Optimum Compressive Strength Research Articles

Reuse of Waste Plastics in Developing Countries: Properties of Waste Plastic-Sand Composites

Waste plastics are a major problem in developing countries, where efficient collection and recycling systems often do not exist. Plastic bonded sand composites provide a low-cost recycling alternative for selected waste plastics. This research has investigated the production and properties of plastic bonded sand manufactured using low-density and high-density polyethylene (LDPE and HDPE). Plastic bonded sand production in The Gambia was used as a case study to identify potential barriers to the technology. Processing was done by oven moulding, or a heat-mixing technique, and the properties of the LDPE and HDPE bonded sand samples formed have been determined. Processing at temperatures between 250 °C and 325 °C produced optimum compressive and flexural strengths. Higher processing temperatures reduced strength and lower temperatures produced inhomogeneous samples. Thermal plastic degradation occurs at 400 °C in N2 and 250 °C in air. Processing at temperatures below 250 °C in anoxic conditions is necessary to control off-gases. The optimum sand addition to produce the highest compressive strength was between 65 and 80%, depending on the sand particle size. HDPE produced higher maximum compressive strengths (37.1 MPa) compared to LDPE (27.2 MPa). Plastic bonded sand has increased strength, toughness, ductility, and thermal conductivity compared to C20/25 concrete and sandcrete and it can be used for wall construction blocks and paving tiles. The potential applications and implications of processing waste plastics in developing countries into plastic bonded sand are discussed.Graphical

Influence of Modified Chemical Compositions on Palm Oil Fuel Ash to the Physico-Mechanical Properties of Porcelain

Palm oil fuel ash (POFA) is produced and disposed of by the palm oil industries as waste after burning palm fiber, husk, kernel, and shell as fuel to general electricity in-house. The aim of this research is to investigate the influence of modified chemical compositions on POFA on the physico-mechanical properties of porcelain. POFA was washed with 1, 2, and 3 Molar of HCl acid and heat treated. The powder was partially replaced with quartz at 15 wt.% and mixed in a ball mill machine for 12 hours. Modified POFA (admixture of CaO, Al2O3, MgO, P2O5, SiO2, and Fe2O3) was added to the porcelain composition at 1, 2, 3, 4, 5, 10, and 15 wt.% to measure its influence on physico-mechanical properties of porcelain. The mixture was homogeneously mixed and dry pressed into a pellet at mould pressure 91 MPa and sintered at 1150 °C for 2 hours soaking time. The result of this research shows that these chemical compounds influenced physico-mechanical properties of porcelain, the optimum bulk density, compressive strength, and Vickers micro hardness values were obtained by the addition of modified POFA (admixture of CaO, Al2O3, MgO, P2O5, SiO2, and Fe2O3).

Study of Different Composition of Gypsum as Retarder in Ordinary Portland Cement

Mortar is another construction medium made of cement, which is mixed with sands and water, and lime is applied to increase the product's longevity. The gypsum renders workability to make mortar or concrete by keeping the cement in plastic state at early age of hydration. The gypsum is called the retarding agent of cement because the gypsum which is mainly used for regulating the setting time of cement. To get the optimal setting time for optimum compressive strength, gypsum in the cement needs to be control. Cement setting time when it hydrates and renders cement paste when combined with water. The objective of this research is to analyze the effect of different amount in Ordinary Portland Cement (OPC). Vicat apparatus was used to analyze the initial setting time of cement paste. Gypsum and clinker were used in production of mortar with the size 50 mm x 50 mm x 50 mm. This research deals with observation of the cement setting time to point out some differences that would effect to strength of mortar. The results reveal that control gypsum with 4% of gypsum has the highest strength as compared to 0% of gypsum and 8% of gypsum. The setting time of cement paste are discussed with respect to their influence on the strength of mortar.

