Exploring the potential of arecanut fibers and fly ash in enhancing the performance of self-compacting concrete

Self-compacting concrete (SCC) is an innovative material for construction that offers excellent workability and flowability while achieving effective and uniform compaction without the need for external vibration. Using an experimental approach, this study investigates the effect of incorporating arecanut fibers on the performance of self-compacting concrete (SCC). The focus is on optimizing the fiber content for improved concrete characteristics. The study examines three different fiber lengths (8 mm, 10 mm, and 12 mm) and three volume fractions (1%, 2%, and 3%) while partially replacing 30% of the cement by weight with fly ash. Tests on the workability of the SCC mixes revealed favorable characteristics: slump flow between 650 and 750 mm, T 500 slump flow time of 2–5 s, V-funnel time of 5–10 s, L-box ratio of 0.8–1.0, and J-ring values within 0–10 mm as recommended by EFNARC guidelines. Furthermore, incorporating 30% fly ash and arecanut fibers significantly enhanced the hardened properties of the SCC, particularly its compressive strength. A concrete mix containing 2% of 10-mm long arecanut fibers achieved a compressive strength of 40.26 MPa, which is about 15.14% increase compared to the reference strength of 35 MPa. Similarly, using a 1% volume fraction of 12 mm arecanut fibers increased the split tensile strength by 14.04% and the flexural strength by 35.87% compared to the control mix. Fly ash and arecanut fibers enhance the durability of SCC by reducing Coulomb charges and improving resistance to chloride penetration. However, the increased water absorption rate of the fibers can lead to increased overall water absorption in the concrete. Microstructural analysis (SEM) revealed improved bonding and reduced voids, further supporting enhanced durability. Additionally, EDX analysis confirmed the presence of various elements from cement and fly ash, providing valuable data for evaluating the long-term performance of these SCC mixes.


