Flexural Strength Of Specimens Research Articles

Comparative assessment of flexural strength of monolithic zirconia with different thicknesses and two sintering techniques.

This study aimed to compare the flexural strength of monolithic zirconia with different thicknesses and two sintering techniques. This in vitro, experimental study was conducted on 28 monolithic zirconia discs with 10 mm diameter and 0.5 (n = 14) and 1.2 mm (n = 14) thickness. Each group was divided into two subgroups (n = 7) for fast (60 min) and conventional (120 min) sintering at 1450°C. After sintering, the specimens were thermocycled and their flexural strength was measured by piston-on-3-balls technique in a universal testing machine (0.5 mm/min, 1.2 mm pin diameter). Data were analyzed by the Weibull test, one-way analysis of variance, and Tukey's test (α = .05). The flexural strength of specimens with 1.2 mm thickness was significantly higher than that of specimens with 0.5 mm thickness (p < .05). The flexural strength of 1.2 mm/120-min group was slightly, but not significantly, higher than that of 1.2 mm/60-min group (p > .05). The flexural strength of 0.5 mm/120-min group was slightly, but not significantly, higher than that of 0.5 mm/60-min group (p > .05). The increase in thickness of monolithic zirconia increases its flexural strength; however, increasing the sintering time appears to have no significant effect on the flexural strength of monolithic zirconia.

Effect of high temperature on mechanical properties of lithium slag concrete

As the main gel material of concrete, cement is used in an astonishing amount every year in the construction industry. However, a large amount of CO2 is emitted into the atmosphere while producing cement. Therefore, it is the general trend to look for substitutes for cement and develop new green concrete. Lithium slag (LS) is the industrial waste discharged from lithium salt plants. Through testing, it is found that the chemical composition of LS has a high degree of coincidence with ordinary Portland cement (OPC) Therefore, LS can be incorporated into concrete as supplementary cementations material (SCM) to prepare lithium slag concrete (LSC). The pollution of the natural environment caused by a large number of piled-up and landfilled LS is immeasurable. Consuming and using LS in large quantities and with high efficiency not only eliminates the pollution of lithium slag to the natural environment, but also helps to reduce the amount of cement used in green concrete and truly reuse waste resources. In order to study the mechanical properties of post-heated LSC, the test were carried out for LSC specimens after high-temperature. The main influence factors were considered, including the temperatures of 20℃, 100 ℃, 300 ℃, 500 ℃ and 700 ℃, the contents of lithium slag in LSC of 0%, 10%, 20% and 30%, cooling method of LSC after exposure high temperature. The results showed that the mechanical properties of LS concrete specimens were slightly improved at 100 ℃, and when the temperature was 300 ℃ or higher, the damage to the specimens was huge and irreversible. An appropriate amount of LS (20% lithium slag content) could improve the strength of LSC. This paper also studied the relationship between lithium slag content and strengths of LS concrete. The research results show that adding an appropriate amount of LS to concrete improves the mechanical properties of concrete. When the LS replacement rate is 20%, the mass loss rate of LSC after different high temperature treatments was the minimum. The cubic compressive strength, axial compressive strength, and flexural strength of specimens with 20% LS substitution can be increased by 8.16%, 8.33%, and 13.46% after high temperature. The cubic compressive strength, axial compressive strength, and flexural strength of specimens with 20% LS substitution can be increased by 8.16%, 8.33%, and 13.46% after high temperature.

The Influence of Excitation Method on the Strength of Glass Powder High-Strength Cementitious Materials

Recycling economy and the re-utilization of solid waste have become important parts of sustainable development strategy. To improve the utilization rate of waste glass, glass powder high-strength cementitious material (GHSC) was prepared by replacing part of the cement in the cementitious material with ground waste glass powder. Firstly, the effect of glass powder particle size on the flexural and compressive strength of GHSC was investigated by the gray correlation method, and the optimal grinding time was obtained. Additionally, the effect of the magnitude of steam curing temperature and the length of steam curing time on the compressive strength and flexural strength of GHSC was investigated, and the mechanism of the effect of the curing regime on the strength was explored by examination of the microstructure. Finally, to simplify the curing process of GHSC, the effects of Ca(OH)2 and Na2SO4 as excitation agents on the compressive strength and flexural strength of GHSC at different dosing levels were compared. The results showed that glass powder with a particle size of less than 20 μm would improve the compressive strength and flexural strength of the specimen. Steam curing can significantly improve the flexural strength and compressive strength of GHSC specimens. At a steam curing temperature of 90 °C for a duration of three days, the compressive strength and flexural strength of GHSC increased by 76.7% and 98.2%, respectively, compared with the standard curing specimens. Ca(OH)2 and Na2SO4 as excitation agents significantly enhanced the compressive and flexural strengths of GHSC under standard curing conditions.

