Workability Of Self-compacting Concrete Research Articles

Effect of various fibers and rice husk ash on the workability of self-compacting concrete

AbstractThe study aims to investigate and find natural fiber as concrete reinforcement using the self-compacting concrete method. Methods of adding fiber and self-compacting concrete methods are exciting because these two methods have different characteristics and advantages. Therefore, the performance of the fresh-state flow capability of the self-compacting concrete method, which contains various fibers, was observed. Coconut fiber, pineapple leaf fiber, ijuk sugar palm fiber, and artificial polypropylene fiber were used with varying compositions of 0.3, 0.5, and 0.7% by mass of binder. The results show that coconut and pineapple fiber concrete met the European Guidelines for Self-Compacting Concrete standards. The coconut and pineapple fiber concrete performed admirably in all tests.

An Experimental Analysis on Self Compacting Concrete with Different Grades

Abstract: Self-compacting concrete (SCC), moreover called self-consolidating concrete. It is able to stream beneath its possess weight to totally fill the formwork and accomplish total compaction, indeed within the case of over-burden fortification. Solidified concrete is thick, homogeneous and has at slightest the same specialized properties and toughness as conventional vibrated concrete. scc can be made utilizing the same fixings as customary concrete. In any case, a more tightly resistance is required to guarantee tight control of processability characteristics. The dosing of self-compacting blend is much more logical than that of standard concrete blends. SCC blend requires tall powder substance, less coarse total, exceedingly viable superplasticizer and VMA (viscosity modifying agent) to provide concrete blends soundness and fluidity. Workability of SCC could be a adjust of ease, deformability, fill capacity and isolation resistance.

The effect of using treated domestic wastewater with different pHs on workability, mechanical, and durability properties of self-compacting concrete.

In the present work, we used treated domestic wastewater with different pHs in self-compacting concrete (SCC) to find the effect of treated wastewater with different pHs on the workability, mechanical, and durability properties of SCC. Eight different SCC mixtures were designed, including two control samples using tap water with a water-to-cement ratio (W/C) of 0.5 with 400 kg/m3 of cement and W/C of 0.36 with 440 kg/m3 of cement. Six SCC samples with the same characteristics as control samples except using treated domestic treated wastewater with different pHs. The results indicate that the workability of the SCC sample using the treated domestic wastewater in acidic pH was higher than the alkalinity state. Using treated domestic wastewater instead of tap water in SCC samples decreased compressive, flexural strength, and fracture toughness by less than 10%. Also, carbonation, 30-min water adsorption, and capillary water adsorption of SCC samples increased when treated domestic wastewater was used. The compressive strength of SCC samples made with treated domestic wastewater in an acidic state is less than about 5% in an alkaline state. The energy dispersive spectroscopy and the scanning electron microscope images confirmed that using treated wastewater instead of tap water, in SCC samples, reduced compressive strength because the Ca/Si ratio increased when treated domestic wastewater was used. The SCC samples with treated domestic wastewater in the alkaline state have a lower Ca/Si ratio. The higher compressive strength belongs to concrete samples that used treated domestic wastewater in an alkaline environment with a lower Ca/Si ratio.

Impact of superabsorbent polymer on self-compacting concrete's workability, strength, carbonation and freezing-thawing

Superabsorbent Polymer, an internal curing material, is a significant development in concrete technology. Self-compacting concrete is popular due to high flowability or pumpability. However, the higher quantity of cementitious materials required higher moisture consumption to complete the hydration. Further moisture unavailability leads to shrinkage increment. External curing cannot give proper moisture to cementitious material at higher depth. Hence, internal curing with super absorbent polymer is an economical solution for this problem. This study examines the impact of super absorbent polymer on the mechanical and durability properties of concrete. Laboratory tests were conducted to evaluate the workability, mechanical characteristics of the concrete, such as compressive strength and flexural strength. In addition, freezing-thawing tests and carbonation tests were conducted to investigate the durability performance of concrete. Scanning electron microscopy images were also used to observe the concrete's microstructure after freezing-thawing cycles. The findings demonstrate that Compressive strength and flexural strength values decreased in water curing while in air curing, those were increased. Additionally, it was discovered that the freezing-thawing cycles decreased the compressive strength of reference concrete in standard water curing. However, compressive strength increased after freezing-thawing cycles in air-curing super absorbent polymer mixes. Scanning electron microscopy images have confirmed that the microstructure of air-curing super absorbent polymer mixes was improved

