http://hdl.handle.net/10453/148702 2026-07-04T07:03:04Z http://hdl.handle.net/10453/195526 Title: Preparation of self-sensing engineered cementitious composites (ECC) sensor and its sensing performances in concrete column Authors: Han, J; Chen, P; Cai, J; Lai, Z; Pan, J; Song, Z; Li, Z Abstract: Self-sensing cementitious composites offer a promising solution for real-time and accurate structural integrity assessment in structural health monitoring. In this study, parameters of the self-sensing engineered cementitious composites (ECC) sensor were analyzed using ABAQUS/standard solver and a finite-element analysis model was established. Self-sensing ECC sensors were prepared via molding, hydration termination, wire connection and encapsulation. These sensors were then embedded within reinforced concrete columns to examine the column mechanical properties, including bearing capacity, crack development and failure patterns. To evaluate the sensing accuracy, sensor data was compared to strain gauge measurements. Results indicated that a 20 mm cubic sensor with a surface friction coefficient at least 0.6 was optimal and the sensor should be installed inside the matrix. It was observed that the sensor effectively monitored the deformation without affecting the structural integrity. In addition, high sensing accuracy was achieved under low load conditions, however, accuracy decreased as loading increased. 2025-03-15T00:00:00Z http://hdl.handle.net/10453/195525 Title: Utilization of AC impedance spectroscopy (ACIS) for non-destructive damage evaluation of engineered cementitious composites (ECC) after exposure to high temperatures Authors: Ding, B; Xi, X; Han, J; Pan, J; Sui, X; Cai, J Abstract: Engineered cementitious composites (ECC) exhibit excellent tensile ductility and high-temperature resistance, making them ideal for use as fireproof coatings. Despite maintaining their external appearance after high-temperature exposure, ECC may experience significant internal microstructural and mechanical degradation, highlighting the need for non-destructive methods to assess post-fire safety. This study investigates the use of AC impedance spectroscopy (ACIS) for non-destructive damage evaluation of ECC after exposure to high temperatures. The mechanical properties of ECC were first examined after thermal exposure (20°C-600°C). AC impedance measurements (100Hz-5 MHz) were then conducted, utilizing an equivalent circuit model (ECM) for parametric analysis of conductive paths. Thermogravimetric analysis (TG) and X-ray computed tomography (X-CT) were employed to track thermal reactions and extract 3D pore structures for micro-level interpretation. The results confirmed the effectiveness of ACIS in characterizing ECC's damage after exposure to high temperatures, with frequency-dependent impedance changes serving as the key indicators. The ECM [R(C(RC))(RW)] incorporated electrical elements such as interfacial capacitance, charge-transfer impedance, and Warburg impedance, facilitating detailed interpretation of fiber melting and ion migration behaviors. The fitting errors for impedance modulus and phase angle were controlled within 4.93 % and 1.21°, respectively. Above 400°C, ionic migration ceased, and the fiber network transformed into interconnected pore structures, resulting in a marked increase in impedance and deterioration of both compressive strength and tensile properties. These findings highlight the high sensitivity and potential of ACIS for non-destructive applications, offering new insights into ECC's thermal decomposition mechanisms. 2025-04-04T00:00:00Z http://hdl.handle.net/10453/195524 Title: Study on the effect of silica fume dosage on the mechanical properties and chloride ion penetration resistance of ultra-high ductile cementitious composites (UHDCC) Authors: Sui, X; Yang, J; Huang, Y; Lu, C; Wang, Q; Zhuang, K; Xu, Y; Zhou, Y; Cai, J Abstract: The development of building materials that balance toughness and durability is critical for advancing infrastructure resilience. This study investigates the effects of silica fume (SF) admixture on the mechanical properties and chloride ion penetration resistance of ultra-high-ductility cementitious composites (UHDCC). UHDCC specimens with varying SF contents were prepared and subjected to mechanical property tests, chloride ion penetration resistance tests, and micro-morphological analysis to elucidate performance enhancements and underlying mechanisms. The results indicate that the incorporation of 10 % SF significantly improves the mechanical properties. Compared to the specimens without SF, the peak tensile stress and the corresponding strain increased by 332.64 % and 145.63 %, respectively. Furthermore, the non-stationary chloride migration coefficient was reduced to 1.20 × 10⁻¹² m²/s, which is 66.7 % of that of specimens without SF. These findings underscore the effectiveness of SF in enhancing UHDCC's structural and durability properties, providing valuable insights for advanced material design in infrastructure applications. 2025-08-01T00:00:00Z http://hdl.handle.net/10453/195523 Title: Shear behavior of reinforced one-part geopolymer concrete beams Authors: Wan, S; Zong, Z; Lin, Y; Shi, H; Yuan, Y; Ding, B; Cai, J Abstract: Geopolymers, emerging as a novel low-carbon cementitious material, have garnered growing attention in recent years. Notably, the recently developed “one-part geopolymer” (OPG) has shown mechanical properties and durability comparable to those of ordinary Portland cement (OPC). However, the mechanical behavior of one-part geopolymer concrete (OPGC) structural members remains insufficiently understood, which limits its engineering application. This study explores the shear behavior of reinforced OPGC beams. Ten beams were tested under four-point loading to examine their damage modes and evaluate the effects of shear span ratio and stirrup ratio, with an OPC concrete (OPCC) beam considered a counterpart for comparison. Test results revealed that the shear capacity of OPGC beams decreases as the shear span ratio increases. OPGC beams with low stirrup ratios exhibit brittle shear failure, whereas this can be effectively mitigated by increasing the stirrup ratio. OPGC beams demonstrated slightly better load-carrying capacity and ductility compared to OPCC beams. In addition, this study evaluated the applicability of theoretical shear capacity formulas from existing structural design codes in China, the UK, the United States, and Japan for the shear design of OPGC beams. The results revealed that all the design codes were overall applicable to the shear design of OPGC beams. Finally, the overall performance of OPGC and OPCC beams was evaluated and compared by considering environmental and economic indicators. This study offers valuable insights for the design and analysis of OPGC beams subjected to shear. 2025-10-01T00:00:00Z