Introduction
Recent advancements in concrete technology, particularly self-compacting concrete (SCC), have significantly transformed construction methods.SCC eliminates the need for manual compaction, boosting productivity and promoting environmental sustainability.This innovative material boasts exceptional flowability, achieved through advanced admixtures and optimized particle packing.This revolutionizes concrete placement, making SCC suitable for a diverse range of applications, including intricate structures, prefabricated elements, and artistic designs.In modern construction, SCC fosters both superior quality and expedited construction times [1][2][3].
Reducing the amount of cement, the most expensive component in concrete, renders financial cost-cutting.Mineral admixtures like fly ash, blast furnace slag, and limestone powder could be substituted as supplementary cementitious material while optimizing particle arrangement.This does not only lower costs but also improves concrete's density, reducing permeability and extending its lifespan.Furthermore, using industrial wastes like fly ash in self-compacting concrete enhances workability, reduces pollution, and contributes to sustainability goals [4].When fly ash is added to SCC, it enhances both workability and cohesiveness.Additionally, fly ash undergoes pozzolanic reactions that increase the strength and durability of the concrete.This can lead to a significant increase in compressive strength, up to 38% with a 30% replacement of cement.These improvements make SCC a versatile and environmentally friendly option for various construction projects [4][5][6][7][8][9][10].
Inclusion of either natural or synthetic fibers significantly improves self-compacting concrete's flexural strength, durability, and crack resistance, which results in improved structural integrity and a longer lifespan under normal operating conditions.Additionally, the SCC with fibers excel in various construction applications because they optimize the concrete's rheological properties, allowing for better flow and improved stability during placement [11].One of the key advantages of SCC is its excellent workability.Unlike traditional concrete, SCC eliminates the need for vibration during compaction.To achieve this superior workability, SCC uses a finer maximum aggregate size compared to traditional mixes.This necessitates a higher proportion of fine aggregate in the mix design.Additionally, superplasticizer additives are crucial to ensure the SCC flows easily and fills the mold without segregation.The addition of fibers to concrete, especially SCC, improves ductility under a range of stresses and lessens the likelihood of brittle failure.These days, fiber-reinforced concrete is frequently used in infrastructure projects like tunnels, bridges, and road paving [12,13].
Overuse of natural resources results in scarcity of materials in the environment, global warming, and resource depletion.A number of research have focused on the sustainable use of alternative materials and natural resources, including fly ash (FA), rice husk ash (RHA), silica fume (SF), ground granulated blast furnace slag (GGBS), and metakaolin, to address these issues.The utilization of artificial and natural fibers (such as carbon, steel, polypropylene, and glass fibers) in conjunction with these mineral admixtures have been researched in the literature.Researchers have investigated how adding both fibers and coarse fly ash affects self-compacting concrete (SCC) [5].Dinakar et al. [7] compared self-compacting concrete (SCC) with and without fly ash to see how fly ash affects durability properties.They made SCC mixes with various fly ash contents (0 to 85%) and compared them to regular vibrated concrete of similar strength.While SCC with fly ash had slightly larger pores and absorbed more water, it performed better in acid resistance and chloride penetration tests compared to regular concrete.Sandhu and Siddique [6] review research on how Rice husk ash (RHA) impacts the properties of self-compacting concrete (SCC).They found that using 10-15% RHA can improve SCC's strength and durability.Siddique [8] studied self-compacting concrete (SCC) with varying amounts of class F fly ash (15 to 35%).Tests include the concrete's workability, strength, and durability properties.The SCC mixes achieved good compressive strength (30)(31)(32)(33)(34)(35) but showed increased carbonation depth and lower chloride resistance with more fly ash.A mix containing 30% fly ash had a 40% higher compressive strength than the control mix.
Several research studies have investigated the impact of incorporating steel fibers into self-compacting concrete, focusing on how they improve the concrete's impact resistance and mechanical properties [12,[14][15][16][17][18].Mastali and Dalvand [14] examined how replacing cement with silica fume and adding recycled steel fibers affects the strength and impact resistance of SCC.They casted 144 concrete samples with different amounts of steel fibers (0.25%, 0.5%, and 0.75%) and tested their compressive, splitting tensile, and flexural strengths.They found that both silica fume and steel fibers improved the strength and impact resistance of SCC.Sharma and Sheikh [15] studied how different fiber percentages affect the mechanical and rheological properties of fiber-reinforced self-compacting concrete (FR-SCC).They used two types of fibers (steel and coir) in different proportions (0.5%, 1.0%, 1.5%, 2.0%) and tested the concrete's mechanical properties.Researchers observed that both types of fibers improved the concrete's strength, with the highest strength achieved at 2% fiber content.SCC with steel fibers (higher aspect ratios) generally led to lower workability but did not significantly affect compressive strength.They also improved flexural strength, toughness, splitting tensile strength, and impact resistance, while reducing permeability [16].Likewise, metalized plastic waste (MPW) fibers improved the concrete's resistance to cracking and tearing.Additionally, the SCC with MPW fibers showed larger deformations under axial compression compared to the control concrete [19].
Natural fibers offer a promising approach to enhancing the performance and sustainability of SCC [20,21].Prasad et al. [22] justify the use of coconut fibers in SCC for structures in seismic zones by demonstrating their improved performance under cyclic loading compared to plain SCC.Divakar et al. [11] investigated how adding arecanut fibers affects the mechanical properties of self-compacting concrete, specifically focusing on compressive and flexural strengths.They added varying amounts of fibers, from 0 to 3% in increments of 0.5%.The study concludes that adding 1.5% or 2% of arecanut fibers to SCC offers improved flexural strength without a significant decrease in compressive strength.The primary goal of using fly ash with cement is to increase the SCC's compressive strength; however, doing so may reduce the material's split tensile and flexural strengths when used at higher proportions.Using arecanut fibers along with fly ash may improve all the mechanical properties of SCC.Hence, this study aims to experimentally evaluate the performance of SCC mix that offers the combined benefits of fly ash and arecanut fibers.Identify the optimal proportions of arecanut fiber to achieve a balanced improvement in all key mechanical properties of SCC.

Cement
Ordinary Portland cement (OPC) was used in this study.The physical properties of cement are shown in Table 1.Cement was tested as per the Indian standard code IS: 4031-1988 (Parts IV & V) [23,24].