Experimental Study on Direct Shear Strength of Fiber Reinforced Self Compacting Concrete under Acid and Sulfate Attack

This study primary is to investigate the shear strength of self-compacting concrete (SCC) reinforced by steel-fiber (SF) and polypropylene-fiber (PPF) in different environmental conditions: the air, sulfate (MgSO4 with a concentration of 5%) and acid (H2SO4 with a concentration of 5%). The study also examines the effect of fiber volume fraction on the workability, shear strength, compressive strength, and splitting tensile strength of fiber reinforced SCC. The article aims to determine the durability effects of both fibers and their resistance to aggressive environmental conditions. The contribution of this article is an experimental investigation on the shear strength of SCC reinforced by SF as well as PPF in 3 different environmental conditions after 30 days of exposure. The study also investigated the fresh and mechanical properties of 5 different mixtures of SCC with/out 0.1% and 0.2% fibers. The study also concluded that PPF decreased the workability of SCC badly, and special care must be taken when selecting its volume fraction. Also, it was found that generally shear strength of SCC mixes enhanced with increasing SF and PPF volume fraction. Moreover, it was found that both fibers have good durability effects, and resist aggressive environmental conditions, with the best results obtained from samples containing 0.2% SF. In the air condition, while the compressive strength, shear strength and tensile strength results were 52.6MPa, 6.43MPa and 3.91MPa, in the sulfate condition those were 46.37MPa, 6.55MPa and 3.59MPa, and in the acid condition those were 34.4MPa, 5.5MPa and 3.46MPa, respectively.

Study on the bulk density and influencing factors of green ferronickel slag self-compacting concrete aggregates

The compactness of aggregates has a significant impact on the workability of self-compacting concrete. The bulk density of aggregates is an effective parameter for evaluating the compactness of aggregates, reflecting the degree of compactness of the aggregate system. This study aims to explore the theoretical calculation model and application of the bulk density of green ferronickel slag as aggregates in self-compacting concrete. The influence of different particle size distributions and ferronickel slag content on the bulk density of the aggregate system was analyzed. Based on the calculation method of the maximum bulk density of aggregates, the bulk density of the aggregate system was calculated for different particle size distributions and nickel-iron slag content, and the effect of nickel-iron slag content on the compactness of the aggregate system was analyzed.

“The Exploration of a Double and Ternary Composite of Self-Compacting Concrete with Metakaolin and GGBS’’

Self-Compacting Concrete (SCC) is a modern form of concrete that does not involve vibration it during laying or compaction operations. The use of fine materials such as Metakaolin (MK) and GGBS can ensure the required concrete property. One possibility for minimising the cost of self-compacting concrete is to employ mineral admixtures such as Metakaolin and GGBS. It also lowers the heat of hydration. This study adopted (OPC 53) and M30 grade of concrete. In the first trail, MK was kept constant at 5% while GGBS was varied starting at 30% with increments of 5% (30%, 35%, and 40%). In the second trail, MK was kept constant at 10% while GGBS was varied starting at 30% with increments of 5% (30%, 35%, and 40%) replacement by the weight of Portland cement, and performance is assessed and compared to conventional concrete mix. The effect of mineral admixtures on self-compacting concrete workability, compressive strength, splitting tensile strength, flexural strength, and modulus of elasticity, With a water cement ratio of 0.47 and manufacturing sand as fine aggregates and 12.5 mm coarse aggregates, a powder content of 520 kg/m3 (as per IS code10262-2019) is chosen as the binder material (Fine aggregate and cement) To improve the flow of the concrete, the superplasticizer poly carboxylate ether was used. As a result, self-compacting concrete's flow and filling capacities have significantly improved. MK5 (double blended mix) and MK5 + GGBS35 (triple blended mix) have higher 28-day strength than other mixes, while MK5 + GGBS35 has a higher modulus of elasticity than other mixes.

