Workability Tests Research Articles

Effect of superplasticizer types and dosage on the flow characteristics of GGBFS based self-compacting geopolymer concrete

Self-compacting geopolymer concrete (SCGC) is produced from waste materials that act as binders or precursors promoting sustainable concrete. Among all components of the SCGC mix, the superplasticizer dosage primarily controls the workability of concrete along with mechanical strength. An attempt is made in this current study to find the best suitable type of superplasticizer and its dosage through given fresh property investigation. For the accomplishment of the project objective, four types of superplasticizers are considered in the SCGC mix preparation and are polycarboxylate ether-based, modified naphthalene-based, lignosulphonate-based, and mother liquor-type superplasticizers. The superplasticizer dosage considered in each is 4%, 6%, and 8%. In the absence of a suitable design standard SCGC mix designs are prepared and concrete is produced with characterized material components. Twelve M25 SCGC mix designs are prepared with some constant parameters like 12 M concentration of sodium hydroxide, the ratio of sodium silicate to sodium hydroxide as 2.5, and 24% extra water addition. The freshly prepared concrete has undergone various workability tests to examine the filling ability (FA) (slump flow, T50cm slump flow, V-funnel); passing ability (PA) (L-box, J-ring); and segregation resistance (SR) (V-funnel at T5minutes). The 6% naphtha (NP)-based superplasticizer is regarded as the superior superplasticizer from the fresh property consideration in the GGBFS-based SCGC.

Pull-Out behavior and microstructure characteristics of binary blended self-compacting geopolymer concrete subjected to elevated temperature

Geopolymer concrete (GPC) is an emerging green substitute for conventional cement-based concrete. Due to the eco-friendly benefits of GPC, it possesses superior strength properties. Self-compacting concrete (SCC) is a special concrete, it has the tendency to pass and fill congested areas without the help of vibrators. As the Self-compacting based Geopolymer concrete (SCGC) is a sustainable construction material, the knowledge about the thermal performance of SCGC is vital. Therefore, the current work examined the behavior of binary blended SCGC under room temperature and elevated temperatures of 821 °C, 925 °C, 986 °C, and 1029 °C. The investigation's main objectives are to examine the bond performance and microstructure of binary blended SCGC composites subjected to temperature exposure. Three types of mixes are considered in the investigation, namely FA (100% Fly Ash (FA)), F-G (50% Fly Ash (FA) and 50% Ground Granulated Blast Furnace Slag (GGBS)), and F-M (50% Fly Ash (FA) and 50% Metakaolin (MK)). The workability tests, such as the Flow test, T500 test, V-funnel test, and J-ring tests, were carried out in line with EFNARC guidelines to examine the rheological properties of SCGC. The SCGC composites were subjected to temperature exposure following ISO 834 standard fire curve. The Pull-Out (PO) test was carried out to investigate the Bond stress (BS) of the heated and unheated SCGC composites. The Bond stress of the SCGC composites decreases with an increase in temperature exposure. Test results show that the F-G mix possesses higher BS for unheated specimens, followed by F-M and FA mix. When exposed to elevated temperature, the SCGC composite mix F-G and F-M exhibit higher strength loss (%) than the FA mix. A relationship has been established between the compressive and bond stress of SCGC.

Experimental Study of Partial Replacement of Cement by Pozzolanic Materials

Abstract: Pozzolanic materials such as ground granulated blast furnace slag i.e. GGBS, Solid waste ash, iron husk, silica fumes, iron slag etc are the most common industrial by-products generated. Some of these waste material shows similar properties/elements as that of cement. So these waste materials can be used in concrete as a partial replacement of cement. So, in this study, the attempt to partially replace the cement by GGBS and solid waste ash is carried out. Here, the cement is partially replaced by different percentage of GGBS (10%, 15%, 20% and 25%) and same for solid waste ash (4%, 6%, 8% and 10%) and the concrete mixes were made along with the control mix concrete. Workability test, compressive strength test etc. are performed on the specimen. From the results, it is observed that the workability of the concrete gets affected due to replacement by GGBS and solid waste ash. The compressive strength of GGBS concrete increases till 20% replacement whereas the compressive strength of solid waste ash concrete increase till 4% replacement. Further that it shows decrease in value. It is concluded that the optimum percentage for partial replacement of cement for GGBS is 20% and for solid waste ash is 4%.