Fly ash
Fly ash, a byproduct of burning coal, is a fine dust that is rich in silicates and aluminates.It is commonly added to concrete as an additional cementitious ingredient.It does not only increase long-term strength but also makes the material more workable, lowers the heat of hydration, and supports sustainability by recycling industrial waste.Table 2 presents the chemical properties of fly ash used in this study.

Arecanut fibers
This research used arecanut fibers.To improve their workability in the SCC mix, the fibers underwent a two-step treatment.Step 1: Drying and soaking.First, the fibers were submerged in water for 24 h and then oven-dried at 70 °C.This initial process likely removes any surface impurities and prepares the fibers for the next step.Step 2: Soaking in NaOH solution and drying.Afterward, the fibers were soaked in a 6% sodium hydroxide (NaOH) solution for 24 h.Soaking in NaOH can make the fibers more pliable and easier to handle during mixing.Finally, the fibers were rinsed in clean water multiple times and allowed to sun dry. Figure 1 shows the arecanut fibers before this treatment.The fibers were chopped into three different lengths: 8 mm, 10 mm, and 12 mm.The  SCC mix incorporated the fibers in a saturated surface dry (SSD) condition.Table 3 presents the physical properties of the untreated arecanut fibers.

Aggregates
Manufactured sand (M-sand) was used as fine aggregate in this experimental study.The M-sand particle size distribution met the requirements for zone II as specified in the IS 383-2016 [25] standard.To ensure its suitability, the properties of this M-sand were thoroughly examined, and the results are documented in Table 4. Crushed natural granite stones of 20 mm and 12 mm downsize were used as coarse aggregate.The physical   properties of coarse aggregate were examined in conformity with IS 2386-1968 [26] guidelines, and the results are presented in Table 5.

Chemical admixture
Chemical admixtures are integral to optimizing concrete performance, offering multifaceted benefits.They have the capacity to lower water content while preserving workability, regulate setting times to enhance construction flexibility, bolster durability against environmental factors, and tailor concrete strength to precise project specifications.In this experimental investigation, Conplast SP430 DIS was used as a chemical admixture supplied by FOSROC chemicals.The properties of this admixture are listed in Table 6.

Methodology
This research follows a well-defined, step-by-step approach to investigate the properties of self-compacting concrete (SCC) in both its fresh and hardened states.Figure 2 visually summarizes the workflow of this study.

• Material collection and preparation:
❖ Fly ash and arecanut fibers were obtained.❖ Arecanut fibers were optionally treated with a sodium hydroxide (NaOH) solution.
❖ Fibers were cut into three different lengths: 8 mm, 10 mm, and 12 mm.❖ Basic quality tests were performed on fly ash, coarse aggregate, fine aggregate, and cement to ensure compatibility and high quality.
• Mix design and testing: ❖ A mix design was established to determine the optimal proportions of all materials for the SCC.• Fresh state characterization: ❖ Workability tests, such as slump flow, J-ring, V-funnel, and L-box tests, were conducted on the SCC mixes to assess their flowability.
• Sample preparation and curing: ❖ Cubes, cylinders, beams, and discs were cast using the designed SCC mixes following IS guidelines [27].❖ After casting, the specimens were removed from their molds and cured for 28 days.

Mix design
This research includes a self-compacting concrete (SCC) mix design that meets the requirements of Indian standard codes IS 10262-2019 [28] and IS 456-2000 [29] for M35 grade concrete.Achieving this M35 grade requires a careful balance between workability (how easily the concrete flows) and strength.This study focused on using fly ash as a partial replacement for cement and adding areca nut fibers for reinforcement.The mix typically includes water, cement, coarse and fine aggregates (gravel, M-sand), superplasticizers (chemical admixtures to improve flow), fly ash (30% by weight of cement) to enhance long-term strength, and arecanut fibers (different lengths: 8 mm, 10 mm, 12 mm) in varying amounts (1%, 2%, 3% of total volume) to improve toughness.To finetune the mix, several trial batches were coordinated.The ultimate goal was to create the SCC mixes that achieves M35 grade strength while still maintaining good flowability.
The specific proportions used in each mix design can be found in Table 7.
The self-compacting concrete (SCC) mixture was prepared in a 300-kg electric-powered concrete mixer.For accurate proportions, all ingredients were precisely measured: fly ash, cement, fibers, fine and coarse aggregates, water, and super-plasticizer.To ensure even distribution of fly ash throughout the SCC mix, it was added first.Next, all dry ingredients (except water and super-plasticizer) were mixed in the drum.Finally, the measured water and chemical admixtures were added to the dry mix.Careful and consistent mixing throughout the process ensured a fully integrated and homogenous SCC mixture.

