Background and Aim: Considering flexural strength of Fiber-Reinforced composites (FRC) and also the role of conservative cavities in protecting sound tissue of abutments, the aim of this study was to evaluate the fracture resistance of these bridges by handmade samples in vitro.Materials and Methods: In this experimental in vitro study, 44 sound newly extracted teeth were used to make 22 fixed inlay bridges including 11 three unit anterior upper inlay bridges substituting clinical model of upper central and 11 three unit posterior lower inlay bridges substituting clinical model of lower first molar.Specimens were prepared with FRC and mounted with artificial PDL in acryl. Cases were exposed to final load by using Universal Testing Machine (Instron 1195) with the speed of 1 mm/min. Statistical analysis was performed by Kolmogorov- Smirnov, independent sample T and Kaplan-Meier tests with p<0.05 as the level of significance.Results: Based on the statistical tests, the 95% confidence interval of mean was 450-562 N in anterior and 1473- 1761 N in posterior area. Fracture strength was high in the studied groups. Fractures in both groups occurred on composite facing, and the framework remained intact. The highest percentage of fracture in posterior teeth was in the middle of pontic towards the distal connector and in the anterior teeth in the lateral connector, between central pontic and lateral abutment. Using the independent sample T test a significant statistical difference was observed between two groups (P<0.001). The fracture resistance of anterior samples was lower than the posterior ones.Conclusion: Based on the results of this study regarding the high fracture resistance in both areas FRC inlay bridges could be recommended for upper anterior and lower posterior teeth in clinical dentistry certainly more studies are needed to ascertain this treatment option.

Porous Asphalt Mixture is a type of Asphalt Mixture with good drainage. However, it has poor tensile performance and durability. Crushed basalt Fibers (CBF) have been proven to be an effective additive to improve the mechanical performance and fatigue of Asphalt Mixtures, but little attention has been paid to porous Asphalt Mixtures. In this research, the effect of crushed basalt Fibers with different lengths (non-Fibers, 3 mm, 6 mm, 9 mm and 12 mm) and contents (3% and 4%) on the performance of porous Asphalt Mixture is investigated. A series of tests were performed to determine the optimal Fiber length and percentage, including the shedding test, the canta abrasion test, the freeze-thaw split tensile test, the wheel groove test, the low temperature cracking resistance test, and the four-point bending beam test. After that, indirect tensile tests were conducted at different temperatures to investigate the tensile strength properties of porous Asphalt Mixtures with optimal Fiber length and percentage. The results show that the addition of crushed basalt Fibers can generally improve the performance of the porous Asphalt Mixture because the crushed basalt Fibers form a three-dimensional network structure in the porous Asphalt Mixture.

This research evaluates the effect of recycled polyethylene terephthalate (PET) Fibers on the fatigue properties of hot mix Asphalt. Based on micro-structural analysis, Fiber contents were taken into account as equal to 0.5, 1.0, 1.5 and 2.0% by weight of bitumen. Fibers used with two lengths of 1 and 2 cm and an average diameter of 30 mm. For comparison, crumb PET with the particle size of 0.425-1.180 mm was used in two contents of 1 and 2% by weight of bitumen. Slab specimens of the reference and Reinforced mixes were compacted by laboratory roller compactor to achieve 4±0.2 % air void. After that, the specimens were removed from the mold and sawed to obtain beam-shaped specimens. Then, the 4-point bending test was performed to evaluate the fatigue response of the modified and unmodified specimens by EN12697-24 standard. The fatigue tests were performed at 20oC and initial strain levels of 300, 500 and 700 microstrain using universal testing (UTM-14) apparatus. Based on the obtained results, the flexural stiffness of mixes containing both additives was lower than the reference mix. The reduction in the flexural stiffness continued as the Fiber and crumb PET content increased. The fatigue life of Fiber Reinforced mixes was higher than the reference one. At initial strain of 300 microstrain, the most increase in the fatigue life of Fiber Reinforced mixes containing 1 and 2 cm Fibers were equal to 149 and 177% of the reference mix, respectively. Also, at 700 microstrain the increases in the fatigue life of aforementioned mixes were 138 and 163% of the unmodified mix, respectively. The most increases in the fatigue life of the specimens containing 1 and 2% of the crumb PET were 148 and 163% of the reference one, respectively. Based on the obtained results and performed analyses, the optimum PET Fiber and crumb PET contents were 1 and 2% by weight of bitumen, respectively.