Valorization of glass waste as partial substitution of sand in concrete – Investigation of the physical and mechanical properties for a sustainable construction

Over the past few years, the valorization of industrial waste and by-products has become an essential issue due to the increasingly stringent regulations regarding the environmental protection and sustainable development. For the purpose of reducing our dependence on virgin raw materials, it was deemed interesting to consider the recycling and valorization of glass, which has high silica content, to develop new construction materials. Its use as a substitute raw material in the field of construction materials has attracted research attention, particularly the concrete industry adopts a number of methods to achieve this goal. In this context, a purely experimental study was conducted to investigate the physical and mechanical properties of fresh and hardened concrete at different curing times (3, 7 and 28 days) using different dosages of glass sand as a partial substitute for natural sand at 10%, 20%, and 30% and to determine the optimal composition of glass powder as a partial replacement for sand against the compressive strength of concrete. while maintaining a constant water-to-cement (W/C) ratio. An overall quantity of 9.5 kg of crushed waste glass was used with 264 kg of concrete mixes. The workability, density, slump, content air tests and strength properties were analyzed in terms of waste glass content in terms of waste glass content. This substitution results in concrete with favorable workability. Despite the absence of air-entraining agent, the concrete mixtures have air content between 2.3% and 1.9% and the density, is still comparable to the control mixes. The compressive strength of specimens with 20% waste glass content and the flexural strength of specimens with 10% waste glass content represented respectively 96% and 86% than of the control specimen at 28 days. The results proved a pozzolanic strength activity given by waste glass after 28 days for 10% and 20% of replacement of natural sand (0/1 mm). The results obtained indicate that glass can serve as a quality substitute for sand in concrete. These original achievements pave the way for more sustainable and environmentally friendly concrete mixes while addressing the inherent challenges of using glass waste in construction and infrastructure works

Performance evaluation and cost analysis of ternary blended geopolymers for sustainable built environment under different curing regimes

Geopolymer technology provides ecological and monetary benefits in supporting waste management. This study examines the influence of different aluminosilicate materials (85–100 % ground granulated blast furnace slag (GGBS), 0–15 % fly ash (FA), and 0–15 % waste glass powder (WGP)) and curing regimes (water and steam curing) on the mechanical and durability properties and production cost of geopolymers. The water-binder ratio, binder-fine aggregate, and alkaline activator-binder ratios were kept constant, whereas different amounts of superplasticizer were used in all the samples to achieve the target strength of 250 mm. The results revealed that the compressive and flexural strengths of specimens containing FA and WGP outperformed those of GGBS-based geopolymers. The compressive and flexural strength results demonstrated that the optimal FA and WGP replacement levels in ternary blended geopolymers were 10 % and 0–15 %, respectively; subsequent increases or decreases in FA and WGP replacement levels in most of the specimens resulted in mechanical properties similar to those of GGBS-based geopolymers without a significant increase in the production cost. Moreover, exposing specimens to freeze–thaw cycles led to higher compressive strength, ultrasonic velocity values, and weight irrespective of the curing regime, which can be credited to the continued geopolymerization reaction. Contrary to freeze–thaw cycles, only some specimens exhibited higher compressive and flexural strength once exposed to magnesium sulfate (MgSO4) solution. Like compressive and flexural strengths, the resistance of ternary blended geopolymers against freeze–thaw and sulfate attack is higher than that of GGBS-based geopolymers. It is also revealed that water- and steam-cured specimens provide better early- and later-age mechanical and durability properties; therefore, the choice of curing regime should be based on potential application. The positive results of this study indicate that ternary blended geopolymers have the potential to solve environmental challenges while also being futuristic and cost-effective in the production of eco-friendly and structural-grade materials.