Understanding the binder chemistry, microstructure, and physical properties of volcanic ash phosphate geopolymer binder

AbstractThis work aims to assess the influence of the chemical composition of the binder resulting from the reaction of phosphoric acid and volcanic ash on its final characteristics. Six initial compositions of volcanic ash phosphate geopolymer with molar ratios Fe/P of 0.27, 0.5, 0.54, 0.81, 1, and 1.5 were designed by adding various dosages of phosphoric acid to volcanic ash. The results show that the hardening time increases with the decrease of molar ratios Fe/P. An excess of phosphoric acid leads to an unstable binder that is partially destroyed with the aging of the binder. The volcanic ash phosphate geopolymer with molar ratios of Fe/P = 0.5–0.54 has the optimum compressive strength (49–53 MPa at 90 days), the lowest water absorption (8.8‐9.5 wt.%) as well as porosity (18–19.6 vol.%). The main binder is a porous phase of ferro‐silico‐aluminophosphate. Secondary phases were also identified in some mixes including ferro‐aluminophosphate and magnesium phosphate.

An Empirical Model for Geopolymer Reactions Involving Fly Ash and GGBS

Numerous works are reported in literature regarding the enhancement of compressive strength of fly ash-GGBS geopolymer combinations with addition of alkali activators of varying concentrations. However, a limited study has been chronicled, revealing the specific role of alkali or alkaline earth contributed by the fly ash-GGBS combinations on the compressive strength development. It is well known that the strength of a geopolymer is dependent on gel formation from Al/Si ratio, Ca/Si ratio, and Ca/(Si + Al) ratio but their exact role when cured for various extended periods is unknown as yet. In the present study, alkali concentration in a fly ash-GGBS geopolymer combination was varied from 6 M to 12 M with increments of two mol in six different fly ash-GGBS combinations with a minimum of 20 percent and a maximum of 70 percent GGBS. The correlation coefficients between compressive strength and Al/Si, Ca/Si, and Ca/(Si + Al) ratios exhibited values higher than 0.95 taken individually. Multiple linear regression analysis with compressive strength (as dependent parameter) and individual values of Al/Si, Ca/Si, and Ca/(Si + Al) ratios (as independent parameters) was effectuated. It was observed that, depending on the composition, the compressive strength circumstantiated a changeover from Ca/Si to Ca/(Si + Al) ratio in the intermediate composition range. Such a detailed analysis is considered supportive of developing a suitable composition which will provide the optimum compressive strength of the combination.

Comparison Between Scheffe’s Second Degree (5,2) And Third Degree (5,3) Polynomial Models In The Optimization Of Compressive Strength Of Glass Fibre Reinforced Concrete (GFRC)

Purpose: This research work aimed at formulating an optimization model based on Scheffe’s Third Degree Polynomial (5,3) that can be used to optimize the compressive strength of Glass Fibre Reinforced Concrete (GFRC), which is then compared to Scheffe’s Second Degree Polynomial (5,2) formulation developed by Nwachukwu and others (2017) .
 Methodology: Using Scheffe’s Simplex method, the compressive strength of GFRC was determined for different ratios. Control experiments were also carried out and the compressive strength determined. After the tests have been conducted, the adequacy of the model was tested using fisher’s f-test and the result of the test shows a good correlation between the model and control results. 
 Findings: Optimum compressive strength for the Scheffe’s (5,3) model was obtained as 21.82 N/mm2. This is slightly higher than the optimum compressive strength for Scheffe’s (5,2) model which was obtained as 20.71 N/mm2 by Nwachukwu and others (2017). Since structural concrete elements are generally made with concrete having a compressive strength of 20 to 35 MPa (or 20 to35 N/mm2 ), it then means that optimized GFRC based on both Scheffe’s models can produce the required compressive strength needed in major construction projects such as bridges and light-weight structures.
 Recommendations: Major stakeholders in the construction industry are therefore advised to use optimized GFRC as it is far cheaper and still possess the required strength needed for construction works.

