear behavior of concrete. The analysis focuses on the compression-bending failure behavior of segmental joints under positive bending moments and investigates the failure mechanisms of segmental linings subjected to surcharge loading. The results show that the deformation of segmental joints under bending moments can be divided into three stages: linear elasticity, elastoplasticity, and failure. The failure mechanism involves the progressive expansion and penetration of cracks in the core pressure-bearing area, leading to increased crack width, yielding of bolts and rebars, and eventual failure. The overall instability failure of segmental tunnel linings is caused by local failures in areas of low stiffness (joints, hand holes), exhibiting progressive failure characteristics. This study presents significant originality and practical value. A refined analytical model of shield tunnel structures is developed to capture the millimeter-scale cracking characteristics of segmental concrete linings. The model enables precise analysis of the mechanical response of shield tunnels under external construction-induced loading
The ITB Unit Hydrograph Method: A Novel Approach to User-Defined Unit Hydrograph Development (Part II)
Get PDFThis paper is the second part of a comprehensive two-part series on the ITB Unit Hydrograph (ITB-UH) Method, titled The ITB Unit Hydrograph Method: A Novel Approach to User-Defined Unit Hydrograph Development. Building on the foundational concepts introduced in Part I, this paper delves into advanced applications of the ITB-UH Method, emphasizing its adaptability, calibration capabilities, and real-world utility. The ITB-UH Method introduces novel derivations for the Peak Rate Factor (Kp) and Peak Discharge (Qp), along with a time-step normalization approach that enables flexible adjustments to unit rainfall durations and a systematic calibration process. These innovations significantly enhance the method's versatility and accuracy in modeling flood discharge across diverse hydrological conditions. The practical applicability of the ITB-UH Method is demonstrated through real-world flood discharge calculations in the Pinamula River, located in Buol District, Central Sulawesi Province. Three illustrative examples highlight the method's versatility: (1) analyzing flood hydrographs at a 1-hour time step to showcase its practical applicability for flood management; (2) recalculating flood hydrographs with a finer 0.5-hour time step to demonstrate its adaptability to varying temporal resolutions; and (3) refining model parameters to improve alignment with observed flood hydrographs, underscoring the method's capacity for calibration and optimization. To evaluate the method's performance, robust metrics such as the Nash–Sutcliffe Efficiency (NSE), Percentage Bias (PBIAS), and Index of Agreement (IA) are employed. These metrics confirm the ITB-UH Method's accuracy and reliability, with results consistently aligning closely with observed data. Collectively, the findings underscore the ITB-UH Method's suitability across diverse hydrological settings and its potential to enhance both the verification of existing SUH methods and the development of user-defined hydrographs. By enabling more accurate and effective flood management, the ITB-UH method represents a significant advancement in hydrological modeling, with broad implications for water resource management and infrastructure planning worldwide. Doi: 10.28991/CEJ-2025-011-05-015 Full Text: PD
Using the Kalman Filter with Satellite Altimetry to Estimate the Water Level of Inland Water
No full textThe Euphrates River extends for approximately 2,700 km, making it the longest river in Southwest Asia. Reliable water level measurements are obtained through the integration of an advanced outlier rejection system with Kalman filter technology. This study employs water level data from the Database for Hydrological Time Series over Inland Waters (DAHITI) and validates them using in situ measurements collected from gauging stations along the Euphrates River. To improve the accuracy of water level time series across the study area (Lat: 31.9676, Lon: 44.9306 to Lat: 31.0955, Lon: 46.0942), the research incorporates multibeam altimetry data from Envisat, Jason-2, and Sentinel-3A/B/B. Validation of the altimetry techniques is carried out by comparing DAHITI water level records with in situ measurements and other satellite-based datasets. Both the Kalman filter and Hydroweb methods yield Unbiased Root Mean Square Difference (ubRMSD) values ranging between 0.2961–0.3922 cm and 0.536–0.577 cm, respectively. The Nash-Sutcliffe Efficiency coefficient for DAHITI-derived water levels varies between 0.5971 and 0.9831, while Hydroweb produces values from –0.871 to 0.567. Overall, DAHITI-based altimetry height estimates demonstrate superior accuracy compared to other altimeter datasets in most parts of the Euphrates River, with precision strongly influenced by river topography. The application of Kalman filtering further enhances water level monitoring, particularly in regions characterized by complex inland water structures
Subsurface Mapping and Geotechnical Design for Landslide Mitigation
No full textThe landslide near the PT Molindo Incinerator Unit poses a significant threat to the facility’s structural integrity. Without immediate mitigation measures, the incinerator building is at risk of collapse, potentially impacting adjacent settlements due to cascading structural failures. To reduce the risk of further instability, urgent geophysical investigation is required to characterize the subsurface lithology and assess the groundwater table conditions. A geoelectrical resistivity survey was conducted using the Schlumberger configuration across 8 measurement points along a 100-meter survey line, with 10-meter electrode spacing. The resistivity measurements ranged from 3.30 to 25 Ωm, which were interpreted as clay-rich layers; 26 to 167 Ωm, corresponding to sandy clay; and 167 to 15,944 Ωm, indicating bedrock. The potential slip zone is interpreted at an average depth of 20 to 25 meters, indicated by very low resistivity values with resistivity values between 3.30 and 25 Ωm. Field observations confirmed that the landslide