Magnesium nanoparticle modified cement-based composites: Performance and compatibility in repair applications

Applying ordinary repair mortars onto the surface of degraded concrete elements has been a common approach in restoration operations. Since the properties of cement-based composites depend on nano-structural features, proper addition of nanoparticles can enhance performance. In the present study, the physico-mechanical performance of concrete and mortar mixtures incorporating magnesium nanoparticles was investigated. The workability and flowability of the mixtures, along with compressive, tensile, and flexural strengths of specimens were evaluated. A total of 284 cylindrical, cubic, and prismatic beam specimens having different dosages of magnesium nanoparticles as partial replacement for cement were assessed to quantify the effects of adding magnesium nanoparticles. Furthermore, analysis of the compatibility between the repair mortar and the existing concrete substrate was examined using four-point bending tests on repaired beam elements to characterize the different modes of failure. Two approaches of substrate surface preparation featuring smooth and rough interfaces were adopted, and the effect of interface texture on the mechanical properties of the repaired beam specimens was evaluated. The results show that specimens incorporating magnesium nanoparticles achieved 37%, 37%, and 63% higher compressive, tensile, and flexural strengths, respectively, compared with that of the reference specimens. Moreover, the set of concrete beams with rough interface showed compatible failure modes, while those with smooth contact interface had incompatible modes of failure.

Microencapsulated phase change material incorporated light transmitting gypsum composite for thermal energy saving in buildings

The increased energy consumption for specific applications, including heating, cooling, air conditioning and lighting of residential and commercial buildings accelerate the research efforts concentrated on developing thermal energy storage capacity of buildings materials in recent years. Likewise, the development of light-transmitting building elements is a novel energy-saving technique that enhances lighting efficiency in buildings. In light of these, the current study seeks to design an untried microencapsulated phase change material (MPCM) integrated glass fiber reinforced gypsum composite with sufficient light-transmitting properties and thermal energy storage capacity. In this research, a multi-scale investigation of light-transmitting gypsum composite was conducted experimentally with physical, mechanical, chemical, microstructural, thermal, light transmittance and solar thermoregulation tests. The gypsum composite is formed from α-gypsum, water, polymer admixture, alkali-resistant glass fiber (AR-GF), several concentrations of MPCM, and plastic optical grids to allow light to transmit through the board. Although higher fractions of MPCM yielded an apparent decrease in mechanical strength test results, 5 wt% introduction of MPCM to the reference matrix reduced the compressive and flexural strength of specimens by 1 and 8 %, respectively. The results verified a reduction trend in thermal conductivity of composites with MPCM loading. DSC investigations revealed that the melting temperature and the regarding latent heat storage capacity of gypsum composite with 15 wt% of MCPM are 17.76 °C and 19.2 J/g, respectively. Light-transmitting gypsum composites showed up to ~10 % light transmittance, that can greatly increase the efficiency of lighting in buildings. The produced gypsum composites with MPCM kept the test room cooler during the highest temperature, while it provided a warmer room during the nighttime for an extended time. The study's findings are applicable to increase thermal comfort by reducing the significant temperature variations in buildings and improving artificial lighting efficiency, encouraging the design of sustainable building applications.

Mechanical Properties of Biocomposite with Various Composition of CaCO3 and Starch

Calcium carbonate has the potential to be used in the development of medical materials, including biomaterials. Biocomposite is composed of CaCO3 as matrix material and bioplastic from the combination of corn starch and cassava starch as reinforcement. This study aims to determine mechanical properties such as tensile strength and bending/flexural strength with varying compositions of CaCO3 and bioplastic. Characterization of the biocomposite uses Scanning Electron Microscope to observe the microstructure and composition elements of their structure. This study used 4 variations in the ratio of CaCO3 suspension: (Corn Starch + Cassava Starch). Each sample was characterized using specimen code A for composition 30:70 (w/w) percent and specimen B for composition 40:60 (w/w) percent, specimen C for composition 50:50 (w/w) percent, and specimen D for composition 60:40 (w/w) percent. Based on the results of shrinkage measurements on flexural strength specimens, specimen B has the lowest percentage value of 15±0.01 percent. The lowest tensile strength specimen is found in specimens C and D at 12±0.01 percent. The tensile test results also showed that specimen D had a higher ultimate strength value than the other specimens, which was 0.06±0.03 MPa. Microstructure characterization was carried out using scanning electron microscopy with energy-dispersive X-ray spectroscopy, which revealed the presence of Oxygen at approximately 48.39 percent mass, Carbon at approximately 30.27 percent mass, Nitrogen at approximately 11.77 percent mass, Calcium at approximately 9.57 percent mass, with Calcium being detected in the form of Calcium Carbonate (CaCO3).