Workability and mechanical properties analysis of hybrid fibers reinforced self-compacting concrete incorporating recycled aggregates based on acoustic emission technique

This research focused on maximizing the utilization of recycled aggregates to produce hybrid fibers reinforced self-compacting concrete (SCC) suitable for the majority of construction applications. Hybrid fibers, including milling profiled steel fiber with the volume fraction of 1.0 % and polypropylene fiber with the volume fraction of 0.1%, and mineral admixtures were used to improve the mechanical properties and workability of SCC with recycled aggregates, respectively. The influence of recycled coarse aggregate (RCA) and recycled fine aggregate (RFA) in different replacement ratio combinations (25%-0%, 50%-0%, 75%-0%, 100%-0%, 0%-25%, 0%-50%, 25%-25%) on the workability and mechanical properties of hybrid fibers reinforced recycled aggregates SCC (HFRA-SCC) were studied. The acoustic emission (AE) and digital image correlation (DIC) technique were used to monitor the crack development of HFRA-SCC under compression and splitting tensile loading, respectively. Results showed that both RCA and RFA had negative effects on the workability of HFRA-SCC when their replacement ratio exceeded 25% respectively. The mechanical properties of HFRA-SCC decreased with the increase of recycled aggregates replacement ratio as well, while fibers could compensate the strength loss caused by recycled aggregates and significantly increase the toughness of HFRA-SCC. A larger number of AE activities, as well as a sudden spike in cumulative AE energy, could predict the failure of specimen in advance. According to the analysis to the experimental results of this paper, the maximum replacement ratio of recycled aggregates used in HFRA-SCC was proposed.

Piezoresistivity in self-compacting concrete mixes with hybrid additions of carbon fibers and nanofibers

Self-sensing properties of concrete structures can be achieved through the incorporation of additions in carbon-based materials (CBM) that modify electrical properties and provide piezoresistive (PZR) properties to the cement paste. PZR in pastes and mortar mixes with different types of carbon-based materials such as fibers of different sizes has been extensively tested. However, very limited studies on self-sensing properties in concrete are available due to the lower content of paste volume that leads to a decrease of concrete PZR. However, self-compacting concrete (SCC) can be an ideal candidate to implement PZR, due to two fundamental traits: the larger amount of paste of SCC compared to a conventional concrete and larger volumetric fraction of fiber can be incorporated due to a reduced effect on SCC workability and consistency. The present study aims to assess PZR properties of SCC with carbon-based components of different sizes. Combining carbon nanofibers (NFC) and carbon fibers (CF), in hybrid systems, could lead to obtain SCC with self-sensing properties identifying their effectiveness thresholds. The self-detection performance of PZR-SCC samples under mechanical stress was verified by resistivity and PZR experimental tests.

Performance of SCC Concrete with Additional Materials of Rice Husk Ash

Concrete with high ductility, workable, high strength, easy to flow without compaction, and durable is a concrete need in the future. Concrete with this quality, one of which is to make self-compacting concrete (SCC). This paper reports performance of self compacting concrete (SCC) containing rice hush ash. Rice husk ash is waste from burning rice husks. The purpose of this study was to determine the performance of SCC concrete with the addition of rice husk ash. SCC specimens were made using rice husk ash (RHA) and SCC without rice husk ash (NRHA). The specimens were made with water cement ratio 0.30. Superplastisizer used is a type Naptha 511P. The result indicated that the workability of SCC containing rice hush ash (RHA) more workable compare SCC without rice hush ash (NRHA). The initial setting time of SCC with rice hush ash more slowly compare SCC without rice hush ash. The compressive strength, flexural strength, and tensile strength of SCC RHA mor higher compare SCC without RHA (NRHA). The tensile strength value of RHA and without RHA concrete meets the tensile strength requirements of RSNI T-12-2004.