Laboratory investigations of the effects of asphalt mortar and its viscoelasticity on the workability of asphalt mixtures

In order to understand the flow characteristics of asphalt mixture in the composition of materials, the influence of the viscoelastic properties of asphalt mortar on asphalt mixture workability was investigated. In this study, an asphalt mixture workability test device was developed and the corresponding evaluation index was proposed. Analysis of the basic and rheological properties of asphalt mortar for different filler-asphalt ratios and asphalt compositions, and evaluated the corresponding asphalt mixture workability. Finally, the distribution uniformities of asphalt mortar, aggregate and pore structure in compacted asphalt mixture were analyzed according to digital image processing techniques. The obtained experimental results showed that asphalt mixture workability was closely related to asphalt mortar viscoelastic properties. Also, rheological indices such as viscosity, complex shear modulus G*, phase angle δ and rutting factor G*/sinδ of asphalt mortar were to be highly correlated with workability index. As the viscosity of asphalt mortar was increased, workability index was also enhanced. In addition, lower asphalt mixture workability resulted in poorer uniformity of material distribution.

Research on evaluation method of asphalt mixture workability based on minimum mixing energy consumption

The workability evaluation of hot mix asphalt mixtures is of particular importance for the uniformity analysis of asphalt mixtures and influence of later asphalt pavement properties. Currently, workability tests and evaluation systems for hot mix asphalt mixtures are not perfect. In this study, we have developed a testing device, proposed an evaluation index, and established an evaluation system for asphalt mixture workability. The compaction degree, asphalt distribution uniformity evaluation index (ADU), aggregate distribution uniformity evaluation index (HA), and coated uniformity of asphalt film evaluation index (CUAF) were measured to verify the workability evaluation index of asphalt mixture. Test results demonstrated that the newly developed asphalt mixture workability testing device and workability evaluation index accurately quantified the shift law of asphalt mixture workability during mixing process. The variation of the workability law was affected by asphalt type, mixture type, and mixing temperature. Compactness, ADU, HA and CUAF were closely correlated with workability evaluation indexes, and R2 values were 0.73, 0.77, 0.94 and 0.8, respectively. Validation results of the workability evaluation index of compactness, ADU, HA, and CUAF showed that the newly proposed workability evaluation index for asphalt mixture was feasible and effective.

Effect of Bamboo Leaf Ash on The Properties of Geopolymer Concrete at Ambient Curing Temperature

As a result of the growing environmental concerns in the cement industry and the rising cost of building materials, alternative cement technologies have become an area of increasing interest. In this study, geopolymer concrete containing fly ash class F and bamboo leaf ash was chosen as a cement substitute in concrete manufacturing. This research was an experimental study evaluating the effect of bamboo leaf ash (BLA) on geopolymer concrete by addition as a partial replacement of fly ash. The test samples were 100 x 100 x 100 mm cubes and 300 x 150 mm cylinders at the ambient curing temperature. The design mix of C25 was used for this study. This research aimed to explore the suitability of the use of bamboo leaf ash as a mixing material in geopolymer concrete in more environmentally friendly industries. The properties that were investigated in this study are the basic aggregate tests, XRF analyses of BLA and fly ash, and workability tests by evaluating slump and compaction factor tests. In addition, compressive strength and splitting tensile strength of 28, 56, and 90 days. Therefore, in this study, various levels of bamboo leaf ash were utilized, including 0%, 5%, 10%, 15%, and 20% BLA. The alkaline liquid-to-binder ratio for all mixes was constant at 0.6, while the Na2SiO3 to NaOH ratio was 2.5. The test results of the workability show that the increased amount of bamboo leaf ash gradually reduces the alkaline liquid. The result of compressive and splitting tensile showed that fly ash substitutes that contained 5% and 10% of the bamboo leaf had higher strengths of about 38.7 MPa, 40.8 MPa, 4 MPa, and 4.22 MPa, respectively than other mixtures. Therefore, bamboo leaf ash can be one of the constituent materials used to improve the mechanical properties of geopolymer concrete