Workability tests on SCC
Following the mixing of the materials, a series of tests are performed to assess its flowability, a crucial property for SCC.Four essential tests determine SCC's flowability, which is mainly influenced by its viscosity.Two common methods to evaluate SCC flow on flat surfaces are the slump flow and the T 500mm flow tests.J-ring test is employed to assess how easily SCC flows around obstacles like rebar cages.The spread of the concrete inside and outside the J-ring is measured.The V-funnel test measures the time it takes for concrete to flow through a V-shaped funnel and lastly the L-box test evaluates SCC's ability to flow into tight spaces.Standardized guidelines for equipment and testing procedures are recommended by EFNARC [30].After completing these tests, the fresh SCC will be ready for casting.

Tests on hardened SCC
After 28 days of curing, compressive and splitting tensile strength tests were conducted on SCC specimens following standard procedures: ASTM C 39 [31] for compressive strength test and ASTM C 496 [32] for splitting tensile strength test.Cube specimens (150 × 150 × 150 mm) were used for compression testing, and cylindrical specimens (150 mm diameter × 300 mm tall) were used for splitting tensile strength testing.Flexural strength was determined using a third-point loading method on beam specimens measuring 500 × 100 × 100 mm following ASTM C 78 [33] guidelines.Discs with a diameter of 100 mm and thickness of 50 mm were prepared to evaluate chloride penetration resistance and water absorption (sorptivity).Rapid chloride penetration test was conducted according to ASTM C 1202 [34], and sorptivity test followed ASTM C 1585 [35] guidelines.Three specimens were tested per mix design, and the average result was reported.

Scanning electron microscope analysis
Scanning electron microscope (SEM) analysis of self-compacting concrete (SCC) involves a sophisticated examination of the concrete's microstructure.The technique utilizes a focused beam of electrons to scan the surface of prepared SCC samples, providing high-resolution images.This enables a detailed investigation into the arrangement and interaction of cement particles, aggregates, supplementary cementitious materials, and any additives present in SCC.SEM analysis is particularly valuable for assessing particle morphology, pore structure, and the distribution of phases within the concrete matrix.Additionally, it aids in identifying cracks, voids, and potential areas of weakness, contributing crucial insights into the material's durability, mechanical properties, and overall performance.

Energy dispersive X-ray spectroscopy analysis
The elemental composition of a sample can be ascertained using the energy dispersive X-ray spectroscopy (EDX) analysis.In order to get the sample to produce distinctive X-ray signals, it must be bombarded with X-rays.To help with both qualitative and quantitative material examination, EDX measures the energy and intensity of these emitted X-rays to reveal important information about the components included in the sample.

Slump flow test
The slump flow test measures the horizontal spread of the SCC sample after the mold (typically a cone) is lifted.In a desirable range (650 to 750 mm), the slump flow ensures good workability and flowability, allowing the concrete to reach all sections of the formwork easily.The SCC mix containing 3% arecanut fibers with a length of 12 mm exhibited the lowest flow diameter of 682 mm.This finding highlights the unique influence of these fibers on the SCC's flow behavior and workability.As the length and percentage of fibers increase, a progressive decrease in slump flow is observed.The results from laboratory tests, as illustrated in Fig. 3, support this trend.This emphasizes the critical importance of achieving the right slump flow within predetermined limits.By doing so, we ensure that the SCC retains the necessary workability and flowability-essential properties for successful placement and compaction, particularly in congested reinforcement applications.