materials predominantly consisted of clay soils, distributed within two distinct layers beneath the incinerator unit. The combined depth of the clay and overlying sandy layers was estimated to reach approximately 20-25 meters from the ground surface. To ensure the effectiveness of structural mitigation, a retaining wall must be designed to extend beyond this depth threshold. Numerical simulations using Slope/W software indicated that soil nailing techniques yielded safety factors ranging from 1.32 to 1.81 under static conditions and 1.22 to 1.43 under dynamic conditions. Predicted deformations ranged from 0.01 to 0.02 meters (static) and 0.02 to 0.03 meters (dynamic). These results suggest that soil nailing is a viable reinforcement method to stabilize slope movements, particularly during periods of high rainfall. Additional recommended mitigation strategies include the installation of surface and subsurface drainage systems to control water flow, constructing retaining structures to serve as physical barriers to soil movement, and using vegetative cover to enhance slope stability
Impact of Water Quality and Sediments on the Riparian Vegetation of Andean Lake
No full textThis study evaluates the quality of water and sediments in a high-altitude Andean lake designated as a RAMSAR wetland of international ecological importance called Guamuéz Lake (Laguna de la Cocha). The analysis focuses on their effects on riparian vegetation, particularly on Schoenoplectus californicus (Bulrush), a keystone species in the lacustrine ecosystem. Water and sediment samples were collected from areas under varying levels of anthropogenic pressure, including zones with and without visible degradation. Results indicate that agricultural runoff, aquaculture, and domestic wastewater discharges are major drivers of spatial and seasonal variability in water quality. Elevated biochemical oxygen demand (BOD5) and chemical oxygen demand (COD) were observed during the rainy season, suggesting increased organic matter input. Sediment analyses showed that impacted areas had higher concentrations of metals such as iron and manganese and significantly elevated microbial loads. Microbiological analysis of sediments revealed a 440% increase in total microbial colonies at impacted sites compared to unaffected ones, with fecal coliforms (FC) and total coliforms (TC) increasing by 191% and 513%, respectively. This suggests that wastewater contamination promotes anaerobic conditions detrimental to S. californicus root systems, possibly contributing to vegetation dieback. The findings underscore the importance of including sediment quality assessments in aquatic ecosystem monitoring, as key indicators of riparian vegetation decline may not be evident through water analysis alone. These results call for integrated and sustainable watershed management practices to mitigate human impact and preserve the ecological integrity of this internationally recognized wetland system
Enhancing Post-Fire Performance of Lightweight RC Slabs Using Expanded Polystyrene and Steel Fibers: An Experimental Study
No full textAggregate significantly influences the mechanical properties of concrete material and has a crucial role in post-fire behavior. This research focuses on investigating the post-fire behavior of a fiber-reinforced one-way slab made from lightweight expanded polystyrene (EPS) aggregate concrete. The experimental study consisted of testing fourteen fiber-reinforced self-compacting concrete (SCC) one-way slabs with EPS as a partial replacement of coarse aggregate. All specimens have identical dimensions of 1800×500×125 mm. The main parameters investigated included fire exposure, EPS replacement ratio, and steel fiber content. The tested specimens were divided into two groups. The first group included seven specimens tested under monotonic static load, whereas the seven specimens of the second group were tested under monotonic static load after being exposed to a steady-state temperature of 700°C for one hour. Following exposure to fire, results revealed a dramatic decrease in the structural performance of the slab specimens, including cracking load, ultimate load, stiffness, absorbed energy, and ductility, especially for the non-fibrous lightweight samples. However, adding EPS beads in the concrete mixture helps in reducing strength degradation due to fire exposure, and the higher the EPS content, the less strength degradation. This result exposed the positive impact of EPS on the structural performance of RC lightweight slabs exposed to fire due to their thermal properties. Moreover, results revealed a significant enhancement in post-fire stiffness, ductility, and absorbed energy of the RC slab due to steel fiber inclusion, showing their constructive impact on the slab performance
Application of Feldspar Sand in Non-Autoclaved Foam Concrete Technology
Get PDFThe aim of this study is to determine the possibility of producing non-autoclaved foam concrete of grade M35 with a density of 900 kg/m³. A distinctive feature of this development is the testing of twin samples from the same batch: some were steamed in a chamber at 90 °C under normal atmospheric pressure, while others were autoclaved at a pressure of 8 bar and a temperature of 170 °C. It was established that ordinary natural feldspar sands with a fineness modulus ranging from 1.43 to 2.45, containing quartz below the standard-regulated levels, can be used in the production of non-autoclaved foam concrete. It is not possible to obtain non-autoclaved D900 foam concrete of grade M35 strength using only cement, sand, and foaming agent. To achieve the specified strength, it is necessary to use coarse sand with a fineness modulus (FM) greater than 3, subjected to short-term grinding to reduce the FM to recommended values, and to additionally introduce sol-gel liquid glass. The novelty lies in the experimental confirmation of the features of strength formation in cellular concrete under both non-autoclaved and autoclaved curing conditions. Comparative tests showed that high strength in cellular concrete is achieved only when a chemical bond forms between the products of cement hydrolysis and hydration with quartz sand grains—conditions made possible through autoclaving