Investigation on Mechanical and Durability Properties of Concrete Mixed with Silica Fume as Cementitious Material and Coal Bottom Ash as Fine Aggregate Replacement Material

Cement production produces a high amount of carbon dioxide, which has a negative impact on the environment. By utilizing waste products instead of cement, environmental degradation can be reduced. The current study was undertaken to study the mechanical and durability performance of concrete by replacing 7.5%, 10%, and 12.5% silica fume (SF) of cement weight. Additionally, coal bottom ash (CBA) was also substituted as fine aggregates with 10%, 20%, and 30%. Compressive strength and indirect tensile strength were the major parameters regarding mechanical properties, while corrosion analysis and sulfate attack were set for durability performance. Sixteen mixes were prepared including a control mix. Out of these, three mixes contained SF, three mixes contained CBA, and eight mixes contained both SF and CBA with 1:2:4 ratio at 0.5 w/b ratio. The results concluded that the addition of 12.5% SF and 30% CBA gives optimum compressive strength and tensile strength. Furthermore, using the SF and CBA reduces the workability of concrete. Furthermore, the use of these byproducts increased the durability in terms of corrosion and sulfate attack.

Interfacial characteristics and wear performances of iron matrix composites reinforced with zirconia-toughened alumina ceramic particles

Zirconia-toughened alumina ceramic particle (ZTAP)-reinforced high Cr cast Fe matrix composites (ZTAP/Fe composites) are promising advanced wear-resistant materials. However, due to wear and tear, the ceramic particles may shed from the Fe matrix because of their low interfacial bonding properties. In the present work, we investigated interfacial characteristics and abrasive wear behaviours of ZTAP/Fe composites. Results showed that sintering played a significant role in the formation of sintering necks and consequently affected both compressive strengths and porosities of ZTA ceramic preforms. Optimum compressive strength (44.3 MPa) and porosity (25.2%) were obtained when sintering was performed at 1350 °C for 1 h. Subsequently, ZTAP/Fe composites without evident defects were fabricated by infiltration casting. Scanning electron microscopy, electron probe microanalysis and transmission electron microscopy were also used to analyse the microstructures and phase constituents of the interfacial layers of composites. Effects of applied wear loads on the wear behaviour evolutions and wear mechanisms of composites were examined. Wear resistances of ZTAP/Fe composites were found to be 1.64–2.21 times as compared to the Cr15 specimen.

Application of sugarcane ash as an additional cementitious material in concrete

The use of agricultural materials has increased in demand as of years progress in both rural and urban industrial zones. Hence, the disposal of agricultural waste of fibre materials increased in environment. The concrete structures made from cementitious materials often defected from settlements and static loads. Furthermore, the sugarcane fibres commonly tossed as wastes led to pollution in the environment. In this research, sugarcane was processed and burned at 500 °C into sugarcane ash (SCA) and implemented in the mix proportion of lightweight concrete and concrete mortars. Lightweight concrete specimens with dimensions 100x100x100-mm were casted according to dosage of SCA at 0%, 5%, 10%, and 15% while a specimen consisting of SCA and lightweight expanded clay aggregate (LECA) at dosage of 15% and 40% respectively. The fineness and consistency tests were performed experimentally through the Blaine air permeability and Vicat apparatus. Moreover, the cube compression test for specimens were performed on a Universal Testing Machine (UTM). The appropriate fineness and consistency results were achieved by specimens with 15% SCA and controlled mortar that at 183.31 m2/kg and 0.35 water-cement ratio, respectively. Additionally, the optimum compressive strength was obtained for specimen with 5% SCA at 32.78 MPa. Overall, both the mechanical and physical properties of the concrete were fully enhanced.

