High-strength Concrete Mixtures Research Articles

The Effect of Using Sustainable Copper Fiber on Some Mechanical Properties of High Strength Green Concrete

Finding an alternative to materials that pollute during manufacturing, most notably cement, is vital to executing the idea of sustainability in the building sector. It was vital to develop concrete that assists in the reduction of CO2 (Carbon dioxide) in the atmosphere because industrial wastes contain calcium, silica, and aluminous minerals, such as silica fume, that are employed in the production of high-strength concrete and have parameters that are identical to those of regular concrete. As a substitute for Portland cement, lime cement was utilized, and 15% of the cement's weight was substituted with silica fume. Environmentally friendly fibers (Copper Fiber) created from old electrical and electronic equipment were also employed. The purpose of the study is to produce High Strength Green Fiber Concrete (HSGFC) by incorporating silica fume as a replacement and study the effect of adding fiber on some mechanical attributes. The task needed the creation of a high strength concrete mixture of cement with a compressive strength of 65 MPa in accordance with ACI 211.4R, as well as the development of numerous experimental mixtures that relied on the findings of earlier researchers. The mechanical properties (compressive strength, flexural strength and split tensile strength) of samples are tested at 7, 28 and 60 days with standard curing. The results show that adding sustainable fiber to concrete mix enhances the mechanical properties such as compressive strength by 16% at 28 days, flexural strength by 35% and spilt tensile strength by 44% at 28 days Compared with concrete mix with no fiber. Also, the outcomes showed that it is feasible to develop High Strength Concrete (HSC) using sustainable copper fiber possessing exceptional stress resistance, tensile strength, and flexural strength.

Potential usage of fly ash and nano silica in high-strength concrete: Laboratory experiment and application in rigid pavement

High-strength concrete (HSC) using supplementary cementitious material of 30% fly ash (FA) and various nano silica (NS) contents were investigated in this study. FA and NS are waste materials collected from local thermal plants and rice husk ash in Southern Vietnam, respectively. Different concentrations of NS at 0%, 0.5%, 1.0%, and 1.5% were incorporated into the base mixture in place of cement and FA. The water-to-binder ratio of 0.32 was constant for all the mixtures. Results indicated that the combination binder of cement, FA, and NS satisfied the setting time as pure cement binder. The slump test value was in the range of 30–40 mm by adjusting the superplasticzer. Mechanical properties of HSC were studied at various curing ages of 3, 7, 28, and 56 days, including compressive strength, flexural strength, elastic modulus, and abrasion resistance. Results indicated that 1% NS can be considered as optimum content for preparing an HSC mixture, which showed the best mechanical properties. Furthermore, a good correlation between compressive strength and flexural strength was obtained from the results. Finally, rigid pavement calculation revealed that the addition of 1% NS resulted in a reduction in the thickness of the concrete slab by 30 mm (around 10.7%) compared to non-NS concrete. These findings suggest that incorporating nano-silica into concrete can lead to thinner concrete slabs with improved performance characteristics.

The resistance of high-strength concrete with ramie fiber using diatomaceous earth to high temperatures

This study was conducted to evaluate the visual appearance, mass change, and compressive strength degradation of high-strength concrete (HSC) with the addition of 0%, 0.15%, 0.30%, and 0.45% ramie fiber. The diatomaceous earth was used to substitute the cement at a 10% replacement level. The HSC specimens were prepared and exposed to different temperatures which were 400 °C, 500 °C, and 600 °C. The exposure time was 5 h. After the exposure, an assessment of visual appearance, measurement of mass, and testing of compressive strength were conducted. Specimens exposed to a temperature of 400 °C only had a color change in visual appearance. At a temperature of 500 °C and 600 °C cracks on the specimen surface began to appear. Specimen mass loss increased with increasing temperature. Moreover, HSC exposed to high temperatures also experienced a decrease in compressive strength in which the compressive strength degradation increased with increasing temperatures. HSC with 10% diatomaceous earth as cement replacement had smaller compressive strength, but better resistance to high temperatures. Meanwhile, the presence of ramie fiber in an HSC mixture improved the compressive strength but lowered the resistance to high temperatures.