Study on mechanical properties and microstructure of aluminate cement-based materials incorporating recycled brick powder after exposure to elevated temperatures

The mechanical properties of aluminate cement-based materials (A-CM) that partially replaced by recycled brick powder (RBP) after exposure to elevated temperatures were studied in this paper. A total of 72 prism specimens were prepared, and the main parameters included RBP replacement ratio (0%, 5%, 10%, and 15%) and exposure temperature (20 °C, 200 °C, 400 °C, 600 °C, 800 °C, and 1000 °C). The compressive and flexural tests of specimens after exposure to elevated temperatures were conducted, and the phase of hydration products and the microstructure of hardened cement paste were systematically analyzed by microscopic tests. The influence mechanism of RBP on the mechanical properties of A-CM before and after high temperatures was revealed. Results showed that the A-CM specimen with RBP replacement ratio of 5% presented the highest compressive and flexural strength at any exposure temperature. The compressive strength of specimens with the same RBP replacement ratio first increased and then decreased with the increase of exposure temperatures, and the highest compressive strength was obtained after exposure to 200 °C. While the flexural strength of specimens at any RBP replacement ratio decreased all the time with the increase of exposure temperature. Moreover, the explosive spalling of A-CM specimens after exposure to 1000 °C could be inhibited when the RBP replacement ratio exceeded 10%. Finally, a calculation method that considered the effect of RBP replacement ratio to predict the compressive and flexural strength of A-CM specimens after exposure to elevated temperatures was proposed and validated.

Mechanical and surface properties of a 3D-printed dental resin reinforced with graphene

Objectives: Commercial photocurable polymers used in dental additive manufacturing still have mechanical limitations. The incorporation of graphene may provide interesting advantages in this field. This study aimed to evaluate in vitro the effect of adding graphene nanoparticles to a 3D-printed polymethylmethacrylate dental resin in terms of surface roughness, flexural properties, and hardness. Methods: A 3D-printed dental resin (Dental Sand, Harz Lab) was loaded with four different graphene nanoplatelet (Graphenest) concentrations: 0.01wt%, 0.1wt%, 0.25wt%, and 0.5wt%. The neat resin was used as the control group. The surface roughness was measured with a contact profilometer using bar-shaped specimens (50x10x4mm). The flexural strength of specimens (80x10x4mm) from each group was calculated using the 3-point bending test in a Universal Test Machine. Hardness shore D was measured using a manual durometer on round-shaped specimens (12x6mm). Data were evaluated using the Kruskall-Wallis test followed by post-hoc Bonferroni corrected pairwise inter-group comparisons. Statistical significance was set at p&lt;0.05. Results: Graphene improved 3D-printed PMMA resin hardness with statistical significance at a concentration of 0.01wt% (p=0.043). Surface roughness increased with graphene concentrations above 0.01wt%, with statistically significant differences at 0.25wt% (p=0.006) and 0.5wt% (p=0.005) concentrations. Flexural properties worsened with increased graphene concentrations, and these differences were significant in the concentrations of 0.25wt% (p=0.028) and 0.5wt% (p=0.006). Conclusions: The use of graphene as a mechanical reinforcement nanomaterial seems to be viable at low concentrations without prejudice to the surface roughness of a 3D-printed polymethylmethacrylate resin.

Influence of Cotton Knitted Fabric Waste Addition on Concrete Properties

Manufacturing cotton knitted fabric apparel generates a substantial amount of production (pre-consumer) waste. One of the ways to alleviate the environmental impact of this is to use the cotton knitted fabric production waste (CKFW) in concrete, which had the simultaneous benefit of reducing the use of virgin aggregate. The aim of this research was to examine the influence of CKFW on concrete properties, and to explore the possible application of this novel material in the construction industry for the production of precast building elements based on its characteristics. An additional goal was to enhance certain properties of concrete and determine the shortcomings of CKFW concrete. A total of 10 mixes were made and tested. CKFW was used at rates of 1.7% and 3.5% of the total mix volume. All mixtures had the same amount of cement, with three mixes having the addition of silica fume. Crushed limestone was used as the aggregate with different aggregate size combinations. Two types of polycarboxylic ether-based superplasticizer were used. The properties of the fresh mix were determined by the slump method. The ultrasonic pulse velocity, dynamic modulus of elasticity, flexural strength and compressive strength were tested on 28-day-old concrete specimens. The σ–δ diagram is also presented in this paper. We learned that the flexural strength of specimens with CKFW addition was increased by up to 38% but the compressive strength was reduced by up to 20% compared to the reference concrete mix. The CKFW mixtures had higher ductility and permeability. Additionally, silica fume had a positive effect on the concretes with a higher percentage of textiles. The percentages of textile waste used in this study affected the density of concrete in a range of 0–2%. Based on the obtained results, we offer recommendations for further tests and possible applications.