Performance of concrete made from cupola furnace slag and recycled concrete aggregate

Portland cement concrete (PCC) is an unquestionably flexible and valuable material for any nation's infrastructure and construction development. Nevertheless, the negative health impacts of cement production, the aggregate fraction of concrete, and the building supply shortage are some drawbacks of concrete use. Cupola slag (CS) and recycled coarse concrete (RCA) wastes from industrial processes, construction, and demolition sites are disposed of into the environment, resulting in pollution that threatens marine, agriculture, and public health. Therefore, CS and RCA as a binder and coarse aggregate in concrete production would help protect the environment. This study presents the outcome of an experimental investigation on (i) partial substitution of cement at percentage levels of 0% to 25% in steps of 5% with granulated cupola slag, (GCF); (ii) partially substitution of coarse granite from 0% to 50% in steps of 10%; with coarse cupola slag (CCS); and (iii) complete replacement of CG with recycled coarse aggregates and subsequently partially replaced with CCS from 0% to 50% in steps of 10%. The fresh and hardened properties of concrete, such as workability and compressive strength, were tested. The test results generally showed that the workability increases with an increase in percentage replacement. However, at 7, 14, 28, and 56 days concrete produced from the partial replacement of cement with GCF had the optimum compressive strength of 9.65 N/mm2, 15.85 N/mm2, 20.37 N/mm2, and 22.15 N/mm2 at 10% replacement. The strength, however, increased by 13.67%, 23.54%, 29.42%, and 25.42% compared to the control sample. Similarly, concrete produced from the partial replacement of CG with CCS gave the optimum compressive strength at 10% replacement with a value of 14.89 N/mm2 at 28 days. The compressive strength obtained from the complete replacement of CG with RCA was lower compared with the control samples at 7, 14, 28, and 56 days. It can be concluded that the concrete made with CS and RCA show a satisfactory development and consistency in strength as compared to control sample.

Influence of Waste Tire Particles on Freeze–Thaw Resistance and Impermeability Performance of Waste Tires/Sand-Based Autoclaved Aerated Concrete Composites

Waste tires/sand-based autoclaved aerated concrete (SAAC) composites were prepared by mixing waste tires, which have different particle sizes and content. The physical performance, mechanical properties, freeze–thaw resistance, impermeability performance, phase composition, and microstructure of waste tires/sand-based autoclaved aerated concrete composite materials were examined. The results demonstrated that the 750-μm-sized waste tire particles on the surface of the SAAC composite did not agglomerate. Moreover, these particles did not damage the pore structure of the composites. The SAAC composites, with a relatively high compressive strength and low mass-loss rate, were obtained when the contents of waste tire particles ranged from 1.0 to 2.5 wt.%. For composites prepared with 2.0 wt.% of 750-μm-sized waste tire particles, the optimal compressive and flexural strength values were 3.20 and 0.95 MPa, respectively. The increase in the rate of water absorption on SAAC composites was lowest (i.e., 16.3%) when the soaking time was from 24 to 120 h.

Strength properties of renewable bio-based lightweight foam concrete incorporating of polypropylene fibre

This paper investigates the incorporating of renewable lightweight bio-based aggregate (RLWBBA) in lightweight foam concrete (LWFC). The aim of this research is to incorporate different volume fraction (Vf) of polypropylene (PP) fibre into LWFC to determine the optimum compressive strength and splitting tensile strength. Four different mix was designed containing different percentage of PP replacement (0, 0.1, 0.2 and 0.3%). From the results, the compressive strength of the oil palm shell lightweight foamed concrete with 0.3% of macro polypropylene fibre (OPSLWFC/0.3) had showed the highest compressive strength and splitting tensile strength at 28 days, which are recorded at 4.01 MPa and 0.62 MPa respectively. It also showed the lowest density among all the mix design which is 1152 kg/m3 under demoulded condition. The OPSLWFC/0.3 has increased about 23.38% of 28 days compressive strength and 37.78% of splitting tensile strength compared to the control mix, which contains 0% of fibre proportion. Hence, the findings of this research revealed that the development of environmentally friendly lightweight foamed concrete can be used as an alternative solution for traditional lightweight concrete.

