The utilization of mining wastes as aluminosilicate precursors in geopolymer production offers a promising approach for sustainable waste management and the development of alternative binder systems. This study investigates the potential use of copper mine tailings (CT) as a precursor material in geopolymer mortar production. Raw CT and thermally activated CT calcined at 850 degrees C (CCT) were used either as sole binders or in binary combinations with micro silica (MS), ground granulated blast furnace slag (GGBFS), and roof tile powder (RTP). A 12 Molar Sodium hydroxide (NaOH) solution was employed as the alkaline activator. The results showed that raw CT exhibited limited reactivity when used alone, resulting in compressive strengths of 2.16 MPa and 3.11 MPa at 1 and 28 days, respectively. Calcination improved the alkali-activation performance of CT, increasing the compressive strength of the CCT-based reference mixture by 151% at 1 day and 104% at 28 days compared with raw CT. The flow diameter values of the mixtures ranged between 100 and 130 mm, and binary binder systems generally improved workability. Among all mixtures, the CC50-G50 mixture, containing 50% CCT and 50% GGBFS, achieved the highest 28-day compressive strength of 22.11 MPa, indicating the beneficial role of calcium-rich GGBFS in strength development. The CC50-S50 mixture also showed improved performance, reaching 16.20 MPa at 28 days. Ultrasonic pulse velocity (UPV) results supported the positive influence of calcination and secondary binder incorporation on matrix compactness. Scanning electron microscopy-Energy-dispersive X-ray spectroscopy (SEM-EDS) analyses indicated that the improved mechanical performance of the GGBFS-containing mixture was associated with a denser microstructure, fewer visible cracks, and the formation of calcium-containing aluminosilicate gel phases. In particular, the relatively balanced Si/Al ratio and higher Ca/Si ratio of the CC50-G50 mixture were associated with enhanced gel formation and strength development. Overall, the direct use of raw copper mine tailings resulted in limited mechanical performance; however, calcination combined with suitable secondary binders, especially GGBFS, significantly improved the potential of CT-based materials for sustainable geopolymer binder production.
This paper details a laboratory investigation into how non-plastic fines content influences the monotonic and cyclic liquefaction potential of sandy soil samples. The study involved conducting monotonic and cyclic triaxial tests on reconstituted saturated sand samples with fines content varying from 0 to 25% for the monotonic tests and from 0 to 20% for the cyclic tests. All tests were performed under a confining pressure of 100 kPa and with a relative density of 65%. This paper is divided into two sections. The first section describes the properties of the soils used in the study, while the second section analyzes how non-plastic fines content affects the monotonic and cyclic behavior of sand-silt mixtures. The results from the monotonic tests show that the liquefaction potential of the mixtures decreases as the fines content increases. The results of the cyclic tests indicate that higher fines content accelerates the liquefaction process at the tested amplitudes, while the liquefaction resistance decreases as the loading amplitude increases. The reduction in liquefaction resistance for Rass sand-silt mixtures is notably significant at lower cyclic stress ratios, cyclic stress ratio (CSR) = 0.15 and 0.25.
Utilization of Environmental product declarations of different brands of the same construction material may end up with diverse environmental impact results. Aforementioned variability is not thoroughly investigated in building level in the literature. This study addresses this literature gap by conducting uncertainty analyses on two different types of structures; residential and university buildings by Monte-Carlo Simulation (MCS). The analyses were carried out based on embodied carbon (EC) and embodied energy (EE) values obtained from Environmental Product Declaration (EPD) documents. To conduct the sensitivity analysis, 287 EPD documents related to construction materials were collected; 242 of these were used for university buildings and 177 for residential buildings. The residential building consists of materials such as reinforced concrete frame system, aerated concrete walls, paint, PVC door and window frames, as well as tile roof. The university building consists of materials such as terrace roof, aluminum facade, suspended ceiling, and reinforced concrete frame structure. The collected EPD documents are randomly assigned to the corresponding construction materials. The coefficients of variation for the university building are found to be 11.58% for EE and 8.86% for EC, while for the residential building they are 11.10% for EE and 8.9% for EC. The correlation between EE and EC were computed as 0.7312 for educational and 0.6623 for residential buildings, respectively. The analysis results demonstrated 2 outputs; first, the computed environmental impact values may deviate within 10% based on the utilized EPD documents and second, EE and EC are positively correlated.
Carbide residue (CR) is one of the industrial byproducts treated as industrial waste that has not been fully utilized. Historically, numerous developed countries have implemented innovative approaches to utilize carbide residue as a construction material. However, information regarding the utilization of carbide residue as a construction material in Indonesia remains limited. Therefore, this study aims to perform a preliminary investigation into the properties of carbide residue that could be utilized in mortar manufacture. As supplementary materials, carbide residue was utilized in this investigation to enhance the mechanical and physical engineering properties of hardened mortar. Laboratory tests were conducted to investigate several engineering properties of mortar, including the slump flow of fresh mortar, density, water absorption, porosity, compressive strength, splitting tensile strength, and flexural strength of hardened mortar. This study is divided into two main series. Series 1 employs carbide residue at different concentrations of 10%, 15%, and 20% as a cement replacement material. While series 2 incorporates carbide residue at proportions of 20%, 30%, and 40% as a fine aggregate (sand river) replacement material. Based on this experiment, fresh properties (as determined by the slump flow test) decrease with increasing amounts of carbide residue as a cement and sand substitute. To ensure that the water-to-binder ratio is sufficient, conducting early studies on the water requirements for mortar containing carbide residue as a partial replacement material is essential. The results indicate that 10% carbide residue substituted for cement produces the most enhanced mechanical properties. Meanwhile, it was shown that 40% carbide residue generated the most ideal mechanical properties when used as a substitute for sand.
Hot Mix Asphalts (HMA) may lose their stiffness over time due to traffic loads and environmental effects, leading to structural deformations. The Indirect Tensile Stiffness Modulus (ITSM) test, which is commonly used to determine such properties, requires coring and measurements conducted in laboratory environments using specialized equipment. Therefore, it is both costly and damaging to the pavement structure. This situation necessitates the investigation of faster, more economical, and non-destructive alternative methods. In this study, statistical and artificial intelligence-based relationships between ITSM and various non-destructive testing (NDT) methods (PQI, NDG, LWD, UPV, BP) were examined. The fieldwork was carried out on a 16 km section of the highway between Antalya and Burdur in Turkey. A total of 80 core samples were taken from 20 different locations at one-year intervals, and various non-destructive tests were also performed at the same points. The ITSM results obtained from the core samples were estimated using the non-destructive test data collected from the field. Both classical correlation analyses and Artificial Neural Network (ANN) models for multivariate prediction were employed in the analyses. The findings revealed that certain non-destructive test methods could estimate ITSM values with high accuracy. In particular, data obtained from LWD and UPV devices showed strong linear relationships with ITSM, yielding correlation coefficients above r>0.75 in single-variable correlation analyses. Among the ANN models developed in the study, the most successful model, M6, was structured using all non-destructive test data collectively. This model demonstrated a remarkable performance with an R-2 value of 91.18% for ITSM prediction. On the other hand, models based on individual test methods were observed to have relatively limited prediction success, generally ranging between 58% and 66%.