Understanding the environmental, economic, and social impact of fly ash utilization on early-age high-strength mass concrete using life cycle analysis

High-strength mass concrete mixtures are a crucial component of numerous structures nowadays. However, concrete greatly impacts the environment, economy, and society. The impact of employing fly ash in early-age, high-strength mass concrete mixtures has not yet been quantified and documented in the literature. This study aims to evaluate the impact of early-age, high-strength mass concrete mixtures and provide insight into how the current practice might be enhanced to promote sustainability. The research examines concrete mix utilized in two bridges in the Philippines with the following design compressive strengths: 55 MPa at 7 days (7OPC), 55 MPa at 28 days (28OPC), and 55 MPa at 7 days with 20% fly ash as cement substitute (7FA20). Using SimaPro 9.3, a cradle-to-gate life cycle analysis was conducted to quantify their effects based on 18 midpoint and 3 endpoint categories. Results show higher impact of 7OPC on 17 midpoint and 3 endpoint indicators was observed than on 28OPC. The most significant midpoint impacts based on normalization are fossil resource scarcity, global warming potential, ozone formation, human carcinogenicity toxicity, and terrestrial ecotoxicity. The global warming potential of 7OPC was quantified to be 636 kg CO2 eq compared to 549 kg CO2 eq of 28OPC concrete. Utilizing fly ash decreased the damage to resources (11%), human health (16%), and the environment (16%). Analysis of concrete constituents indicated that using chemical admixtures to obtain early high strength contributed significantly to fossil resource scarcity and resource damage . The framework presented in this study may be used for assessing the sustainability of utilizing other waste materials in concrete production.

Structural behavior of beams cast using normal and high strength concrete containing blends of ceramic waste powder and blast furnace slag

In general, the use of ceramic waste powder (CWP) in concrete production is limited to few percentages (i.e., less than approximately 10–15% of Portland cement), given the resulting decrease in concrete strength and durability. This paper seeks to assess the relevance of blending CWP with blast furnace slag (BFS) to foster pozzolanic reactions and reinstate the drop in strength and structural performance of reinforced concrete (RC) members. Two categories of normal- and high-strength concrete (NSC and HSC) mixtures possessing 34 and 71 MPa compressive strengths are tested in this program. The RC beams measured 2-m in length and were differently configured by steel reinforcements to assess the flexural and shear strengths as well as the bond to embedded spliced rebars. Regardless of the steel configuration, results showed that the structural properties curtail when the concrete mixtures are prepared with 10% CWP replacement rate. This was attributed to a dilution effect and higher CWP porosity that detrimentally alter the concrete microstructure and strengths. The drop in flexural, shear, and bond strengths was found to be fully restored with the use of ternary binder composed of 55% cement, 35% BFS, and 10% CWP. Such results are in line with the improved concrete strength and durability, revealing the relevance of blending CWP with BFS to foster synergistic effects and reinstate the structural properties of NSC and HSC beams. Findings of this work can increase the CWP added-value for the construction industry, while reducing the cement carbon footprint.

The influence of cement substitution with rice husk ash on high-strength concrete

High-strength concrete is a crucial construction material in modern infrastructure development. It involves replacing some conventional raw materials with environmentally friendly alternatives to enhance concrete quality. Rice husk ash (RHA) is an agricultural waste that contains natural pozzolanic materials capable of improving the mechanical properties and strength of concrete. The use of rice husk ash (RHA) in high-strength concrete mixtures has the potential to reduce cement consumption and enhance crack resistance. The aim of this study is to investigate the impact of substituting cement with rice husk ash (RHA) and adding superplasticizer on the compressive strength of concrete. The targeted concrete strength is 45 MPa with variations of rice husk ash substitution at 5%, 10%, and 15% by weight of cement. This research obtained the compressive strength of concrete at 7 days with variations of 5% at 30.59 MPa, 10% at 25.20 MPa, and 15% at 20.77 MPa. Subsequently, at 14 days, the compressive strength increased with variations of 5% at 37.48 MPa, 10% at 27.56 MPa, and 15% at 22.23 MPa. The compressive strength continued to rise at 28 days, with variations of 5% at 44.26 MPa, 10% at 29.36 MPa, and 15% at 29.19 MPa.