Mechanical and bond behaviour of high volume Ultrafine-slag blended fly ash based alkali activated concrete

The development of Geopolymer concrete (GPC) mixes by employing large volume of ultrafine ground granulated blast furnace slag (UBFS) blended with Fly ash (FA) and activated by sodium hydroxide (SH) has been presented in this study. Several GPC mixes has been prepared to investigate the effect of varying alkali content, fine aggregate to total aggregate ratio (s/a) and molar concentration (M) of alkali activator on the fresh and hardened characteristics, including the bond strength with Portland cement concrete (PCC). The properties of the GPC mixes are assessed by workability test, compressive strength test, split tensile strength test and slant shear test, including the microstructure through FESEM (Field Emission Scan Electron Microscopy) and X-ray diffraction (XRD). The test result shows that s/a ratio is a crucial factor in controlling segregation and bleeding in GPC. However, an ideal GPC mix with s/a ratio 0.41 provides a better packing resulting in improved mechanical properties. Application of high volume UBFS in the GPC exhibits better reaction products as shown by the microstructure at a relatively lower alkali concentration which ultimately leads to higher strength. Superior bond strength is achieved between the GPC and old PCC substrate; however, the molarity of SH significantly affects the adhesion property of GPC.

Impacts of Rejuvenator Pretreatment and Marination on Quality Characteristics of Reclaimed Asphalt Pavement

To mitigate the potential cracking performance issues of high reclaimed asphalt pavement (RAP) asphalt mixtures, rejuvenators can be added to restore the rheological and chemical properties of the RAP binder. Traditionally, rejuvenators are pre-blended into the virgin binder before mixing, which may limit the direct interaction between the rejuvenator and RAP. Therefore, alternative methods of adding rejuvenators by pretreating RAP with appropriate marination before mixing with virgin materials should be considered to potentially enhance the rejuvenating effectiveness of these products. In this study, three RAP pretreatment methods (spray-on, emulsified, and foamed rejuvenators) were explored. The effects of each pretreatment method on RAP quality properties were characterized through workability evaluation based on the Dongre Workability Test (DWT), durability assessment based on the Cantabro test, and grayscale image analysis. From these results, the most effective pretreatment method was selected to evaluate the impact of marination on RAP quality via the same characterization techniques. Four marination conditions were evaluated, including 3 and 7 days at 25°C, and 1.5 and 3 h at 135°C. Furthermore, asphalt binders extracted from untreated and pretreated RAP samples at selected marination conditions were tested for rheological and chemical characterization. Test results indicated that RAP quality significantly improved with pretreatment with the rejuvenator, but the degree of improvement varied depending on the rejuvenator dosage and application method, among other factors. Marination also affected the RAP binder properties but did not significantly improve the overall quality characteristics of the RAP in relation to DWT, Cantabro, and grayscale image analysis.

Exploring the performance of Fe-Al rich sand in fly ash-based cementitious system in the context of a sustainable built environment

This research seeks to manufacture concrete by replacing fine aggregates in concrete with Fe-Al rich sand obtained from laterite scraps (mine waste) and fly ash-based cement. To reduce the colossal dumping of laterite scraps and curtail the utilisation of virgin aggregates, this study was done to utilise the laterite scraps effectively in concrete. In this study, laterite scraps were collected as rocks and processed into Fe-Al rich fine aggregates. The processed Fe-Al rich sand was employed in various amounts and substituted as fine aggregates ranging from 0 % to 100 % at 25 % intervals. The morphological properties of raw materials, clay content percentage, workability, strength, microstructure, and phase evolution studies on Fe-Al rich sand-based concrete were investigated. The workability tests such as slump, compaction factor, Vee Bee consistency, and flow table indicated that the workability values of all the Fe-Al rich sand-based mixes were lesser than the control mix. The compressive strength, splitting tensile strength, and flexural strength values of Fe-Al rich sand-based concrete were reported to be greater than those of control concrete, but up to 50 % level of replacement, they demonstrated higher values. Furthermore, the decline in strength above 50 % was evaluated in comparison to that of conventional specimens. Microstructure and phase evolution studies on Fe-Al rich sand-based concrete revealed that the strength of Fe-Al rich sand-based concrete mixes changed as hydration products formed. This work further iterates that replacing natural fine aggregates with Fe-Al rich sand as a partial alternative in concrete has a significant ecological and long-term benefits.