Effect of Casting Position on Mechanical Performance of Ultra-High Performance Concrete.

The mechanical performance of ultra-high performance concrete (UHPC) is a function of fiber distribution and orientation, which are affected by the processing of the fresh material. In this study, the influences of two casting positions (mid-cast and end-cast) on strength and fracture properties of UHPCs with different fiber types and fiber contents were investigated. The results show that mid-cast specimens have higher flexural strength and fracture properties than end-cast specimens, while the compressive strength is almost unaffected by casting position. Compared to specimens with straight fibers, the flexural strength of specimens with hooked-end fibers is more likely to be affected by casting position. The residual load-to-peak load ratio is independent of casting position but affected by fiber type and fiber content.

Impact of high-speed sintering and choice of preshaded monochrome or multilayered blanks on fatigue behavior of 4 mol% yttria-stabilized tetragonal zirconia polycrystal

Statement of problemHigh-speed sintering allows the rapid fabrication of esthetic restorations with adequate flexural strength. However, data on the fatigue behavior of high-speed sintered 4 mol% yttria-stabilized tetragonal zirconia polycrystal (4Y-TZP) are lacking. PurposeThe purpose of this in vitro study was to examine the effect of high-speed sintering and the preshading of blanks (monochrome versus multilayer) on the fatigue behavior of 4Y-TZP ceramics. Material and methodsFour-point flexural strength specimens (N=405) were fabricated from high-speed sintered multilayer 4Y-TZP (Zolid DRS) processed at 1580 °C for about 20 minutes and conventionally sintered at 1450 °C for about 10 hours, multilayer 4Y-TZP (Zolid Gen-x), and monochrome 4Y-TZP (Ceramill Zolid HT+PS), the control group. The specimens were loaded under 5 different dynamic test conditions for fatigue testing (P1-P5). Three were step-stress protocols (P1: 50 N for 5000 cycles; P2: 10 N for 1000 cycles, P3: 5% for 5000 cycles), 1 was tested with a constant force of 720 N (P4), and 1 was tested for different constant load levels (P5). For analysis of P1-P3, the Kaplan-Meier test and Mantel Cox test were performed (α=.05). P4 was analyzed with the Kolmogorov-Smirnov, Kruskal-Wallis, and Mann-Whitney U tests, and P5 by creating a load-cycle diagram. A fracture analysis was performed. ResultsZMLC showed better fatigue behavior than ZMLH (P≤.006) and ZMOC (P≤.002) in all 3 step-stress protocols (P1-P3). ZMLH showed results comparable with those for ZMOC (P≥.285). In P4 and P5, all materials showed comparable values (P=.163 for P4). ConclusionsThe multilayer technique showed a positive effect on the fatigue behavior of 4Y-TZP. In contrast, high-speed sintering negatively influenced the fatigue behavior of multilayer 4Y-TZP. The high-speed sintered material showed no deterioration compared with the conventional sintered monochrome material.

Effects of water-cement ratio and superplasticizer dosage on mechanical and microstructure formation of styrene-butyl acrylate copolymer concrete

The interaction between nanoparticles of Styrene-Butyl Acrylate latex and cement particles with various water-cement and superplasticizers-cement ratios during the hydration process has been investigated to achieve the best chemical combination of the materials for enhancing the mechanical properties and workability of the concrete. Analyses and experimental results have shown that the adhesive properties of Styrene Butyl Acrylate (SBA) copolymer latex along with an appropriate percentage of superplasticizers promote the performances of interlayer bonding of concrete. The compressive, splitting, and flexural strengths of specimens have been studied and the formations of the microstructures by the implementation of FESEM, EDX, XRD, FTIR, TEM, and DLS, have been analyzed. The obtained results show the considerable enhancement in the structural behavior of the copolymer-modified concrete in comparison with the control samples by creating cohesive microstructures in the presence of the copolymer. Appropriate water-cement ratio and superplasticizers were selected to study the efficient distribution of the copolymer nanoparticles throughout the cement matrix by the implementation of the FESEM and EDX analyses. The constructed polymer bridges and films between layers of Ca(OH)2 crystals have yielded to the formation of an internal cohesive strong microstructure. Also, XRD and FTIR results indicate that the stability and formation of ettringite have been enhanced by the development of calcium aluminate reaction with SBA copolymer. In the cement pore solution, the chemical interaction between nanoparticles, and Ca2+, the copolymer nanoparticles adsorption on cement paste were applied and the enhanced microstructure of the concrete was obtained.