Pengaruh Limbah Beton sebagai Pengganti Agregat Kasar terhadap Kuat Tekan Beton

Concrete is the main material factor in a construction project field that is often used, because concrete has a high compressive strength value so it is very useful for structural buildings to withstand axial forces or compressive forces on the building itself where the structure can be used. for the long term. However, along with the increase in construction development in Indonesia, it has a negative impact on the environment around the construction site because with the rampant construction of this building it will trigger environmental pollution due to the remaining concrete waste from the construction project. On this basis, it encourages the author to conduct research by utilizing waste concrete as a substitute for coarse aggregate for the compressive strength of concrete, by reusing the concrete waste will increase the life of the material from the waste itself. In this study, the materials used were tested first, such as; cement density, silt content, water content, specific gravity absorption, wear testing and sieve analysis on aggregates. Then for the concrete mixture using concrete waste with variations of 0%, 25%, 50%, 75% and 100% of the total weight of coarse aggregate. In this study, the compressive strength at the age of 21 days with a mixture of 0%, 25%, 50%, 75%, and 100% concrete had a compressive strength of 200.92 kg/cm2, 188.83 kg/cm2, 206, respectively. 96 kg/cm2, 177.50 kg/cm2, and 179.01 kg/cm2. Then experienced an average shrinkage of 9.53 kg/cm2 at the age of 28 days. The optimum compressive strength is at 50% mixed variation, with a value of 206.96 kg/cm2 because it has an increase of 3% higher than normal concrete compressive strength with a mixing ratio of 1:2.5:3.5 and a slump value of ±13.25 cm and the dry weight of the concrete is 7.69 kg.

Rice Husk Ash-Based Geopolymer Binder: Compressive Strength, Optimize Composition, FTIR Spectroscopy, Microstructural, and Potential as Fire-Retardant Material.

Compressive strength is an important property in construction material, particularly for thermal insulation purposes. Although the insulation materials possess high fire-retardant characteristics, their mechanical properties are relatively poor. Moreover, research on the correlation between fire-retardant and compressive strength of rice husk ash (RHA)-based geopolymer binder (GB) is rather limited. In addition, previous studies on RHA-based GB used the less efficient one-factor-at-a-time (OFAT) approach. In understanding the optimum value and significant effect of factors on the compressive strength, it was deemed necessary to employ statistical analysis and a regression coefficient model (mathematical model). The objective of the study is to determine the effect of different material behavior, namely brittle and ductile, on the compressive strength properties and the optimum material formulation that can satisfy both compressive strength and fire-retardant properties. The factors chosen for this study were the rice husk ash/activated alkaline solution (RHA/AA) ratio and the sodium hydroxide (NaOH) concentration. Compressive strength and fire-retardant tests were conducted as part of the experiments, which were designed and analyzed using the response surface methodology (RSM). The microstructure of geopolymer samples was investigated using a scanning electron microscope (SEM). Results showed that RHA/AA ratio was highly significant (p < 0.000) followed by NaOH concentration (p < 0.024). When the RHA/AA ratio was at 0.7 to 0.8 and the NaOH concentration was between 12 and 14 M, high compressive strength above 28 MPa was recorded. Optimum compressive strength of approximately 47 MPa was achieved when the RHA/AA ratio and NaOH concentration were 0.85 and 14 M, respectively. Brittle samples with low Si/Al ratio of 88.95 were high in compressive strength, which is 33.55 MPa, and showed a high degree of geopolymerization. Inversely, ductile samples showed low compressive strength and degree of geopolymerization. Water content within the geopolymer binder had a major effect on its fire-retardant properties. Semi-ductile GB showed the best fire-retardant properties, followed by semi-brittle and brittle GB. Using RHA as an aluminosilicate source has proven to be a promising alternative.