Study on Durability Characteristic Strength of Recycled Waste Concrete as Fine Aggregates in Self-Compacting Concrete

Abstract: In developing nations, with the raising overpopulation, both economy and pollution free environment in construction industry are of principal importance in order to meet the undeniable human needs of multifarious forms. Thus, use of waste aggregates in the manufacturing is of new type of concrete, which plays a critical role in the construction industry, for fulfilling the demand of aggregates. Most of the waste materials are arising from industrial waste and demolishing waste. Hence, recycling, reuse and exchange of this waste appears to be an effective solution and most appropriate decision. In the current research work desirable characteristics of recycled aggregate concrete were considered. These experiments were conducted for different ages of concrete such as 7 and 28 days to assess the split tensile strength. The workability properties of mix are evaluated by workability tests are flow test. It addresses experiment on different mixes of self- compacting concrete. One with fresh coarse and fine aggregates, while the others with restoration of 15%, 30%, 45%, 60%, 75%, 90% and 100% recycled fine aggregates. The design mix proportion in M25 with the proportionate of 1:1:2 for self-compacting concrete is taken.

Influence of asphalt mixture workability on the distribution uniformity of asphalt, aggregate particles and asphalt film during mixing process

Due to the homogenization of asphalt mixture, the service life and road performance of asphalt pavements are found to be seriously affected by the segregation of the asphalt mixture. The distribution mechanism of the asphalt on the aggregate as well as its distribution uniformity are also considered as major issues in the construction of asphalt mixtures during the mixing process. Accordingly, the present study aims at investigating the distribution uniformity of asphalt, aggregate particles, and asphalt film during the mixing process of asphalt mixture. Furthermore, the study intends to explore the effect of workability on the mixing uniformity of the mixture. To achieve these goals, a workability evaluation method was presented for the assessment of the asphalt mixture. In addition, using combustion furnace, scanning electron microscope (SEM), standard sieve, etc., the mixing uniformity was analyzed by evaluating the asphalt distribution uniformity (ADU), homogeneity of aggregate (HA), and coating uniformity of asphalt film (CUAF). Also, applying linear correlation, the correlation between workability and ADU, HA, and CUAF was determined. The obtained results corroborated the applicability of the proposed asphalt mixture, workability test equipment and evaluation metrics. The distribution of the asphalt and aggregate in the upper and the lower layers of the mixing pot was also found to be more severe than that of the different directions of the pot. Moreover, the existence of more coarse aggregates in the asphalt mixture was shown to result in a greater degree of aggregate dispersion. The homogeneity of the asphalt film was also observed to be greatly affected by the mixing temperature. Finally, the mixture’s workability was found to have a significant impact on the ADU, HA, and CUAF of the mixture.

Strength and Workability of Concrete with Inclusion of Fly Ash, Quarry Dust and a Generic Naphthalene-based Super Plasticizer