Flexural Behavior of High Strength RC Beams Incorporating Nano-Silica and Macro-Polypropylene Fiber

This paper investigates the flexural behavior of high-strength RC beams experimentally to assess the effect of Nano-silica (NS) and Macro-Synthetic High Strength Polypropylene Fiber (MPF). Ordinary Portland cement was partially replaced by the NS and MPF with different proportions to produce four concrete mixtures. Tests were conducted on the full-scale high-strength RC beams, including first crack load, failure load, deflection, concrete strain, steel strain, and mode failure, which were examined and compared. In addition, the tests on the mechanical properties of high-strength concrete mixtures were also conducted at the ages of 28 and 56 days. The test results concluded that the addition of NS and MPF significantly improved the first-cracking and failure loads and decreased deflection at levels of cracking and failure loads. Additionally, an increase in NS content resulted in a minor increase in the ultimate strain related to the failure loads. Furthermore, the mix of 3% NS with 0.5% MPF was found to lead to the highest mechanical characteristics of concrete. The improvements were the concrete compressive strength by 33.6%, split tensile strength by up to 54.1%, and flexural strength by up to 28.3% compared with control specimens.

Axial compressive behaviour of thin-walled composite columns comprise high-strength cold-formed steel and PE-ECC

A new form of thin-walled composite columns, made of high-strength cold-formed steel (CFS) open sections and thin layers of engineered cementitious composites (ECC), is presented in this paper. The axial behaviour of columns with slenderness ratios (le/r) ranging between 10.08 and 13.86 under concentric loads were experimentally investigated. Twelve column specimens were divided into four groups of bare CFS columns, plain ECC columns, composite columns with SupaCee sections, and composite columns with Lipped-Cee sections. A specific ECC mixture with three PE-fibre contents: 0.75%, 1.75%, and 2.25% by mix volume, was placed in the tested columns in two thin thicknesses of 16.0 mm and 26.0 mm. Additionally, a high-strength concrete (HSC) mixture was utilised in two test columns for comparison with ECC. The results revealed that the composite CFS/ECC columns exhibited enhanced axial compressive capacities up to 2.79 times that of the bare CFS columns. The ductility indices and compressive toughness of the composite CFS/ECC columns were improved to 1.56 and 3.85 times those of the bare CFS columns, respectively. Strength prediction equations were developed based on the experimental observations to estimate the axial compressive capacity of composite CFS/ECC columns susceptible to local buckling.

Semi-circular bending setup for predicting fracture characteristics of high-strength fiber-reinforced concrete

Semi-Circular Bending (SCB) Setup is commonly used to investigate the fracture parameters of the road materials like asphalt mixtures. This paper examines the performance of the SCB setup in extracting the fracture characteristics of high-strength fiber-reinforced concrete (HSFRC). Monofilament and fibrillated polypropylene fibers with polyolefin coatings of 19, 30, and 50 mm length were added to a high-strength concrete mixture at three volume percentages of 0.5, 1, and 1.5 %. Standard cube and cylinder specimens were initially fabricated for conventional material properties tests. Subsequently, the three-point bending test specimens, i.e., intact rectangular beam, notched beam, and SCB, were made using the same concrete mix of different fibers lengths and percentages. A total of 36 beam and SCB tests with three replications was conducted to find the fracture energy and pick load of each specimen. Results showed that selecting the shortest fibers (19 mm) of 0.5 % and 1.5 % by volume increased the elastic modulus and the splitting tensile strength by 70.5 % and 43 %, respectively. Also, increasing the fiber length and volume enhanced the fracture energy of the notched beam and SCB specimens up to 90 times and 40 times, respectively. However, increasing the volume of the fibers was more effective than using longer fibers in fracture energy increase. For these three test setups, finite element models were generated and analyzed to develop a numerical framework capable of predicting the fracture characteristics of HSFRCs with acceptable accuracy (maximum error of 4 %). The concrete damaged plasticity (CDP) model in ABAQUS software package were adopted to simulate the damage initiation and progression in concrete using the material properties from the conventional tests. Comparing the results of beam setups with SCB tests, it was found that SCB can be a reliable and economical setup to find the fracture characteristics of the HSFRCs.