Optimization of Graphene Oxide Incorporated in Fly Ash-Based Self-Compacting Concrete

Self-compacting concrete (SCC) was developed to overcome the challenges of concrete placement in dense or congested reinforcement structure, where the concrete can flow under its own weight to fill the densely reinforced structure. However, production of SCC mostly involves the use of high cement to achieve the desired strength. Therefore, to reduce the needed amount of cement, pozzolanic materials such as fly ash can be used to partially replace cement. However, fly ash has been reported to decrease the strengths of concrete especially at early ages. In this study, a self-compacting concrete (SCC) was developed with fly ash as a basic replacement material considering the efficiency of fly ash and incorporating graphene oxide (GO) as a cement additive to counteract the negative effect of fly ash. Response surface methodology (RSM) was utilized for designing the experiments, investigating the effects of fly ash and GO on SCC properties, and developing mathematical models for predicting mechanical properties of SCC. The ranges of fly ash and graphene oxide were 16.67 to 35% and zero to 0.05%, respectively. Statistical analysis was performed by using Design Expert software (version 11.0, Stat Ease Inc., Minneapolis, MS, USA). The results showed that fly ash had a positive effect while GO had a negative effect on the workability of SCC. The incorporation of fly ash alone decreased the compressive strength (CS), splitting tensile strength (STS) and flexural strength (FS), and additionally, increased the porosity of SCC. The addition of GO to fly ash-based SCC reduced its porosity and enhanced its mechanical strengths which was more pronounced at early ages. The developed models for predicting the mechanical strengths of fly ash-based SCC containing GO have a very high degree of correlation. Therefore, the models can predicts the strengths of SCC using fly ash and GO as the variables with a high level of accuracy. The findings show that based on the EFNARC guidelines, up to 35% of fly ash can be used to replace cement in SCC to achieve a mix with satisfactory flowability and deformability properties

Explainable Ensemble Learning Models for the Rheological Properties of Self-Compacting Concrete

Self-compacting concrete (SCC) has been developed as a type of concrete capable of filling narrow gaps in highly reinforced areas of a mold without internal or external vibration. Bleeding and segregation in SCC can be prevented by the addition of superplasticizers. Due to these favorable properties, SCC has been adopted worldwide. The workability of SCC is closely related to its yield stress and plastic viscosity levels. Therefore, the accurate prediction of yield stress and plastic viscosity of SCC has certain advantages. Predictions of the shear stress and plastic viscosity of SCC is presented in the current study using four different ensemble machine learning techniques: Light Gradient Boosting Machine (LightGBM), Extreme Gradient Boosting (XGBoost), random forest, and Categorical Gradient Boosting (CatBoost). A new database containing the results of slump flow, V-funnel, and L-Box tests with the corresponding shear stress and plastic viscosity values was curated from the literature to develop these ensemble learning models. The performances of these algorithms were compared using state-of-the-art statistical measures of accuracy. Afterward, the output of these ensemble learning algorithms was interpreted with the help of SHapley Additive exPlanations (SHAP) analysis and individual conditional expectation (ICE) plots. Each input variable’s effect on the predictions of the model and their interdependencies have been illustrated. Highly accurate predictions could be achieved with a coefficient of determination greater than 0.96 for both shear stress and plastic viscosity.