Background and Aim: The purpose of this study was to assess the fracture resistance of two different designs of tooth preparation and Fiber placement in Fiber-Reinforced composite restorations replacing a missing mandibular lateral incisor.Materials and Methods: Forty newly extracted human mandibular intact teeth (20 centrals and 20 canines) were selected for fabrication of twenty FRC inlay bridges. A box preparation design with straight Fibers and a slot design preparation with curved Fibers were implemented. After preparation, the teeth were mounted in self-cured acrylic resin with 6.5 mm distance from each other. PDL was simulated with polyether material. After taking impressions with polyether material, the impressions were poured with dental stone. The two groups of bridges were fabricated and bounded to teeth with panavia F2. The cyclic load of 1.2×106×20N×1.66HZ was applied with 130O angle. The samples were stored in 37oC water for seven days and then thermo cycled (2000 cyles, 5-55oC). The fracture strength was tested by a universal testing machine (Instron 1195) at a speed of 1 mm/min. The mode of fracture was observed under stereomicroscope. The data was analyzed by using independent sample T-test.Results: The mean fracture resistance for the box design and direct Fiber group was 1411.07 N and in the slot and curved Fibers group was 377.33 N. The group difference was statistically significant (P=0.012).Conclusion: It could be concluded that in Fiber-Reinforced composite restorations, box design with straight Fiber has more fracture resistance than slot design with curved Fiber.

This paper has been applied for designing of developed optimal Self-compacted Fiber Reinforced Concrete (SCFRC) incorporating polypropylene for construction of building industry. Concrete is a hybrid material incorporating of cementitious materials, water, aggregates and additive materials. These comprise the constituent materials of concrete. With the development of using materials in construction engineering, concrete blends have been the most widely utilized for building industry in all over the world. The elimination of vibration to compact concrete during placing through the use of self-compacting concrete leads to substantial advantages related to better homogeneity and hence, quality of the construction, improving of the workability, environmentally purposes and enhancement of the productivity by increasing the rate of construction. Over the last few years, the manifested developments of superplasticizers technology allowed great achievements in the conception of concrete Mixtures exhibiting selfcompacted performance. Since the last decades, some techniques have been presented to reach self-compacting requirements in fresh concrete mixes, on the basis of evaluation of the flowing characteristics of these Mixtures. The compressive strength is most applicate characteristic of concrete. However, there are many defects for concrete materials, including low anti cracking performance, bad toughness, low tensile strength. During the failure of the concrete structure under the action of load, the energy consumed is very limited, and many cracks with different size scale will come into being. The utilization of concrete Incorporating with Fibers is one of the proper issues of construction industry in last years. The main focus of this research to design a high performance self-compacted Fiber Reinforced concrete by using an evolutionary algorithm, which is implemented in MATLAB software (R 22019 a) version. Crow Search Algorithm (CSA) and Genetic Algorithm (GA) are statistical ways which are developed by optimization based meta-heuristic solutions. A total of 67 concrete Mixtures were considered by varying the levels of key factors affecting concrete strength of concrete, namely, water content (137. 2-195 kg/m3), cement content (325. 5-520 kg/m3), coarse aggregate content (722-920 kg/m3), fine aggregate content (804. 9-960 kg/m3), nano silica content (0-49. 6 kg/m3), percentage of volumetric of Fibers (0-0. 9 %), lime stone powder content (0-288. 9 kg/m3) and superplasticizer content (1. 75-10. 5 kg/m3) were developed to design optimized Mixture proportions. The objective function called maximizing concrete strength was formulated as an optimization problem on the basis of Multiple Linear Regression (MLR) method. The constrains including ratio of Mixture proportions and absolute volume of Mixture design were utilized to obtain an optimal-strength and cost-effective design. The concrete technological constraints were identified as the factors of experimental design for concrete production. The evolutionary implementation of results reached incorporating Mixture proportions having strengths in range of 30-88. 7 MPa. Five numerical examples for optimum Mixture design of SCFRC were considered to evaluate the capability and efficiency of CSA and GA algorithm. These results were compared and concluded that CSA (3. 38-14. 49 % of mean error) performed better than GA (7. 95-15. 52 % of mean error) for this application. Also, the proposed evolutionary CSA and GA algorithms are found to be reliable and robustness tools to solve and optimize engineering and concrete technological problem.