Ant lion algorithm for optimal design of high performance concrete mixes

This paper presents the development of Ant lion optimization (ALO) models for optimal mix proportioning of high volume fly ash concrete (HVFAC). The development of the model came through in two steps, firstly, a modest data pertaining to 450 mix designs that are generated either in laboratory or in field were garnered from the literature were statistically analyzed and 350 appropriate mix designs were retained and necessary constraints, upper and lower bounds, and rational ratios are elicited. In the second step ALO algorithm was applied to determine optimal proportions of fly ash, cement, and water corresponding to optimum compressive strength of concrete. Optimal mix proportions were computed for five ranges of compressive strengths using the objective function and constraints farmed in the first step. The optimized mix proportions for all the strength ranges are found to be highly acceptable and corroborate very well with experimental values with mean square error ranging between 2% and 4%, 7%−13%, and 10–12.5% in case of water, fly ash and cement respectively. Further, a systematic comparison of results obtained by the author in implementing other bio inspired algorithms namely, Ant colony optimization (ACO), Elitist genetic algorithm (EGA), Honey bee optimization (HBO), and Particle swarm optimization (PSO) is also made. It is found that the quantities of the ingredients are almost identical, however with marginal differences in the mean square error metric. It is found that GA was bit high in errors, followed by ALO, ACO, and HBO not appreciable though. However PSO showed low errors in the range 1.6%−3.2%, 5%−10%, and 5%−8.5% in the optimized quantities in respect of water, fly ash and cement respectively across five strength ranges.

Effects of Steel Fibers (SF) and Ground Granulated Blast Furnace Slag (GGBS) on Recycled Aggregate Concrete.

Recycled aggregate is a good option to be used in concrete production as a coarse aggregate that results in environmental benefits as well as sustainable development. However, recycled aggregate causes a reduction in the mechanical and durability performance of concrete. On the other hand, the removal of industrial waste would be considerably decreased if it could be incorporated into concrete production. One of these possibilities is the substitution of the cement by slag, which enhances the concrete poor properties of recycled aggregate concrete as well as provides a decrease in cement consumption, reducing carbon dioxide production, while resolving a waste management challenge. Furthermore, steel fiber was also added to enhance the tensile capacity of recycled aggregate concrete. The main goal of this study was to investigate the characteristics of concrete using ground granulated blast-furnace slag (GGBS) as a binding material on recycled aggregate fibers reinforced concrete (RAFRC). Mechanical performance was assessed through compressive strength and split tensile strength, while durability aspects were studied through water absorption, acid resistance, and dry shrinkage. The results detected from the different experiments depict that, at an optimum dose (40% RCA, 20%GGBS, and 2.0%), compressive and split tensile strength were 39% and 120% more than the reference concrete, respectively. Furthermore, acid resistance at the optimum dose was 36% more than the reference concrete. Furthermore, decreased water absorption and dry shrinkage cracks were observed with the substitution of GGBS into RAFRC.

Effective utilization of waste eggshell powder in cement mortar

Solid waste management is one of the challenging issues faced by the developing countries. The developing countries find it very critical to manage the disposal of waste generation. India ranks 3rd in the production of egg, generating about 3.8 billion kilograms annually. This growth in the production of larger rate is mainly due to the hike in domestic consumption. This could lead to larger generation of solid waste. To overcome these issues, eggshells could be effectively incorporated into concrete production as cementitious blends. This paper investigates the suitability of pulverized eggshell powder as partial substitute to cement. The material characterization techniques like Scanning Electron Microscope (SEM) and X-Ray Diffraction (XRD) were used to investigate the feasibility of using eggshell powder. The study was conducted by producing cement mortars in the ratio of 1:3:0.5. Then the cement was partially replaced by pulverized eggshell at 5%, 10%, 15%, 20% by its weight. The fresh property was assessed using the flow table test, while the hardened property was determined using the compressive strength of the cement mortar at 7, 14, and 28 days. From the test results, 10% pulverized eggshell powder when utilized in mortar gives optimum compressive strength. The microstructural investigations proved to be evident for pulverized eggshell when replaced at 10% delivered good strength.