Development of a Mix Design Method for Multiplexed Powder Self-Compacting Concrete Based on the Multiscale Rheological Threshold Theory

The multiscale rheological threshold theory can guide the mix design of self-compacting concrete (SCC) from a trans-scale view. Through the paste thresholds calculated by the mini-slump flow test results, the workability of SCC can be predicted. However, this method shows insufficient prediction accuracy when handling multiplexed powder. In the existing threshold calculation formula, the characteristics of powder materials were described through empirical values, without considering the specific properties of various powders. This paper focuses on the application of the multiscale rheological threshold theory to multiplexed powder SCCs. Through the research on the characteristics of powder materials, especially D50 and Span, the effect of the powder properties on paste thresholds was carried out. The prediction accuracies were confirmed by four sets of self-compacting mixtures at paste and concrete scales and were verified with another set of tests. There are a total of 45 paste and 45 SCC test results with multiplexed powders, including cement, fly ash, and limestone powder. The predicting accuracies are expressed as the relative accuracy ε and the accuracy index ε′, calculated by the comparison of self-compacting zones at paste and SCC scales. The calculation results showed that ε and ε′ of the modified method increased. This modified method can be efficient for the mix design of SCC containing multiplexed powders.

Influence of Marble Powder and Polypropylene Fibers on the Strength and Durability Properties of Self-Compacting Concrete (SCC)

The purpose of this study was to investigate the effect of polypropylene fiber reinforced self-compacting concrete (SCC) at both the fresh and hardened stages, as well as their durability behavior. Properties of marble powder-based fiber reinforced SCC at fresh state were studied by means of slump flow diameter and flow time, V-funnel, and L-box test. The concrete properties at the hardened state were examined regarding compressive strength, split tensile strength, and flexural strength. Cement was replaced with marble powder with a substituting ratio of 4%, 8%, 12%, and 16% while polypropylene fibers were added as 0.1%, 0.2%, 0.3%, and 0.4%. The durability properties were analysed in the form of water permeability and chloride migration. In accordance with the outcomes of the tests, the workability of SCC deteriorated with an increase in fiber content, although it performed effectively at higher marble dosages. There was little impact of fibers on compressive strength and water permeability property of SCC. However, by adding the fibers in SCC improved both the split tensile strength and flexural strength by 16.92% and 11.36%, respectively. The addition of marble powder showed a synergetic effect with polypropylene fibers, which showed its applicability in SCC. The chloride resistance was improved at lower content of polypropylene fiber addition. For optimizing polypropylene fibers (pp) and marble powder substitution, the polynomial work expectation justifies the response surface technique (RSM). When a p value of 0.05 is used to analyse the variation in the (Linear-ANOVA), the model is considered statistically significant. Performance of concrete was greatly enhanced by substituting 12% marble powder with cement and adding 3% polypropylene fiber.

Properties of fresh and hardened self-compacting concrete incorporating rice husk ash: A review

Abstract Rice husk is considered as a waste product of farming. However, rice husk ash (RHA) has a good pozzolanic activity, which can be used in cement-based materials as a supplementary cementitious material (SCM), and it is also suitable for self-compacting concrete (SCC). This study reviews the physical and chemical properties of RHA and the properties of RHA–SCC mixtures such as fresh properties (crucial factors and evaluation methods of workability for fresh SCC), mechanical properties (compressive strength, splitting tensile strength, flexural strength, and modulus of elasticity), and durability (water absorption and sorptivity, acid resistance, chloride penetration resistance, electrical resistivity, and alkali silica reaction). It was observed that the workability of SCC decreases with an increase in the incorporation rate of RHA. An incorporation rate of RHA in the range of approximately 15–20% enhances the mechanical properties and durability of SCC. The incorporation of RHA into SCC can reduce the environmental burden of rice husk treatment, and promote sustainable development of cement industries and reduce the cost of SCC.