Poor strength and workability often result in low quality concrete that can cause structural failures. This research work was conducted to improve the strength and workability of concrete at reduced amount of water due to the addition of super plasticizer by replacing partially the concrete materials: cement, with fly ash at 0%, 5%, 10% and 15%; fine aggregate, with quarry dust at 0% and 15%; and the addition of sulphonated Naphthalene Formaldehyde Condensate (SNFC) super plasticizer at 0% and 0.6% by weight of cement content reducing the amount of water to 0.45 w/c from the conventional 0.6 and 0.55 w/c ratio. Concrete cube specimens were prepared with these inclusions using grade M20 concrete and nominal mix proportion of 1:2:4. Sieve analysis test, specific gravity test, fineness test were carried out on the concrete materials, workability test was carried out on each concrete specimen, a compressive strength test and weight density test was done at 7days and 28days curing. The compressive strength of concrete made with fly ash, quarry dust and SNFC at 28days ranges from 19.58N/mm2 to 30.23N/mm2. These results were higher compared to those of conventional concrete. A combination of fly ash, quarry dust and SNFC was then recommended for solving problems of low-strength concrete.

In-pipe hydropower vertical axis parallel turbines prototype: performance and workability testing

ABSTRACT An improvised version of a vertical axis twin turbine in-pipe hydropower prototype, with bigger power generation (PG) channels and turbines as compared to the previous one was developed and designated as P40. The P40 was fabricated mainly using mild steel. This study aims to evaluate the flow properties, power generation performance, and workability of the P40. At the maximum flow rate of 0.076 m3/s, each of the PG channels at both sides of the P40 allowed about 13% of the water to flow through them and the P40 absorbed 34.4% of the 1.25 bar stagnation pressure of the flow. Both turbines showed almost identical performance, generating a total mechanical power up to 0.608 kW at the maximum flow rate. Overall, a turbine efficiency of more than 70% was obtained at respective flow rate conditions and the highest was 84.7%. All the valves at the inlets and outlets of the PG channels functioned perfectly not to let water flow through them to allow for maintenance work of the turbines’ system when necessary. Overall, the P40 performed effectively as a device that allowed most water to flow uninterruptedly, while simultaneously generating power. Based on the water splash effect in the turbine casing, further study is recommended to increase turbine efficiency by improvising the prototype design.

Evaluation of the Rheological and Durability Performance of Sustainable Self-Compacting Concrete

Self-Compacting Concrete (SCC) is a special concrete that can flow easily across congested reinforcements. Also, it is easy to work with and does not segregate. The present investigation aims at the design and development of sustainable SCC with the employment of industrial by-products such as Fly Ash (FA), Ground Granulated Blast Furnace Slag (GGBFS), and Expanded Perlite Aggregate (EPA). Four SCC mixes were developed to attain a target strength of 30 MPa. Workability tests (slump flow, J-ring, and V-funnel tests) were performed following the EFNARC guidelines to ensure fresh SCC properties. Detailed experiments were conducted to evaluate the durability characteristics of the developed SCC, such as water absorption, sorptivity, acid attacks (sulphuric, nitric, sulphate, and chloride), the Rapid Chloride Penetration Test (RCPT), and finally, the elevated temperature test. Weight loss, strength loss, and physical observations of the acid and temperature effects of SCC mixes were evaluated. Also, the study focuses on the cost and sustainable index of SCC mixes and compares them with OPC mixes. From the experimental data analysis, it was observed that the developed SCC showed excellent physical and mechanical properties with a considerable reduction in cement content. SCC specimens with FA and EPA exhibit excellent acid and temperature resistance. Following the sustainable analysis, it was noted that SCC mixes reduce about 15–17.2% of carbon emissions compared to the OPC mix.

Experimental Behavior of Self Compacting Concrete Using Red Mud

The primary purpose is to explore the effect of neutralised red mud on the properties of self-compacting concrete. Furthermore, it aims to analyze the impact of replacing cement with red mud and other chemicals used in concrete by comparing the strength attributes of self-compacting concrete made with red mud to those of regular self-compacting concrete and conventional concrete strength. The qualities are thus determined using the workability test. Concrete's durability strength is increased by substituting a portion of the fine aggregate with fly ash. In underdeveloped countries like as India, the major goal is to reduce construction costs. To attain this goal, significant efforts are being made to maximize the utilization of trash and byproducts. In light of this, an investigation on SCC (self-compacting concrete) is being done, cementitious material is partially replaced with red mud and 2.5% of the sand was replaced with iron tailings. In our project, we used M30 grade concrete and substituted the cementitious ingredient in the mixture with Red mud.