T 500mm flow test
This test measures the time it takes for a SCC mixture to flow a specific horizontal distance, typically denoted as T 500mm .In the study, all T 500mm times were consistently less than 5 s, indicating slump flow rates within the desirable range of 2 to 5 s according to EFNARC specifications [30].This desirable range suggests good consistency and workability of the concrete mix for easy placement and filling of forms.Notably, the presence Fig. 3 Results of slump flow test of arecanut fibers in the SCC mix did not appear to significantly affect the flow time.The detailed data on T 500mm for each mix can be found in Fig. 4.

J-ring test
J-ring test values for SCC mixes containing arecanut fibers at various concentrations (1%, 2%, and 3%) and lengths (8 mm, 10 mm, and 12 mm) all fell well within the acceptable range for SCC according to the EFNARC guidelines [30].These guidelines specify a desired J-ring test result between 0 and 10 mm.A lower J-ring value indicates better performance, with minimal segregation of the concrete mix.Conversely, a value exceeding 10 mm suggests increased segregation, which can compromise the concrete's strength and uniformity.Figure 5 visually confirms this trend, where increasing the length and percentage of fibers leads to a higher J-ring value.

V-funnel test
In this study, the V-funnel flow times ranged from 6 to 9 s, which falls within the recommended range according to EFNARC guidelines [30].This indicates that all the tested mixes possess good filling ability.As detailed in Fig. 6, the control mix exhibited the fastest flow time of 6.21 s, signifying the greatest fluidity.Conversely, the mix containing the highest amount (3%) of 12 mm long arecanut fibers displayed the longest flow time of 8.92 s.This trend is visualized in Fig. 6, which clearly demonstrates that increasing the length and proportion of arecanut fibers leads to a rise in V-funnel flow time.This can be attributed to the increased friction and interference caused by the fibers within the SCC mix.

L-box test
The test results are quantified by the L-box ratio, where a lower value indicates better passing ability.Figure 7 summarizes the L-box ratios for different fiber contents.

Fig. 4 Results of T 500mm flow test
As expected, the trend shows a steady increase in the L-box ratio (indicating reduced passing ability) with increasing lengths and percentages of arecanut fibers.For instance, compared to the control mix, the L-box ratio dropped from 0.956 to 0.916 for concrete containing 3% of 12 mm long arecanut fibers.This suggests that longer and higher fiber content hinders the SCC's ability to flow through tight spaces.

Results of compressive strength test
Figure 8 summarizes the results of a 28-day compressive strength test.The addition of 10 mm arecanut fibers at a 2% volume fraction shows an increase in compressive strength compared to the control mix.However, this effect diminishes with higher fiber volume fractions (3%) or lengths greater than 10 mm.For reference, the target compressive strength for this project was 35 MPa.The SCC control mix achieved this target, and even showed a slight improvement of 9.25%.This demonstrates the effectiveness of the control mix design.Interestingly, the addition of arecanut fibers introduced a more complex relationship with compressive strength, as illustrated in Fig. 8.The bar graph shows that compressive strength generally decreased as the fiber content and length increased.However, there was a notable exception: the mix containing 10-mm long arecanut fibers at a 2% volume fraction exhibited the highest compressive strength.This specific combination resulted in a significant 15.14% increase in compressive strength compared to the control mix, highlighting the potential benefit of optimized fiber properties for SCC.At 2% volume fraction, the 10-mm fibers might be optimally dispersed within the concrete matrix.These 10-mm fibers might be long enough to effectively bridge cracks and micro-cracks within the concrete, acting as tiny internal reinforcements and arresting crack propagation.This bridging effect can lead to increased strength.When the fiber content increases to 3%, even with 10 mm lengths, there might be an overcrowding effect.This can lead to difficulties in achieving good fiber distribution within the concrete.Clumping of fibers can create weak spots and hinder the formation of a strong, cohesive matrix.

Results of splitting tensile strength test
Figure 9 showcases the splitting tensile strength of specimens tested at 28 days, incorporating various arecanut fiber volume percentages and lengths.The results demonstrate a progressive increase in splitting tensile strength with fiber inclusion, reaching a peak at a fiber length of 12 mm and 1% volume fraction.Importantly, all fiber-reinforced SCC mixes exhibited superior tensile strength compared to the control mix, signifying the overall benefit of fiber inclusion.The specimen with the highest splitting tensile strength corresponds to the 12 mm fiber length and 1% volume fraction, reaching 3.41 MPa, a significant 14.04% increase over the control mix's 2.99 MPa.These findings underscore the critical importance of meticulously selecting and optimizing the quantity and length of fibers in SCC mixes for achieving superior splitting tensile strength.