Effect of Modified Carbon Nanotubes Epoxy on the Mechanical Properties of Concrete Reinforced with FRP Sheets

Today, using Fiber Reinforced Polymer (FRP) sheets is one of the conventional methods in retrofitting concrete structures. Some factors affecting FRP sheets proper performance include mechanical properties, surface specifications, connector’s material and connecting approach in concrete elements. Previous studies showed that FRP epoxy resin and its basic surface have a significant impact on the ultimate bearing capacity. In line with the development of nanotechnology in recent years, this paper presents an experimental study to show the effects of adding the best percentage of nano-carbons to adhesive resin and evaluate the ultimate axial, shear and bending strengths in concrete samples. The results show that using FRP with carbon nanotube reinforced resins will significantly increase stiffness and ductility by 100%; moreover, it shows an effective increase of almost 13% in axial and flexural strengths of specimens.

Influence of Boric Acid Additive on Physical Properties of Utilizing Wastes for Producing Eco-Friendly Fired Clay Tiles

This paper aimed at studying the influence of additive material boric acid in eco-friendly fired clay tiles. It is used as additive material by mixing with rice husk ash (RHA), brown glass cullet (BGC), local clay (LC), and sediment soil (SS). Effects of boric acid on the physical properties of ceramic bodies were investigated. The texture of specimen by utilizing waste materials was also studied. Mixture formulations consisted of 60% BGC, 10% RHA, 0-30% LC, and 0-30% SS with varying boric acid addition of 0-2%. Specimens were formed by uniaxial pressing with 100 bars, fired at 850 and 900°C, heating rate 100°C/h, and soaked for 1 h. The results showed that adding boric acid up to 2% had increased the flexural strength and decreased the water absorption of these specimens when fired at 850°C. On the contrary, the effects of adding boric acid fired at 900°C had decreased flexural strength and increased water absorption that showed the phenomenon of expanding specimens. However, the optimal formula of these clay tiles both fired at 850 and 900°C have passed the Thai Industrial Standards (TIS 2508-2555); Type BIII. Scanning electron microscope should they that microstructure characterization was in the glassy crystalline phase was found in high flexural strength specimens. In summary, exploiting boric acid can improve the physical properties of specimens with a low firing temperature, and fired clay wall tiles can be developed in this study. They can be identified as an environmentally eco-friendly building product.

The effect of graphene oxide on the mechanical properties, impermeability and corrosion resistance of cement mortar containing mineral admixtures

Graphene oxide (GO) is one of the nanomaterials that have attracted the most attention of researchers in recent years. Because of its excellent mechanical, thermal and electrical properties, it is widely used in the fields of energy, photoelectric, catalysis and materials, and it has shown broad development prospects. For the high demand of cement-based materials in buildings, as a new cement composites reinforcement agent, GO has been widely studied by researchers. Based on previous studies, cement, silica fume (SF) and fly ash (FA) were used as composite cementitious materials in this experiment, and the effects of different GO contents (0.00%, 0.01%, 0.03%, 0.05%, 0.07%) on the mechanical properties of mortar were analyzed. In addition, the impermeability and sulfate resistance of the modified mortar were studied. The results showed that under the same curing conditions and ages, when the GO content is 0.05%, the flexural strength of the specimens after 28 days of curing is the highest, reaching 10.8 MPa, and the improvement rate is 16.1%. When the GO content is 0.03%, the compressive strength of the specimens after 28 days of curing is the highest, reaching 64.5 MPa, and the improvement rate is 12.4%. In addition, when the dosage of GO is 0.03%, the durability of the mortar is also extremely improved. The impermeability of the mortar is 80% higher than the reference specimens. The strength retention rate under the action of sulfate corrosion is also the highest, which is 11.3% and 6.7% higher than the compressive strength and flexural strength of the reference specimens that corroded for 3 months. GO was proved to be an excellent reinforcement agent for cement-based materials. Through SEM and XRD analysis, it was found that GO promoted the hydration reaction, and it played a filling effect and template role in the mortar matrix. Its two-dimensional lamella structure regulates the morphology of hydration products and enhances the interface adhesion between the matrix and the aggregate. In addition, its nano-filling effect eliminates a large number of micro-pores in the mortar and increases the density of the matrix.