Application of powdered bio-composites in the field of self-compacting concrete: A review

Cement manufacture accounts for 5% of worldwide carbon dioxide emissions, resulting in significant environmental issues, and using supplemental cementitious materials (SCM) is an efficient strategy to minimise cement consumption. Self-compacting concrete (SCC) often relies on high amounts of binder and chemical additives to maintain workability. Thus, reducing the embodied carbon of SCC materials becomes essential for its wider application. Powdered bio-composites (PBCs), such as rice husk ash (RHA), bagasse ash (BA), palm oil fuel ash (POFA), groundnut shell ash (GSA), and eggshell ash (ESA), can be utilised as SCM for SCC. This paper systematically reviewed the physical properties, chemical properties, and heat treatment methods of five types of PBCs and their impacts after replacing cement in SCC. The review disclosed that heat treatment could effectively reduce the value of loss on ignition (LOI), thus ensuring the activity of PBCs. High-temperature, short-duration incineration or low-temperature incineration for a long time can be effective. The review revealed that adding the five types of PBCs will reduce the workability of SCC, and RHA has the greatest negative impact. Segregation occurs when the cement replacement rate with RHA exceeds 20%. All five types of PBCs improve the mechanical properties of SCC to a certain extent after replacement. The preferred replacement rates are 5%-20% for RHA, BA and GSA, while for POFA the preferred rate could exceed 30%. The preferred rate is not conclusive for Eggshell ash, as it may lead to either positive or slightly negative impacts regarding compressive strength. In addition, adding an appropriate amount of PBCs will increase the durability of hardened SCC. The summarised impacts were also correlated with the microstructure of SCC through various analysis tools. The paper reveals the current gaps in applying PBCs in SCC and proposes strategies to design environmentally friendly SCC containing PBCs.

Development of Self-Compacting Concrete of Grades M25, M30 and M35 Using Composite Cement

Abstract: Both fly ash and slag are industrial by-products and their disposal has become a serious environmental problem. Considering their excellent cementitious properties, their utilization in the cement industry becomes crucial. Because of the significant contribution to the environmental pollution, over dependency on cement has to be reduced. There is a need to economize the use of cement, thus, the concept of composite cement becomes necessary. In this study, Fly Ash (FA) and Ground Granulated Blast Furnace Slag (GGBFS) were used as partial replacement of cement to improve the properties of selfcompacting concrete (SCC). Three SCC grades viz., M25, M30 and M35 were made in the laboratory. For all the three grades, two variations were considered. Case 1 included 65% Ordinary Portland Cement (OPC), 15% FA and 20% GGBFS while case 2 included 85% OPC and 15% FA. In order to improve the workability of SCC, certain amount of super-plasticizer was added in the design mix. Vfunnel, L-box and slump flow tests were conducted on fresh SCC whereas compressive strength, flexural strength and split tensile tests were performed on hardened SCC. The results showed that the optimum admixture content was used their respective grades and cases leading to negligible segregation. Moreover, all the design mixes satisfied the SCC workability conditions comfortably. It was concluded that by replacing cement partially with fly ash and GGBFS in percentages mentioned in cases 1 and 2, the tensile strength of SCC could improve. From the 28 days results obtained from the compressive strength test, it was inferred that 15% fly ash and 20% GGBFS could be partially replaced with cement for all the grades i.e., M25, M30 and M35. This, could help in reducing the reliance on cement, and utilizing the industrial by-products in a better way. Keywords: Self-Compacting Concrete (SCC); Ordinary Portland cement (OPC); Fly Ash (FA); Ground Granulated Blast Furnace Slag (GGBFS); Workability; V-funnel; L-box; slump flow; compressive strength test; split tensile strength; flexural strength

