Rice husk ash-based sodium silicate and NaOH were combined to activate waste glass powder as the sole precursor, producing rice husk ash-based sodium silicate-activated glass powder (RAGP) binders. Three activator formulations with nominal moduli of 1.0, 1.5, and 2.0 and approximately constant Na2O equivalents were evaluated at 7 and 28 d by compressive strength testing, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). At 7 d, compressive strength decreased from 31.4 to 29.6 MPa as the nominal modulus increased. At 28 d, RAGP-1.5 achieved the highest strength (39.6 MPa), a 31.1
Viscoelastic elastomers are selected for the same dual mechanical character, elastic energy storage combined with viscous energy dissipation, that makes their long-term performance difficult to predict, since both the elastic and dissipative halves of that response can drift independently, and in different directions, as the material ages. This review synthesizes natural- and accelerated-aging literature across five elastomer families (NBR, EPDM, HNBR/FKM/CR/ACM, SBR/NR, and silicone) and four property domains, mechanical, dynamic-mechanical/viscoelastic, thermal-kinetic, and modal damping/vibration, to evaluate qualitatively, rather than through a quantitative meta-analysis, how consistently current lifetime-prediction methods capture real degradation behavior. Single-mechanism Arrhenius extrapolation remains the dominant shelf-life estimation approach, but isoconversional methods (Ozawa-Flynn-Wall, Kissinger-Akahira-Sunose) and the related, conversion-independent Kissinger method frequently return activation energies that vary with conversion, and diffusion-limited-oxidation theory explains why thin, high-temperature accelerated specimens can diverge systematically from thick, lower-temperature service components. Cross-material comparisons show that ranking by activation energy alone is an unreliable proxy for predicted service life. Damping and vibration data, though comparatively sparse, reveal that per-mode damping degradation is non-uniform, with higher structural modes eroding progressively faster than the fundamental mode in the single dataset available, a pattern with direct implications for isolator and damper design life. Emerging physics-informed machine-learning approaches show promise as a data-driven correction layer on classical kinetic models, though cross-material external validation and formal uncertainty quantification remain largely unaddressed. Five specific research gaps are identified, several of them evidenced most directly by a single, deeply characterized anchor case rather than confirmed field-wide, and a minimal reporting framework is proposed to make future studies more directly comparable.
Curing environment is a procedure that could substantially modify the strength parameters of soils. This study investigated the time-dependent mechanical response of sand-cement columns under laboratory storage and natural outdoor exposure. The investigated sands comprised Ottawa Sand and four Kermanshah River Sand samples (KRSS#6, KRSS#1, KRSS#1a, and KRSS#1b). The principal specimens contained 12.1 g / cm^3 ) at a water-to-cement ratio of 0.5 and were initially cured for 7 days under laboratory conditions. Subsequently, specimens were retained in the laboratory or transferred to the natural outdoor environment and evaluated at 1, 7, 90, and 900 days. Slow loading was defined as a stepwise sustained-load creep test, with 2 kg load increments maintained for 24 h at each step, whereas rapid unconfined compression was conducted at a controlled displacement rate of 0.5 mm /min. The measured creep failure stresses varied with sand type, conditioning time, and exposure environment, with a maximum of 4998 kPa for KRSS#1 after 900 days of natural outdoor exposure. At 900 days under natural exposure, the creep failure stress exceeded the corresponding rapid-test strength for the investigated columns, with the maximum observed ratio of 4.01 occurring for KRSS#6. The creep secant modulus ( E_𝑐𝑟𝑒𝑒𝑝 ) also exhibited sand-dependent, non-monotonic evolution, ranging from 730 to 5100 kPa at 900 days, depending on the sand type and exposure conditions. Second-order empirical relationships provided coefficients of determination of 0.97 and 0.98 for the rapid and slow responses, respectively. The results demonstrate that both time and exposure environment should be considered when assessing the long-term mechanical performance of cement-stabilized sand columns. Accordingly, laboratory experiments may underestimate in situ resilience if the effects of the curing environment are not properly considered.
Reducing cement consumption without compromising compressive strength is essential for developing more sustainable cemented paste backfill. This study explored the use of carbonated water to reduce cement demand in cement–fly ash backfill mixtures. The effects of CO2 dosage, reaction time, and subsequent slurry stirring duration on 3- and 7-day uniaxial compressive strength (UCS) were investigated, followed by an evaluation of achievable cement reductions under different treatment conditions. At a CO2 injection dosage of 1 wt.
