Green concrete composites production comprising metalized plastic waste fibers and palm oil fuel ash

Amongst the potential solutions to a cleaner environment is to minimize the consumption of non-biodegradable materials and to reduce wastes. The generation and disposal of waste plastics cause severe impacts on the environment. The utilization of solid waste in the sustainable constructions has concerned much attention due to the lower cost of wastes along with saving a necessary place of landfills. In this paper, the feasibility of metalized plastic waste (MPW) fibers and palm oil fuel ash (POFA) in the production of concrete composites was investigated by assessing the mechanical properties and ultrasonic pulse velocity. Six concrete mixes containing MPW fibers varying from 0 to 1.25% with a length of 20 mm were made of ordinary Portland cement (OPC). A different six concrete mixtures with the same fiber content were made, where 20% POFA substituted OPC. The results show that MPW fibers, together with POFA reduced the workability of concretes. It has also been found that by adding MPW fibers to the concrete mixtures, the compressive strength decreased for both OPC and POFA mixes at the early ages. Though at the curing period of 91 days, the mixes contain POFA attained compressive strength higher than those of OPC mixes. The mixture of MPW fibers and POFA subsequently enhanced the tensile and flexural strengths, thereby increasing the ductility. The study revealed that the MPW fibers are potential to be used in sustainable concrete by improving the mechanical properties

Properties and applications of FRP in strengthening RC structures: a review

In civil and structural engineering, building structures with robust stability and durability using sustainable materials is challenging. The current technological means and materials cannot decrease weight, enlarge spans, or construct slender structures, thus inspiring the exploration for valuable composite materials. Fiber reinforced polymer (FRP) features high-strength and lightweight properties. Using FRP motivates civil engineers to strengthen existing RC structures and repair any deterioration. With FRP, a system that can resist natural disasters, such as earthquakes, strong storms, and floods, can be developed. However, deterioration of structures has become a critical issue in modern construction industries worldwide. This paper reviews the FRP design, matrix, material properties, applications, and serviceability performance. This literature review also aims to provide a comprehensive insight into the integrated applications of FRP composite materials for improving the techniques of rehabilitation, comprising the applications toward the repair, strengthening, and retrofit of concrete structures in the construction industry today

Analytical mechanics solution for measuring the deflection of strengthened RC beams using FRP plates

Partial-interaction due to sliding between the steel bars, adhesively attached FRP plates and their bordering concrete surface, accompanied with the detachment of the FRP plates due to intermediate crack (IC) debonding make the deflection of strengthened RC beams difficult to anticipate. Previous research and design rules on determining the deflection of strengthened RC beams using FRP plates have opted for a full-interaction moment-curvature design technique where the deflection was measured by either deriving average effective moment of inertia and using elastic deflection equations or integrating the curvature along the beam’s length. Therefore, IC deboning of the plate and the slip resulting from the formation and broadening of new cracks were not directly considered. In this study, a partial-interaction moment-rotation analysis of an adhesively plated beam segment was used to derive analytical equations for the rotation of individual crack faces. The analytical expressions were used to compute the rotation at a crack for a given moment; subsequently, the influence of each crack to the midspan deflection of the RC beams was calculated. As for the uncracked region of the beam, the deflection contribution was measured by integrating the curvature over the uncracked span. The deflection results from the mechanics solution seem to compare well with experimental results. The analytical mechanics solution accounts for the partial-interaction between the steel bars, externally bonded FRP plate and their bordering concrete surface, and also the detachment of the external plate through IC debonding. Further, due to its generic nature and non-reliance on empirical data, the mechanics solution can be adopted to forecast the deflection of strengthened RC beams with novel types of reinforcement materials

Effects of waste ceramic as cement and fine aggregate on durability performance of sustainable mortar