Results of flexural strength test
The effect of adding arecanut fibers and 30% fly ash on the flexural strength of selfcompacting concrete (SCC) is investigated in this study.This combination was expected to improve flexural strength in several ways.Firstly, by filling voids and increasing the overall uniformity of the concrete matrix, fly ash can reduce stress concentrations that lead to cracks.Secondly, fly ash can contribute to a denser microstructure, further enhancing crack resistance.Arecanut fibers were expected to bridge and arrest cracks that do initiate under tensile stress, due to their inherent tensile strength.Additionally, the anticipated good bond between the hydrophilic nature of arecanut fibers and the cementitious matrix in SCC was expected to provide a more effective crack arresting mechanism.Figure 10 illustrates that the greatest improvement in flexural strength was achieved with an optimal combination of fibers and fly ash content.The addition of arecanut fibers significantly increased flexural strength for various percentages and lengths, as shown in Fig. 10.The most favorable results were obtained with 1% of 12-mm long arecanut fibers, resulting in a flexural strength of 5.34 MPa.This represents a significant improvement of 35.87% compared to control SCC mix.However, beyond this optimal ratio, flexural strength began to decrease due to potential uneven distribution of the fibers within the concrete matrix.It is important to note that even at non-ideal Fig. 10 Results of flexural strength @28 days (N/mm. 2 ) fiber content and lengths, the flexural strength remained higher than the reference SCC mix.These findings demonstrate the potential of incorporating arecanut fibers, particularly at appropriate dosages, to enhance the flexural strength of SCC.

Results of rapid chloride ion permeability test
The results of the chloride ion permeability test, as shown in Fig. 11, demonstrate a significant improvement in chloride resistance in all tested SCC mixes containing fly ash and arecanut fibers cured for 28 days.All SCC mixes achieved relatively low chloride ion penetrability, with Coulomb charges below 2000 coulombs.This translates to a potential increase in the concrete's resilience to corrosion and extended lifespan in environments with harsh conditions.Figure 11 shows that incorporating 30% fly ash along with varying amounts of arecanut fibers into the self-compacting concrete (SCC) mix effectively reduces the measured Coulomb charges.The control SCC mix without any additives exhibited the highest charge (1823 C), indicating the most significant chloride ion penetration.In contrast, all SCC mixes containing arecanut fibers (denoted as SCC F1%, F2%, and F3% with fiber lengths of 8 mm, 10 mm, and 12 mm respectively) displayed a reduction in measured charges.This signifies enhanced resistance to chloride ion ingress.The improved performance can be attributed, at least in part, to the presence of fly ash and arecanut particles within the concrete matrix.These particles effectively filled voids and acted as a physical barrier against the movement of charged chloride ions.For reference, the acceptable limits for chloride ion permeability as per ASTM C1202 [34] standards are presented in Table 8.These findings strongly support the use of fly ash and arecanut fibers as effective methods to improve the resistance of SCC to chloride ion penetration, ultimately contributing to a longer lifespan for SCC structures.

Results of sorptivity test
The addition of fly ash and arecanut fibers can alter the sorptivity of self-compacting concrete (SCC).Lower sorptivity is generally desirable as it reduces water ingress and potential for damage caused by moisture expansion or freeze-thaw cycles.Figure 12(a) and (b) demonstrate the initial and secondary water absorption of the SCC samples, illustrating the steady rise in water absorption over time.Interestingly, the data show that increasing the amount and length of arecanut fibers leads to an increase in water absorption.This can be attributed to the inherent properties of the arecanut fibers themselves.Arecanut fibers, derived from the betel nut palm, have a naturally porous structure and hygroscopic character, meaning they readily attract and hold moisture.The increased water absorption with more fibers is likely due to their ability to act like tiny sponges within the SCC.
These findings highlight the complex interplay between fly ash and arecanut fibers in influencing SCC's sorptivity.While fly ash generally reduces water absorption, the effect of arecanut fibers is more nuanced, depending on factors like their distribution within the concrete mix, orientation of the fibers, and their intrinsic qualities.This emphasizes the importance of carefully considering material composition and properties when designing SCC.