Effects of sugarcane bagasse ash and nano eggshell powder on high-strength concrete properties

There are many problems due to the cement industry around the world besides the air pollution by greenhouse gas emissions. The problem arises when a dense quantity of CO2 is emitted through the conversion of calcium carbonate lime (CaCO3) into calcium oxide lime (CaO), the main ingredient in cement. This transformation is made in an oven-dry by burning fossil fuels, in a process that releases more carbon dioxide. In this study, sugarcane bagasse ash (SCBA) and nano eggshell powder (NEP) are considered cementitious materials and were added to the cement at different percentages to reduce the cement contents in the concrete industry. Sixteen high-strength concrete (HSC) mixtures experimented with in this investigation contain SCBA and NEP other than the control mix. The SCBA and NEP were added to cement content by 5 %, 10 %, 15 %, and 20 % for SCBA, and 2.5 %, 5 %, and 7.5 % for NEP. This study evaluates the fresh and hardened properties of HSC. Also, EDX and SEM analyses were conducted on the SCBA, NEP, and HSC concrete to analyze the microstructure. The experimental results exhibited that the setting time of HSC is delayed by increasing the SCBA ratio by 25 % of the control mix. Adding NEP accelerates the HSC setting time compared with the control mix. The best mixture result includes 5 % NEP with 15 % SCBA, which exhibited a dense form, no pores, and no cracks, as analyzed in the microstructure.

Mathematical modeling techniques to predict the compressive strength of high-strength concrete incorporated metakaolin with multiple mix proportions

Many environmental and health problems are raised from cement manufacturing processes and other factories because those factories emit large amounts of carbon dioxide (CO2) into the atmosphere. Using supplementary cementitious material reduces the amount of cement used, then the amount of CO2 is also reduced. Metakaolin (MK) is used as a mineral admixture to improve the mechanical properties of concrete because higher strength requires a more densified concrete mixture. Mineral admixtures have a pozzolanic reaction and lower thickness of the transition zone. In this study, four different models, specifically linear regression (LR), nonlinear regression (NLR), multi-logistic regression (MLR), and M5P-tree models, are proposed to predict the compressive strength (compressive strength) of high-strength concrete (HSC) modified with metakaolin admixture. These models are useful since they serve as an effective way to predict compressive strength without waiting for a long time theoretically and are cost-effective and time-saving. For this purpose, 197 experimental data of HSC mixtures with MK from previous research are collected, statistically analyzed, and used to propose the prediction models. The curing time of the tested sample ranged between 1 and 360 days, and water to binder ratios was from 100-206 kg/m3. The highest compressive strength of the HSC samples was 105 MPa at 28 days. The proposed models are assessed by the coefficient of determination (R2), root mean squared error (RMSE), scatter index (SI). And OBJ. The M5P-tree model was the best model among the proposed models with R2, RMSE, SI of 0.77, 6.67 MPa, 0.096, respectively.

OPTIMALISASI PENGGUNAAN PASIR BESI SEBAGAI PENGGANTI AGREGAT HALUS DALAM CAMPURAN BETON MUTU TINGGI

Infrastructure progress needs to be supported by the development of research on construction material technology, one of which is concrete technology. With its various advantages, concrete is continuously used to solve infrastructure problems. However, it also has impact on the use of large-scale materials and has the potential to deplete natural resources if not handled properly. One material that can be used as an alternative is iron sand. Iron sand is a mineral resource with magnesium content and has characteristics as a substitute for fine aggregate in concrete mixes. This study aimed to determine the effect of iron sand as a substitute for fine aggregate in high-strength concrete mixtures. This research method was a laboratory experiment by testing the characteristics of high strength concrete, namely compressive strength, tensile strength, and modulus of elasticity. This study found that the optimum concrete compressive strength occurred in the V-02 sample with a result of 51.71 MPa from the design compressive strength (fcr) = 45 MPa. The optimum tensile strength test occurred in the V-02 sample with a result of 4.13 MPa, and the optimum elasticity modulus test occurred in the V-02 sample producing 28684.37 MPa

Mechanical Properties of Hybrid Steel-Polypropylene Fiber Reinforced High Strength Concrete Exposed to Various Temperatures