EFFECTS OF VARYING WATER-CEMENT RATIOS ON DIFFERENT GRADES OF CONCRETE USING LOCALLY MATERIALS

This research focused on laboratory tests that was conducted using locally available 10mm washed all-in gravel, quarry dust with varying water cement ratio. The research was carried-out using 108 (150 x 150 x 150) mm standard cubes that were all tested from three designed concrete mixes. In the present study, the role of water-cement ratio in compressive strength of concrete was investigated. The mixed concrete samples with water-cement ratios of 0.3, 0.35 and 0.40 were experimented for 3, 7, 21 and 28 days of curing. The results of compressive strength experiment showed that due to increase in water-cement ratio from 0.3 to 0.40, the compressive strength improved from 22 N/mm2 to 24.33 N/mm2 for 1:1.5:3 design mix, the compressive strength improved from 22.88 N/mm2 to 24 N/mm2 for 1:2:1 design mix, while compressive strength improved from 24 N/mm2 to 25.3 N/mm2 for 1:1:2 design mix respectively. The results for compressive strength experiments showed that the 0.4 water-cement ratio resulted in the optimum compressive strength for all three design mixes.&#x0D; &#x0D; &#x0D;

Optimization of Compressive Strength and Porosity of Mortars with Steel Scale by Grey Relational Analysis Method

İnşaat sektöründe betonun kalitesinin artırılması amacıyla çimentoya veya beton karışımı içerisine farklı malzemeler katılır. Fakat bu malzemeler bazen betonun bazı özelliklerini iyileştirirken bazı özelliklerini de ters yönde etkileyebilmektedir. Bu ilave malzemelerin beton üzerine olan etkilerinin tam olarak belirlenmesi amacıyla çok sayıda deneye ihtiyaç duyulmaktadır. Bu durum zaman ve malzeme kaybına neden olmaktadır. Bu çalışmada, demir-çelik endüstrisinin atık malzemelerinden biri olan çelik tufalin agrega olarak ilave edilmesi ile elde edilen harç numunelerindeki parametrelerin basınç dayanımı ve porozite üzerine olan etkileri incelendi. Bu parametrelerin optimizasyonu için Gri İlişkisel Analiz (GİA) yöntemi kullanıldı. Deney serilerinin belirlenmesinde dört parametreli L16 ortagonal dizininden faydalanılmıştır. Bu amaçla, farklı seviyelerde ince tufal, iri tufal, su/çimento oranı ve çimento dozajına sahip harç numuneleri hazırlanarak basınç dayanımı ve porozite değerleri elde edildi. Bu veriler Gri İlişkisel Analiz yöntemiyle değerlendirildi. Yapılan analizler sonucunda, optimum seviyeler ve basınç dayanımı ile porozite arasındaki ilişki belirlendi.

Mechanical performance, water and chloride permeability of hybrid steel-polypropylene fiber-reinforced recycled aggregate concrete

Environmental impact and inherit brittleness of conventional concrete can be reduced simultaneously by utilising recycled aggregates instead of natural ones and fiber-reinforcements. In this research, the effect of incorporating single steel fiber (SF) and polypropylene fibers (PPF) and hybrid SF-PPF was studied on the performance of recycled aggregate concrete (RC). Both single fibers and hybrid fibers were used at the volume fraction of 1%. Examined properties included compressive strength-fcm, flexural strength-fbm, ultrasonic pulse velocity-UPV, water absorption-WA, and rapid chloride permeability-RCP. The results revealed the use of single SF and hybrid SF-PPF in incredibly advanced the flexural performance of RC. Single SF-reinforced-RC or hybrid SF-PPF-reinforced RC showed markedly higher flexural strength than that of the conventional plain NC. The optimum compressive and flexural strength were obtained when plain NC and RC were reinforced with 0.85%SF-0.15%PPF. Flexural strength of RC reinforced with 0.85%SF-0.15%PPF was 26% higher compared to that of the plain-NC. The use of hybrid SF-PPF also reduced the water permeability capacity of RC better than the use of single SF or PPF. Hybrid fiber-reinforced RC has implications for cheaper and eco-friendly concrete than single SF-reinforced concrete.