EFFECT OF POLYPROPYLENE FIBER ON PROPERTIES OF GEOPOLYMER CONCRETE BASED METAKOLIN

Climate changes and global warming are an international issue around the world and caused by the accumulation of greenhouse gases, and one of these reasons Portland cement industry which releases high amounts of CO2, which causes 65% of the global warming effect. So the essential component for sustainable development in the construction industry is the improvement of alternatives for cement. One of the promising materials in the field of concrete industry is the geopolymer concrete, which attracted spotlight over the past decade with its comparable performance with Portland cement. This paper presents a systematic review of different research works done in the region of geopolymer concrete based metakoalin reinforced with polypropylene fiber and under ambient temperature. The mechanical behavior was enhanced significantly through experimental results. The compressive strength was improved 14.75% with 1% of polypropylene fiber while the increment of splitting tensile strength was 12.3 %, 15.76 % respectively. The flexural strength of specimens was also improved when compared with the non-fiber geopolymer concrete. The highest increment obtained with 1.5% of fiber volume content was 27.3%. Modulus of elasticity was also improved with increment to 13.1%, when compared with the non-fiber geopolymer concrete, also from experiment adding of fibers lead to a decrease in the density of GPC. The compressive performance and flexural performance of fiber-reinforced geopolymer concrete were also better than specimens without fiber.

Utilization of Waste Glass and Fly Ash as a Replacement of Material Concrete

Waste glass creates serious environmental problems, mainly due to the inconsistency of waste glass streams. Increasing environmental pressure to reduce solid waste and to recycle as much as possible. The properties of concretes containing waste glass as fine aggregate were investigated in this study. The purpose of this research was to determine the influence and percentage optimum of glass waste as replacement of fine aggregate and fly ash as replacement of 20% of weight cement in flexural strength and sorptivity of concrete. This study used the experimental method to measure the results of treatment in research samples in the laboratory. The samples used 24 pieces blocks with dimensions of 150 mm x 150 mm with a length of 600 mm as flexural strength specimens and 24 pieces cylinders with a diameter of 100 mm with height of 50 mm as sorptivity specimens. The variation of glass powder starts from normal concrete 0%, 10%, 20%, 30% and 40%, each variation consists of 4 samples. The conclusions of this study are there is significant effect between glass powder variations as a replacement for part of fine aggregate and fly ash as a replacement for 20% of the weight of cement to the flexural strength and sorptivity of concrete. The optimum percentage 18.5% of glass powder with a flexural strength of 2.971 MPa and the percentage of the use of glass waste as a partial replacement for optimal fine aggregate which is in the variation of 20% glass powder with an initial sorptivity minimum value of 0.0076 mm/s1/2 and in the variation of 40% glass powder with a secondary sorptivity minimum value of 0.0034 mm/s1/2.

Flexural strength of polymethyl methacrylate reinforced with high-performance polymer and metal mesh

Background: The flexural strength (FS) of a denture base material is of great concern, and many approaches have been used to strengthen the denture acrylic resins. The present study aimed to evaluate the effect of high-performance polymer (BioHPP) and metal mesh reinforcement on the FS of a heat-cured poly methyl methacrylate (PMMA) acrylic resin. Materials and Methods: This experimental study was done on 30 rectangular specimens (64 mm × 13 mm × 3 mm) of a heat-cured PMMA resin. The specimens were divided into three groups (n = 10) to be reinforced with either metal mesh or BioHPP mesh; one group was left nonreinforced, serving as the control group. The FS of specimens was assessed through a 3-point bending test by using a universal testing machine at a crosshead speed of 2 mm/min. Kruskal–Wallis H and Dunn's post hoc tests were used to compare the FS among the groups (alpha = 0.05). Results: The FS in the metal-reinforced group was statistically significantly higher than the two other groups (P &lt; 0.001). However, the FS of the BioHPP-reinforced samples was not statistically significantly higher than the nonreinforced ones (P = 0.614). Conclusion: Reinforcing the PMMA with metal mesh significantly enhances its FS while BioHPP has no significant effect on the PMMA FS.