ECO FRIENDLY HIGH EARLY STRENGTH SELF COMPACTING CONCRETE USING KAOLIN AND WASTE MARBLE DUST

The growth and development of infrastructure in Indonesia is currently growing very rapidly, and the cement production process produces the second largest amount of carbon dioxide after waste, which plays an important role in the current global warming. Self compacting concrete is one of the biggest innovations in the field of construction, Self compacting concrete is one of the biggest innovations in the construction field, where this concrete has high workability but does not ignore compressive strength. Therefore, new, sustainable materials are needed to replace cement production, but they are also required for the workability required to make self-compacting concrete. Green concrete concept, the use of kaolin, and marble dust waste, can be a solution to replace some cement. This innovation research uses XRF or X-ray fluorescence methods to identify and analyze the constituent elements of self-compacting concrete innovations. In this study, self-compacting concrete was obtained using (marble dust waste) which replaced 15% cement, and kaolin which replaced 10% concrete waste. with the main element calcium oxide (CaO) and containing (SiO) can be used as an additive or partial replacement of cement in the manufacture of concrete and kaolin can be obtained from kaolin mines spread across Indonesia, and waste marble dust can be obtained from marble processing, for information 25% of the mass of marble will be lost in the cutting process obtained from marble companies in Solo Raya, the slump flow test measurement is carried out with reference to according to the rules of SNI 1972-2008 and the workability of self-compacting concrete also meets the required requirements. So it can be concluded that it can be a reference source by utilizing waste in Indonesia, easy to obtain, and effective.
 
 Keywords: Self-compacting concrete, waste marble dust, kaolin

Effect of printed circuit board dust on the workability and mechanical properties of self-compacting concrete: A preliminary study

Electronic waste has had an adverse impact on the environment in this era of fast electronic technology advancement and rapid consumption growth. Therefore, awareness and focus on the sustainable disposal of electronic products should be raised. The objective of this research is to study the feasibility of using the dust from the printed circuit board manufacturing process (PCB dust) as a binder to replace ordinary Portland cement (OPC) for manufacturing of self-compacting concrete (SCC). All of the seven SCC mixtures were obtained by replacing OPC with PCB dust by the volume ratio of 0%, 5%, 10%, 15%, 20%, 25%, and 30% respectively, then the workability and the properties of hardened concrete were investigated. From the experimental results, it can be seen that the workability of SCC tends to decrease with the PCB dust replacing increases, and clear that SCC tends to block during the flow and segregate. The engineering properties of hardened concrete indicates that the efficiency decreases as the amount of PCB dust increases. The highest 28-day compressive strength obtained is about 54 MPa at 5% replacement level and tends to decrease between 11.49% and 57.44% at replacement level between 5% and 30% by volume, when compared to the control mix. However, when SCC is mixed with 20% of PCB dust, it can provide a compressive strength of more than 50 MPa after 180 days. The results of the study point out the possibility of recycling PCB dust as a new filler that can be utilized to reduce the consumption of natural materials.

Performance of Fiber Self Compacting Concrete at High Temperatures

The goal of this study is to assess the fresh and hardened properties of self-compacting concrete (SCC) prepared using locally available materials. This research includes also the impact of polypropylene (PP), steel and hybrid fibers on the same properties. In addition, the mechanical properties of SCC specimens (with and without fibers) at high temperatures, including as compressive, tensile, and flexural strengths, will be determined. Four different SCC mixtures (with and without fibers) are prepared, tested, and assessed in order to attain these goals. The specimens were heated to various temperatures (200, 400, 600, and 800) at a rate of 5 degrees Celsius per minute for each test. The temperature was remained constant at the target temperature for one hour before cooling to ensure a consistent temperature throughout the specimen. According to the test results, all of the mixes have good consistency and workability in terms of filling and passing ability. In addition, the inclusion of fibers lowered the workability of SCC slightly. Also, the compressive, tensile, and flexural strengths improved with increasing temperature up to 200 °C and dropped at temperatures over 200 °C, according to these findings. Within the SCC, the PP fibers lowered and removed the risk of spalling. Concrete mixtures containing steel fibers and hybrid fibers have the finest mechanical characteristics and spalling resistance as temperature rises. Weight losses were lower in SCC mixtures with PP and steel fibers than in those without PP and steel fibers. As the temperature rose, all SCC mixes lost mass and UPV decreased until the samples spalled (as in plain SCC and SCC with steel fibers) or were questionable (as in SCC with PP and SCC with hybrid fibers). Doi: 10.28991/cej-2021-03091779 Full Text: PDF