Combining different types of fibers inside a concrete mixture was revealed to improve the strength properties of cementitious matrices by monitoring crack initiation and propagation. The contribution of hybrid fibers needs to be thoroughly investigated, taking into consideration a variety of parameters such as fibers type and content. In this paper, the impact of integrating hybrid steel-polypropylene fibers on the mechanical properties of the concrete mixture was investigated. Hybrid fiber-reinforced high-strength concrete mixtures were tested for compressive strength, tensile strength, and flexural strength. According to the results of the experiments, the addition of hybrid fibers to the concrete mixture improved the mechanical properties significantly, more than adding just one type of fiber for specimens exposed to room temperature. Using hybrid fibers in the concrete mixture increased compressive, tensile, and flexural strength by approximately 50%, 53%, and 46%, respectively, over just using one type of fiber. Furthermore, results showed that including hybrid fibers into the concrete mixture increased residual compressive strength for specimens exposed to high temperatures. When exposed to temperatures of 200 °C, 400 °C, and 600 °C, the hybrid fiber reinforced concrete specimens maintained 87%, 65%, and 42% of their initial compressive strength, respectively. In comparison, the control specimens, which were devoid of fibers, would be unable to tolerate temperatures beyond 200 °C, and an explosive thermal spalling occurred during the heating process.

Behavior of eccentrically loaded hybrid fiber-reinforced high strength concrete columns exposed to elevated temperature

The aim of this study is to evaluate the effect of elevated temperature on the properties of hybrid fiber reinforced high strength concrete (HFRHSC) and columns under eccentric loading. For this purpose, seven high-strength concrete (HSC) mixtures were prepared, one mixture without fiber and six mixtures containing steel fiber (SF), polypropylene fiber (PP), glass fiber (GF), (SF + PP), (SF + GF), and (GF + PP). Fourteen HSC columns were cast (i.e. two columns for each mixture) and tested under eccentric loading with an eccentricity ratio of (e/t = 0.75). Seven columns were kept at room temperature and the other seven were tested after being exposed to 600 °C for 1 h. The experimental results indicated that addition fibers lead to an increase in compressive, tensile and flexural strengths of HSC, while the influence of PP and GF fibers is insignificant in an increase of compressive strength. The elevated temperatures had an adverse influence on the mechanical properties of HSC. The results also revealed that HSC columns containing fibers had ultimate loads, ultimate moment capacities, toughness and temperature resistance higher than those of HSC concrete columns without fibers. The ultimate load, ductility and toughness decreased after exposure to elevated temperature. Finally, the load-moment (P-M) interaction diagrams of the tested columns were generated theoretically to compare the experimental results with theoretical ones.

Effect of treated wastewater on properties of high strength concrete mixture

Effect of treated wastewater on properties of high strength concrete mixture

Compressive strength of SF and FA based self curing HSSC: An experimental study

Typical High-strength concrete (HSC) mixtures are characterized by low water-cementitious material ratio, high content of cementitious material, and the incorporation of admixtures. Concrete needs a favourable atmosphere by providing moisture for a minimum base period of 28 days for hydration and to attain targeted strength. In the present scenario of water scarcity, the water required for curing concrete is a troublesome constraint. Self-curing concrete is one of the peculiar concretes for coping with insufficient curing caused by human error. The prime goal of this study is to identify the self-curing compound’s optimum dosage for High Strength Self-Compacting Concrete (HSSC). Likewise, it is aimed to investigate the compressive strength characteristics of HSSC. For the study, a self-curing agent namely “PEG-400” with varying percentages (0.5%, 1%, 2% & 3% by weight of cement) was investigated. An attempt was made to identify the effect of the self-curing compound on the fresh and hardened properties of HSSC, workability tests and compressive strength tests were conducted. The tests on hardened concrete were conducted after curing for 28 days for conventional HSC specimens and ambient curing for HSSC. It was observed that with the addition of 1% of PEG-400 self-curing compound, the compressive of HSC was found to be increased by 1.86% in comparison with the conventionally cured HSC. It was observed that with the addition of 1% of PEG-400 self-curing compound, the compressive strength of HSSC was found to be increased by 1.87% in comparison with the conventionally cured HSSC.