Despite substantial environmental and economic benefits, cold recycling of Asphalt pavements is not common due to some poor field performance reports. This study investigates the effect of Fiber reinforcement on the performance of cold recycled Mixtures. For this purpose, cold recycled Mixtures were Reinforced using polypropylene Fibers at two different lengths and three different contents. Indirect tensile strength, IDEAL-CT, and semicircular bending tests were carried out to find the optimum length and content of the Fiber. The effect of cement on the performance of Fiber-Reinforced Mixtures was also evaluated. The results show that although the use of polypropylene Fibers reduces the wet strength by up to 54%, it can increase the dry strength by up to 39%. The results also indicate a significant improvement in fracture indices obtained from IDEAL-CT and SCB tests in the presence of Fiber. The crack tolerance index was 3.5 times and the flexibility index was 2.8 times higher at the optimum Fiber content and length compared with the control Mixture. It was also concluded that the addition of cement to Fiber-Reinforced Mixture can eliminate the adverse effect of Fiber on moisture sensitivity while maintaining fracture properties similar to the control Mixture. The study results show that the combined use of Fibers and cement can lead to an economical cold recycled Mixture with reduced emulsified Asphalt content and improved mechanical properties.

Today, due to the rapid increase in the bitumen price and environmental problems, the hot mix recycling is taken into consideration in the construction of Asphalt pavements. From a technical point of view, Fibers are materials that improve a number of behaviors of Asphalt Mixtures. The aim of this research is to investigate the technical properties of reclaimed Asphalt pavement (RAP) in the presence of para-Fibers in order to achieve a suitable combination of these parameters. For this purpose, a new approach was utilized to design the experiment, analyze the results and choose the appropriate Asphalt Mixture. This approach uses a two-level factorial design in the Design Expert software environment based on desirability functions. The results showed that in the Mixture containing 50% RAP and 6% bitumen, increasing the Fibers from zero to 0.2% increases the Marshall strength value by 17.4% and decreases the Marshal flow value by 3.8%. In the same Mixture with 4% bitumen, with the increase of Fibers from zero to 0.2%, Marshall's strength and flow increase by 1.8 and 21.5, respectively. The most air voids are related to the Mixtures, containing 50% RAP, 4% bitumen and 0.2% Fibers. The results for selected materials showed that the suitable combination for the production of reclaimed Asphalt Mixtures according to the design criteria in Iran Highway Asphalt Paving Code is 6% bitumen, 50% RAP and 0.2% para-Fiber.

Fiber Reinforced concrete (FRC) has been used widely due to its advantages over plain concrete such as high energy absorption, post cracking behavior, flexural and impact strengths, arresting shrinkage crack.This research discusses the effect of increasing the percentage of polypropylene Fiber on flexural toughness and strength of FRC. Three percentages of polypropylene Fiber were substituted in 1% steel Fiber Reinforced concrete (SFRC). Finally, the mechanical properties of three types of hybrid Fiber Reinforced concretes were compared with each other and with steel Fiber Reinforced concrete by measuring their flexural toughness and flexural strength. A four-point bending test was adopted to determine the effect of hybrid Fibers on crack arresting and post crack behavior.The research results show that the more the percentage of polypropylene Fiber which is substituted in SFRC is, the less the amount of energy absorption and flexural toughness with FRC will be.

Effects of Polyphosphoric Acid (PPA) on the ultraviolet (UV) aging properties of Asphalt and Asphalt Mixture were studied. The morphologies of these binders were characterized by Fourier Transform Infrared Spectroscopy (FTIR) spectra and Thermo-Gravimetric (TG) analysis. Then, the e ects of PPA on Asphalt and its Mixture before and after UV aging were investigated in terms of the physical properties and pavement performances. Results showed that the mechanisms of PPA-modified Asphalt were physical and chemical reactions; both UV aging and PPA additive could prompt the polycondensation of light components in Asphalt. Compared to control samples, the introduction of PPA enhances the Asphalt properties and intensifies the Asphalt Mixture performance. Furthermore, the Asphalt performance aging variations (penetration aging index, softening point increment, ductility aging index, and G*/sin aging index) decreased signi cantly due to the introduction of PPA. It was shown that the effects of UV aging on the behaviors of Asphalt and Asphalt Mixture were constrained with the addition of PPA by inhibiting the increase of carbonyl in the oxidation process.