Exploration of Curing Characteristics of Epoxy-Modified Asphalt

A study was conducted on epoxy-modified asphalt (EMA) diluted with two binders of a different chemical structure, to understand the effect of curing rates and long-term postcuring characteristics. Dynamic shear rheometer test results did not show a clear trend of curing time and dosage percentage impact for the two base binders; parallel-plate geometry may not be well-suited to study EMA because of the thermosetting properties of curing. The asphalt binder test (ABT) method was used to assess the effect on rheology of short-term and long-term curing. Analysis of the ABT data to date suggests that the binder source has a notable effect on the composite properties. The impact of long-term storage was also found to be dependent on the asphalt binder used. Findings from this study were also applied to two field binders; one was modified using styrene-butadiene-styrene polymer, and the other contained epoxy. Curing times were determined using the ABT test. The Dongre Workability Test (DWT) was also conducted on open-graded friction course mixes and the mix curing times were found to be significantly higher than those determined on the binders. A method based on DWT data to determine a “workability window” was also explored. The Strategic Highway Research Program (SHRP) sol-type binder AAG-2 was found to exhibit little to no reactivity with the epoxy modifier used in this study. The SHRP gel-type binder AAD-2, however, was found to be highly reactive. The short-term curing temperature was found to affect the rate of curing for base binder AAD-2. The curing rate was found to be highest at 165°C followed by 120°C, and the rate was at its slowest at 25°C. AAG-2 did not show any onset of curing at either temperature.

Izdržljivost na pritisak i uticaj na propustljivost tretiranih otvora bušotina kod delimične zamene cementa u proizvodnji betona

This study examines the compressive strengths and leachability effects of treated drill cuttings as a partial replacement of cement in concrete production. Workability tests on various water-binder ratios (w/b) on the fresh concrete showed that an optimum w/b of 0.5 was adequate for the concrete to be workable. Replacement levels of 0, 5, 10, 15, 20, and 25% were used to produce cement-drill cuttings concrete at a 1:1.5:3 mix ratio. The blended concrete gave a compressive strength in the range of 26.20N/mm 2 for 5% to 22.46N/mm 2 for 20% replacement levels at 28 days curing time, more than the minimum compressive strength of 20N/mm 2 and 25N/mm 2 specified for concrete strength class C/20 and C/25, respectively. The strength activity index of 90.56, 98.76, 89.05, 98.05, and 77.64% for 5, 10, 15, and 20% replacement levels at 28 days of curing time was obtained surpassing the minimum 75% specified for normal concrete by the code. The wet/dry durability effects of the blended concrete at any replacement level passed the structural integrity with less than 5% of the structural integrity of the material lost. The chloride and total polycyclic aromatic hydrocarbons (TPAHs) leachability effects both met the DPRs target values for reusable materials. The study has shown that drill cuttings have a good pozzolanic effect on concrete, especially when activated at the temperature of 500oC for 180 minutes. It also shows that treated drill cuttings could replace cement up to 20% by weight to produce concrete of adequate strength using a w/b ratio of 0.5 and mix ratios of 1:1.5:3. The study has also shown that treated drill cuttings replaced with cement to produce concrete which is durable to both wet/dry and leaching effects of chlorides and TPAHs to the environment.

Cementitious nanocomposites engineered with high-oxidized graphene oxide: Spotting the nano to macro correlation