Study on Workability High Strength Concrete Containing Pineapple Leaf Fiber (PALF)

The addition of fibers in concrete increases bridging force in interfacial transition zones inside the concrete matrix. Pineapple Leaf Fiber (PALF) is a natural fiber that has the potential to replace artificial fibers as reinforcement on concrete. As reinforcement fiber in concrete, PALF will undergo fibrillation and water absorption in concrete mixture and will change the mechanical properties of fresh concrete. So, the purpose of this study is to study the workability characteristics of fresh state concrete given PALF. Some variations of PALF composition are 0.04, 0.09, and 0.15 % wt. of cement is mixed into fresh concrete mixture with water-cement (w/c) ratio variations of 0.35, 0.38, and 0.41. The planned concrete is high-strength concrete, then the provisions of determination of coarse and fine aggregates using sieve analysis according to high-strength concrete material standards and concrete mixtures are given superplasticizer 0.09% wt. of cement constantly for all mixtures. A slump test method is still an option in this study, where this method becomes the standard to determine workability effectively. The results showed that an increase in concrete strength was achieved in the addition of PALF composition in concrete compared to control (normal concrete), in addition to the tendency of the relationship between w/c ratio, slump value, and compressive strength in all PALF variations achieved in this study.

Evaluating the Use of Eggshell Waste Ash in High Strength Concrete

This study aims to determine the effect of incorporating eggshell waste as partial compensation from Portland cement material on high-strength concrete mixtures' performance. The properties studied are workability, compressive and flexural strengths, water absorption, dry density, and thermal conductivity. In the same trend, the environmental impact of the replacement mentioned above is evaluated. Four different weight percentages (0%,5%,10%,15%, and 20%) of the cement were replaced with eggshells ash. The results indicate that the incorporation of eggshell powder improves the compressive strength and flexural strength by about 14.7% and 6.5%, respectively, at 28days age over control concrete mixes at 15% replacement. The optimum replacement ratio was found to be 15% based on the strength. Furthermore, the results showed a reduction in water absorption and thermal conductivity as 15% of eggshell ash was used as a replacement by cement weight with 10.7% and 10.65 respectively, besides the reduction in the amount of cement used in the mixture. These results are positively reflected in supporting natural resources' sustainability and depleting the ozone layer by reducing the emitted gases.

Influence of pumping on the resistivity evolution of high-strength concrete and its relation to the rheology

The pumping process exerts high pressure and strong shearing on fresh concrete, which may affect the hydration process and rheological behavior of concrete. In this paper, full-scale pumping circuits with lengths of 348-, 600-, and 924-m were established to evaluate the effect of pumping on hydration and rheology of concrete. Electrical resistivity measurement was employed to indirectly evaluate the hydration process of concrete. Ten high-strength concrete (HSC) mixtures with slump flow of 680 ± 50 mm and strength grades of C60-C100 were pumped, and HSC mixtures were sampled before and after pumping for rheological properties and electrical resistivity measurements. Findings indicated that the hydration process, determined by the electrical resistivity evolution, was accelerated after pumping. The end of the dormant period of fresh concrete was decreased by 10.3%-27.3%, and the end of the setting period was shortened by 15.6%-28.4% after pumping. The reduction in the dormant period can be well correlated with the drop in slump flow or increase in dynamic yield stress after pumping.

STRENGTH TESTS OF CONCRETE CUBES WITH ADDITION OF ANTHROPOGENIC WASTE

The authors have studied the development of a high-strength concrete mixture for manufacturing reinforced concrete products, in particular, the bar lintels. Dump fly ash of the Pavlodar CHPP-1 has been added as man-made waste. The paper presents the results of testing the concrete cubes strength with addition of industrial waste. The test results show the possibility of using anthropogenic waste for concrete mix in manufacturing bar lintels. In this case, the longer the hardening time, the higher the concrete mixture strength. By planning the experiment, a linear mathematical dependence of the concrete strength on such studied factors as cement, man-made waste and water, was obtained. The adequacy of the obtained model is confirmed by comparing the tabular and calculated values of the Fisher coefficient, as well as the coefficient of determination, which in practice varies for mixtures in the range from 0.7 to 0.8. According to the Pareto diagram, it is determined that all the factors are important, but the first component, i.e. cement consumption has the greatest effect. As a result, it was found that the addition of 10 % of man-made waste can reduce cement consumption by 10 % and increase the product strength by 20 %.