Scanning electron microscope results
Scanning electron microscope (SEM) analysis provides high-resolution micrographs that reveal the microstructure of self-compacting concrete (SCC) at a magnified scale.This technique is crucial for understanding how the incorporation of fly ash and arecanut fibers influences the concrete's properties.Figure 13 showcases the micrograph of self-compacting concrete (SCC) without any additives (standard mix).This micrograph reveals a substantial presence of calcium silicate hydrate (C-S-H) gel in the examined sample, crucial for strength and durability.In the absence of additives such as fly ash and arecanut fibers, noticeable micro-pores and cracks are evident, indicating a non-uniform microstructure and potential vulnerabilities.These imperfections may contribute to the subpar strength and durability of unblended SCC mixes compared to blended counterparts, emphasizing the crucial role of supplementary materials like fly ash in fortifying concrete and enhancing the overall performance.
The SEM analysis also focuses on the effects of incorporating 30% fly ash as a partial cement replacement, alongside varying lengths of arecanut fibers (8 mm, 10 mm, and 12 mm).By examining the micrographs (Figs.14, 15, and 16), researchers can assess how fly ash alters the hydration products (the microscopic components formed during cement setting) and the overall microstructure.Additionally, the analysis reveals how different fiber lengths and content influence the distribution of these phases within the concrete.Understanding how fiber length affects the orientation and dispersion within the concrete matrix is crucial for enhancing its mechanical properties.SEM images allow for a closer look at the pore structure and cracking patterns, providing valuable insights into the interactions and bonding between the cementitious matrix, fly ash, and arecanut fibers.

Energy dispersive X-ray spectroscopy results
The crystalline structure of minerals in self-compacting concrete (SCC) is crucial for understanding its mechanical properties and long-term performance.This study uses energy-dispersive X-ray spectroscopy (EDX) analysis to examine the composition of these minerals, particularly focusing on calcium (Ca) content.As the primary component of Portland cement, calcium plays a significant role in the hydration process, which forms the binding matrix that holds the concrete together.
Figure 17 shows the EDX analysis graph of the control SCC mix.This mix has the highest percentage of calcium and oxygen elements, indicating the presence of calcium-rich phases commonly associated with Portland cement hydration products.The main crystalline phases identified by EDX are calcium silicates, formed during the hydration reaction between cement and water.The increased presence of these elements contributes to the enhanced mechanical properties of the control SCC mix.In comparison, Fig. 18 showcases the analysis of SCC containing fly ash.This mix exhibits a decrease in the calcium (Ca) percentage compared to the control mix.However, it shows a significant increase in oxygen and silicon, reflecting the composition of fly ash itself.These elements also contribute to the improved properties of SCC, although through different mechanisms.Table 9 details the weight percentages of key constituents in both the control SCC mix and the fly ash admixed SCC mix.By understanding the mineralogical makeup of SCC through EDX analysis, scientist's or engineers can predict the mechanical and chemical properties of the concrete.By analyzing the elemental composition using EDX, researchers gain valuable insights into the mineralogical makeup of SCC.This information allows scientists or engineers to understand the relationship between the material's microstructure and its mechanical and chemical characteristics.

Fig. 11
Fig. 11 Results of rapid chloride ion

Fig. 13
Fig. 13 SEM image of control mix

Table 1
Characteristics of cement

Table 2
Chemical properties of fly ash

Table 3
Physical properties of arecanut fiber

Table 4
Characteristics of M-sand

Table 5
Characteristics of coarse aggregate

Table 6
Properties of admixture

Table 7
Mix proportions of SCC mix CA Coarse aggregate, FA Fine aggregate, SP

Table 8
[34]ride-ion permeability according to ASTM C-1202[34] Fig. 12 a Initial rate of water absorption.b Secondary rate of water absorption

Table 9
EDX analysis of control SCC mix and SCC containing fly ash (30%)