There has been increasing interest in using nanosized fillers in cement-based construction materials to upgrade mechanical properties, durability, and multi-functionality. In this context, graphene oxide (GO) is proved to be an effective candidate, and its interaction with cement can lead to remarkable enhancement in its macro-properties. To guarantee reproducibility and to maximize environmental and health safety, a GO water suspension ( GONan, Nanesa, Italy ) was selected from the market-available products. A complete morphological, microstructural and chemical characterization was performed by Atomic Force Microscopy (AFM), X-ray Photoelectron Spectroscopy (XPS), Raman Spectroscopy, Infra-Red Spectroscopy (FTIR-ATR), X-ray Diffraction (XRD), and Thermogravimetric Analysis. The aggregation test of GONan in saturated Ca(OH) 2 water solution was also performed, and results were obtained by UV-VIS spectroscopy and Scanning Electron Microscopy (SEM). Different dosages (0.01%, 0.1%, and 0.2% by weight of cement) of GONan were added to a commercial M5 mortar. Fresh properties were determined by rheology measurements and flowability and workability tests. Samples were hardened in water at room temperature (RT) for 7, 14, and 28 days. The compressive and bending strength of all samples were evaluated following the standards. The microstructural features of nanocomposites hardened at 28 days were investigated by SEM. Results clearly evidenced that the extra-low GONan dosage (0.01%) was the most promising formulation. Despite the worsening of fresh properties (i.e., increase of plastic viscosity and decrease of flowability and workability by 150%, 50%, and 100%, respectively, compared to the control sample), the mechanical properties of such an extra-low dosage nanocomposite at 14 days showed a notable increase of 20% and 40% for bending and compressive strength, respectively.

Effect of Recycled Aggregate Concrete and Steel Fibers on the Fresh Properties of Self-Compacting Concrete

Globally, the amount of solid waste is constantly increasing, and its disposal is one of the critical issues in recent research studies. Concrete waste includes the rubble of demolished buildings, whether old buildings or those that have been subjected to earthquakes, etc. This research project aims to improve sustainability in the construction industry by recycling and reusing coarse aggregate that was previously used in concrete buildings. The objective is to utilize this recycled material to produce self-compacting concrete (SCC) and assess its performance in its fresh state. By finding new ways to repurpose materials that would otherwise go to waste, this research contributes to developing environmentally friendly practices and reducing the industry's carbon footprint. Furthermore, evaluating the performance of the recycled coarse aggregate in SCC will provide insights into its potential for future use in construction projects, which could ultimately lead to cost savings and improved efficiency in the industry. Recycled coarse aggregate (RCA) was used as a substitute for the natural coarse aggregate (NCA) with volume ratios of 0, 25, 50, 75, and 100%, and steel fibers (SF) were added to the concrete with different volumes ratios (0, 0.5, and 1 %). Workability tests such as slump flow, V-funnel, and L-box tests were carried out for the mixtures in their fresh state. In general, the results of the experimental work showed that the fresh properties indicated that almost all SCC mixtures were within the specified range, as stated in EFNARC requirements.

Behavior of self-compacting concrete by the addition of recycled aggregates and nano-silica

The construction industry is growing rapidly all over the world and busy in inventing the new construction materials. The existing construction materials which are used for constructions from past decades were accumulating on the land as a waste, due to lack of reutilizing the used materials. In this experimental work, efforts were made to re-utilize the recycled aggregates which are also called demolition waste aggregates. The current study is divided into two stages. The first stage of work examines the influence of recycled aggregates on the characteristics of self-compacting concrete (SCC). The second stage includes the substitution of cement by nano silica and replacement of normal aggregates by recycled aggregates (RA) in the SCC mix. In this study, natural aggregates are replaced by 10%, 20%, 35% and 50% with recycled aggregates by the weight of total aggregates. Nano silica (NS) is used in this study, which replaces the 0.5% and 1% by weight of cement for each partial replacement level of recycled aggregates. The workability tests were performed on prepared SCC mix. The workability properties were satisfying the requirements of SCC. The compressive, split tensile and flexural strength tests were conducted on hardened concrete. The microstructural configuration of SCC containing with and without RA & NS mixtures were examined using a scanning electronic microscope (SEM). The RCPT test was conducted to understand the durability of the SCC. The outcomes of mechanical properties were optimum at 35% replacement of RA in first stage of work. Similarly, mechanical properties were optimum at 1% of NS and 35% of RA in second stage of work. The SEM analysis reveals the micro structure of mixes, the nano silica replaced concrete mix exhibit the lesser voids compared to RA replaced concrete. It results shows that voids were filled with nano particles and enhances the performance of SCC mix.