In the last 3 decades, the attention in consuming substitute materials such as solid wastes in construction has grown continuously. An extensive amount of waste ceramic is being generated all around the world. These wastes are mostly sent to the landfill without considering recycling option. Such waste ceramic in the powder and fine particle forms has good potential in the infrastructure industry. In this study, the strength and durability properties of a mortar comprising ceramic waste powder as supplementary cementing material and ceramic particles were investigated. Properties studied include workability, compressive and tensile strengths, chloride and sulfate resistance. The effect of waste ceramic was also assessed by using scanning electron microscopy and X-ray diffraction analysis. It was observed that the utilization of waste ceramic in both forms of binder and fine aggregate significantly improved the compressive and splitting tensile strengths and higher resistance against chloride and sulfate attacks. The microstructure of the mortar was further enhanced by replacing ceramic waste powder and fine aggregates. It, therefore, caused in the higher crystalline formation and reduction in porosity and cracks in addition to eliminating the spalling behavior of mortar specimens exposed to chloride and sulfate attacks

Waste metalized film food packaging as low cost and eco-friendly fibrous materials in the production of sustainable and green concrete composites

Among the potential solutions to a cleaner environment is to decrease the consumption of non-biodegradable materials and to reduce wastes. The generation and disposal of waste plastics cause severe impacts on the environment. The utilization of solid waste in the sustainable constructions has concerned much attention due to the lower cost of wastes along with saving a necessary place of landfills. The current paper investigates the feasibility of utilizing waste metalized plastic (WMP) fibers used for food packaging and palm oil fuel ash (POFA) in concrete in terms of mechanical and transport properties. Six fiber dosages of 0–1.25% were used for ordinary Portland cement (OPC) mixtures. In addition, the same dosages of fibers were used in mixes with 20% POFA. The results show that WMP fibers, together with POFA, reduced the workability of concretes. It has also been found that by adding WMP fibers to the concrete mixtures, the compressive strength decreased for both OPC and POFA mixes at an early age. Though at the longer curing time, say 91 days, the mixes contain POFA attained compressive strength higher than those of OPC mixes. The mixture of WMP fibers and POFA subsequently enhanced the tensile and flexural strengths, thereby increasing the ductility as well as the higher post-failure compressive strength of concrete. Besides, water absorption, sorptivity, and chloride penetration depth were reduced for concrete mixes incorporating WMP fibers up to 0.75% and 20% POFA. The study revealed that the WMP fibers are potential to be used in sustainable concrete by developing transport and mechanical properties

RC beam strengthening using hinge and anchorage approach

Retrofitting of existing structures using adhesively bonded plates has been a major growth area in civil engineering and has gained well-deserved popularity over the past few years. This strengthening technique is in line with sustainable practices in construction and can be used to preserve eminent structures of historical or cultural values. This study aims to present an ideal design model for strengthening reinforced concrete elements using the hinge and anchorage design philosophies for retrofitting and plating existing structures. This includes a check on the intermediate crack (IC), critical diagonal crack (CDC), and plate end (PE) debonding mechanisms. The results of a theoretical model for an FRP plated reinforced concrete beam element were presented, and the findings showed that plating increased the shear at the datum point to cause a diagonal crack by 46.7%. The increase in moment capacity due to plating the hogging region was 64.3% while allowing for 30% moment redistribution from the sagging region to the hogging region. The accompanying increase in uniformly distributed load due to 30% moment redistribution was 42.8%. The results of the theoretical model were compared with previous design models for IC debonding to which it has been shown that following the anchorage approach, a higher strain in the plate may be allowed as compared to the hinge approach. In addition to the theoretical model presented, analysis on an FRP plated RC beam and slab were also presented to show the effect of different plate widths on the moment capacity and PE moment capacity

Structural behavior of out-of-plane loaded precast lightweight EPS-foam concrete C-shaped slabs

