The present study was developed to study the engineering properties of polyethylene terephthalate (PET) waste fibres reinforced self-compacting concrete (SCC). The PET fibres were depolymerised by glycolysis to produce an unsaturated polyester resin, which was then used to prepare PET fibre-reinforced self-compacting concrete (PET-FSCC). The present work supports the transition to circular economy principles in the construction industry by valorising plastic waste into avalue-added construction material, thus contributing to the reduction of environmental pollution and the development of sustainable infrastructures. Two fibre geometries (wavy (WPF) and linear (LPF)) and three fibre lengths (35 mm, 40 mm, 50 mm) were studied at volumetric fibre ratios (Vf) ranging from 0.3% to 1.2%. This led to thirty experimental mix designs. The fresh state performance was tested by slump flow, T50, V-funnel and L-box tests and the compressive strength, flexural strength, and modulus of elasticity were examined at 7, 28 and 90 days. The experimental results show that an increase in the fibre length and Vf gradually reduces the workability of fresh SCC and significantly enhances the flexural strength and the modulus of elasticity (up to around 30% and 22.5% respectively at optimal fibre contents). The compressive strength decreased moderately by 3.7 to 5.9% with increasing Vf. The best performance was achieved at Vf = 0.8% for 35 mm fibres and at Vf = 0.5% and 0.3% for 0 mm and 50 mm fibres, respectively. This study has practical implications in that post-consumer PET waste can be used as a macro-fibre reinforcement in SCC and has direct applications in prefabricated elements, floor slabs, tunnel linings, fa & ccedil;ade panels and eco-efficient building components.
The search for efficient and sustainable airport pavement solutions has been ongoing, driven by the need for more durable pavements and fewer restorations. Despite advances, many runway interventions occur due to mismatches in structural support capacity and load levels, as well as functional issues. As a result, milling deteriorated pavement coating layers generates considerable amounts of RAP (Reclaimed Asphalt Pavement). RAP has demonstrated positive results when incorporated into new pavements, primarily in highway paving, and supports both economic and sustainability goals. This study analyzes the structural performance of airport pavements where the coating layer was replaced with recycled asphalt mixtures containing RAP, in lieu of conventional asphalt concrete. Experimental and computational analyses were conducted, including back-calculation of pavement structures at three aerodromes, and then proposing and evaluating new pavement sections mechanically. The design preserved existing granular layers and replaced only the coating layer with a recycled RAP mixture, followed by a seal coat to reduce weathering risk. The mixtures were hot mixed with 100% RAP and a recycling agent. Results showed superior structural responses for the new sections, with a significant increase in the Pavement Classification Rating (PCR). This supports the viability of using RAP in airport pavements and its environmental benefits from reusing residue.
In recent days, the corrosion of steel reinforcement has emerged as a significant concern for Civil engineers in the construction industry. As a result, considerable attention has been directed toward developing methods to predict the service life of reinforced concrete structures. Corrosion often remains undetectable until visible signs such as cracking or delamination appear. To deduce this, electrochemical methods are traditionally utilized to observe its development. Among these, the half-cell potential measurement technique is extensively applied to evaluate the possibility of corrosion. This research develops a method for determining the probability of steel rod corrosion using the half-cell potential technique. The evaluation applied a galvanostatic method on 10 mm, 12 mm, and 16 mm in diameter steel rods. Corrosion potential (Ecorr) and concrete resistivity (rho) measurements were recorded at every point on a pre-determined interval. A predictive model in SPSS was built to forecast each rod corrosion rate and ultimate tensile strength. The experimental results corresponded closely with the predicted values, with percentage differences of 3.4%, 2.6%, and 0.9% for the 10 mm, 12 mm, and 16 mm rods, respectively. These observations validate that electrical resistivity is a most appropriate and good indicator for forecasting steel reinforcement corrosion rate and tensile strength.
This study investigates the fresh, mechanical, durability, and microstructural performance of self-compacting concrete (SCC) incorporating alkali-activated fly ash (FFA), glass powder (GGP), and their hybrid combinations with ordinary cement (OC). The aim is to evaluate the feasibility of sustainable SCC systems under low-molarity NaOH activation (1 M) while maintaining structural performance requirements. Results show that hybrid SCC mixtures achieved slump flow values between 495-640 mm, with T50 times ranging from 0.8 to 3.6 s, indicating acceptable flowability and stability. The 50OC-50FFA mixture exhibited a compressive strength reduction of 10-18%, while the 50OC-50GGP system showed a higher reduction of 15-25% compared to conventional SCC (100OC). Chloride ion permeability increased by 35-50% in 100FFA, whereas hybrid systems showed improved resistance with intermediate charge values, maintaining structural durability requirements. Freeze-thaw testing revealed durability factors exceeding 100% retention for hybrid mixes, while 100FFA failed after approximately 75 cycles. SEM and FTIR analyses confirmed that FFA promotes a denser geopolymeric network, whereas GGP exhibits limited reactivity under low alkalinity, behaving primarily as a filler. The study demonstrates that hybrid SCC systems provide a balanced trade-off between sustainability and performance, while also highlighting the limitations of low-alkali fly ash activation. Overall, the findings support the development of environmentally efficient SCC systems with improved durability and acceptable mechanical properties.
In order to investigate the efficacy of the tung oil (OT), which has self-healing properties, in the prevention of pathologies related to High-Performance Concrete (HPC), this work monitored the compression strength (fc) and modulus of elasticity (E) of an HPC which contained different OT: superplasticizer (SP) ratios, as well as its hydration kinetics (by nuclear magnetic resonance, NMR). The analysis of variance (ANOVA) allowed us to evaluate the impact of OT on fc, comparing average variations between different treatments. The control sample, containing 4% SP and 0 g of OT, achieved an average fc of 74.44 MPa and E of 42.81 GPa. The insertion of 2 g of OT into the control sample (4% SP 2 g OT) promoted an increase in fc and E of 2.6 MPa and 0.46 GPa, respectively. The use of 3% SP and 2 g of OT caused an increase of 8.53 MPa in its fc and 1.49 GPa in E. ANOVA demonstrated that OT is the most important regulating admixture within the concrete matrix, superior to SP by 3.6 times. Through NMR curves of spin-lattice relaxation time (T1) in function of the hydration of samples containing: 4% of SP and 0 g of OT; 4% of SP and 2 g of OT and 3% of SP and 2 g of OT were obtained. These samples have shown decreased exponential profile, indicating an increase in the gel-space (porous) ratio of HPC and a reduction of evaporable water in the hydration process. The data obtained provided important insights as to how promising OT can be in the partial replacement of superplasticizer to promote a more resistant, ecologic and sustainable HPC, with lower production costs. This reinforces the One Health approach, which includes collective actions against disasters promoted by climate changes.