This study aimed to develop optimum lightweight expanded polystyrene foam (LEPSF) concrete with a compressive strength of 35 MPa at a density of 1980 kg/m3, to produce precast LEPSF concrete C-shaped slabs with different parameters. LEPSF beads and quarry dust were used as partial replacements for coarse and fine aggregates at different percentages of (15%, 22.5%, and 30%) and (7.5%, 15%, and 22.5%), respectively. From the findings of this investigation, it was noticed that the use of LEPSF beads resulted in acceptable early age strength; however, a reduction in strength was observed at a mature age. Meanwhile, the use of quarry dust improved the compressive strength of LEPSF concrete by more than 30% compared to the mixtures with EPS alone. Totally, 256 samples were prepared to examine the physical and engineering properties of LEPSF concrete mixtures. Results revealed that the deflection of the full-scale LEPSF concrete C-shaped slabs was 31.5%–45.7% more than that recorded in comparable normal concrete slabs. Meanwhile, results have shown that the ductility of the precast LEPSF concrete C-shaped slabs improved in comparison to the normal concrete samples and they also exhibited 20% reduction in the self-weight. It was also seen that precast LEPSF concrete C-shaped slabs give more warning time before failure occurs. As such, it was concluded that the developed precast LEPSF concrete C-shaped slabs have a significant potential to be adopted in flooring systems of modern buildings today

Flexural strength of FRP plated RC beams using a partial-interaction displacement-based approach

esigning FRP plated RC beams using full-interaction moment-curvature analysis would often suggest that the RC structure is brittle with debonding often occurring prior to yielding of the reinforcement steel. For that reason, researchers have looked into a displacement-based approach that takes into account the member debonding mechanism. The force in the plate within the debonded region was assumed to remain at the intermediate crack debonding force, PIC, and the ultimate strength was determined by considering compatibility of displacements along the member length. However, from laboratory testing, it is seen that the force in the externally bonded FRP plate keeps building up until failure occurs. Therefore, in this study, an extension to the displacement-based approach developed by previous researchers for FRP plated beams is presented where the residual bondstress of the plate within the debonded region is incorporated in the analysis. This is achieved by adopting a bond-slip model with a residual shear component that allows for the force in the plate to increase beyond PIC. The ultimate strength of the FRP plated beams is determined when the plate displacement matches that of the concrete near the plate end. A comparison with the experimental results of seven adhesively plated beams shows that incorporating the residual bondstress of the externally bonded plate yields significant improvement in accuracy and give better correlation with experimental findings

The clinico-pathologic profile of primary and recurrent orbital/periorbital plexiform neurofibromas (OPPN)

To evaluate and compare the clinical and histopathological profile of primary and recurrent orbital-periorbital plexiform neurofibromas (OPPN) in patients with neurofibromatosis type 1. We retrospectively evaluated 43 primary or recurrent neurofibroma (NF) specimens from 26 patients (2002 to 2018) at the King Khaled Eye Specialist Hospital, Saudi Arabia. Demographics, clinical presentation, and surgical intervention data were collected. Histopathological specimens were studied with hematoxylin-eosin, Alcian blue, and immunohistochemical markers; S-100, CD44, CD117, smooth muscle actin (SMA), neurofilament, and Ki-67. Of the 43 NFs specimens, 20 were primary and 23 recurrent tumors. For primary NF, the ratio of plexiform to the diffuse type was 13:7, however in recurrent tumors was 3:8 after the first recurrence, and 1:5 after multiple recurrences. Of the 17 patients with primary tumors that had paired recurrent tumors, 12/17 (70.6%) primary NFs were plexiform and 5/17 (29.4%) were diffuse. However, when tumors recurred, 13/17 tumors (76.5%) were diffuse and only 4/17 tumors (23.5%) had a plexiform pattern. The odds of a tumor having a diffuse pattern in recurrent NF was significantly higher than the plexiform pattern [OR = 7.8 (95% confidence interval 1.69:36.1) P = 0.008]. Primary plexiform NFs underwent an excision at a significantly younger age than the diffuse type. Recurrent NFs had significantly higher CD44, CD117, and neurofilament labeling (P = 0.02, P = 0.01 and P<0.001 respectively) but had significantly decreased Alcian blue, and S-100 labeling (P = 0.03, and P = 0.02 respectively) compared to primary tumors. SMA and Ki-67 proliferation index were not different between primary and recurrent NFs (P = 0.86, and P = 0.3 respectively). There appears to be a high risk for primary plexiform NFs to develop a diffuse histologic pattern when they recur. Immunohistochemical staining suggests a role of mast cells (CD117) and expression of infiltration makers (CD44) in the transformation of plexiform tumors to the diffuse phenotype