Implementation assessment of calcined and uncalcined cashew nut-shell ash with total recycled concrete aggregate in self-compacting concrete employing Bailey grading technique

The present study concentrates on the performance evaluation of calcined and uncalcined cashew nut-shell ash (UCCNA and CCNA) with treated total recycled concrete aggregate (TRCA) in self-compacting concrete. The achievement of sustainable self-compacting concrete (SCC) is possible by the implication of four stages, which includes TRCA treatment process, gradation selection process through Bailey aggregate grading technique, by considering TRCA replacement percentage with an increment of 25% and up to 100% and by considering UCCNA or CCNA replacement with an increment of 5% and up to 20%. Hardened and fresh properties of SCC have been performed and analyzed based on the compliance requirements of SCC. In addition finding results through microstructure assessment was in line with the findings of the hardened and fresh properties of SCC. In addition, quality and dynamic instability assessments of SCC were analyzed through ultrasonic pulse velocity and drying shrinkage aspects. Besides CO2, the emission rate and the efficiency rate of SCC, composites were analyzed in detail. Overall findings revealed that CCNA-based SCC mixes performed effectively than UCCNA-based SCC; specifically, incorporation of 75% of TRCA with 15% CCNA was found to be optimal. But with regard to shrinkage performance UCCNA found to be better by imputing less shrinkage compared to CCNA-based SCC mixes. Further with regard to efficiency rate of SCC composites revealed the gain of maximum efficiency of about 0.156 MPa/kg CO2/m3 and 0.160 MPa/kg CO2/m3 for 15% and 20% CCNA-based SCC mixes.


Introduction
Utilization of agro-waste materials as cementitious or pozzolanic in versatile concrete was found to be more frequent. Most utilized agro-wastes in concrete are rice husk ash, bagasse, groundnut shell ash, oyster shell ash, sawdust ash, and cork waste ash [1][2][3]. Most of these agro-wastes must undergo a calcination process, which results in property enhancement [2,4,5]. Usually, these processes were executed at a higher temperature of about 400-800 °C depending on the agro-waste nature [2,4,6,7]. However, in the perceptive of time dependency, energy consumption and environmental benefits make the final product less sustainable [8,9]. Developing countries like India, which is the thirdlargest producer of cashew nut in the world, perform disposal of cashew nut-shell with an uncontrolled burning technique [10,11]. These under-burnt cashew nut-shells (< 400 °C) produce un-calcined cashew nut-shell ash (UCCNA) with more unburnt carbons [12]. Calcined (400-800 °C) cashew nut-shell ash (CCNA) produces whitish and greyish particles which is the representation of crystallization of silica [12,13]. Literature reveals about two types of CCNA which are bifurcated as CaO-based CCNA (35.67% max) and SiO 2 -based CCNA (62.85% max) [12][13][14][15]. These two CCNA variants impart diverse nature in the fresh and hardened properties of concrete. Implication SiO 2 -based CCNA with ordinary portland cement (OPC) enhances the slump flow and compaction factor properties due to the low quantification or absence of CaO, which implies retarder behaviour in cement paste at the initial state of hydration [15]. CaO-based CCNA imparts a decreasing nature in slump flow performances because the presence of high quantified CaO accelerates the hydration process in cement paste. Limited studies were executed and addressed towards the comparison of calcined and uncalcined agro-waste products on concrete applications [14]. To date, optimum utilization of CCNA is proposed up to 15%, 20%, and 25% recommended by Oyebisis et al., Thirumurugan et al., and Pandi et al., respectively [13,15,16]. However, to date, no study is performed on the utilization of UCCNA in concrete paste appliances. In addition, oxide nature variance of CCNA from source to source promotes the scope of research.
Aggregate is a predominant material that is used on a vast scale in the construction industry. Due to the better durability of igneous rock-based aggregates, granite and basalt are most preferred and utilized in the construction industry to date [17][18][19]. In India, aggregate flow analysis revealed that 99% of the produced stone is utilized in concrete, and its demand is about 1.089 billion tonnes per annum [17,20]. The stone process has a significant impact on air pollution, not least in terms of CO 2 emissions from the use of fossil fuels and electricity [17,18,21]. Utilization of total recycled concrete aggregates (TRCA) in concrete is the way forward for the environmental benefits. In addition utilization of TRCA in concrete helps to mitigate the CO 2 emissions from the processing of natural stone into aggregate. Natural aggregate processing involves quarrying, crushing and transportation which leads to the production of 20 kg of CO 2 /1000 kg of natural aggregates [18]. On the other hand processing of 1000 kg TRCA roughly saves 8 kg of CO 2 [18,20] . In India, in the future, if all of the aggregates are replaced by TRCA in concrete, it will save 8 million tonnes of CO 2 per annum [17,18]. TRCA represents the inclusion of both recycled coarse and fine aggregates, which is found to be more suitable for structural concrete because of its favourable characteristics to those of reclaimed asphalt pavement aggregates and mixed recycled aggregates [22][23][24]. In addition, TRCA has a crucial influential hold on concrete properties due to its adhere mortar. Its impact on the concrete property was more significant as the increase of replacement percentage [25][26][27][28][29]. As far as this, vast studies were carried out for concrete with coarse TRCA. Many developed nations accept the TRCA coarse as a major construction material [30]. On antithesis, very few studies have been made regards TRCA fines, and many countries do not recommend utilizing it in actual construction practices [22,30]. It may be due to the uncertain property behaviour of TRCA fines in composite concrete. It promotes the vast study, especially from 2004 onwards many studies recommend utilizing TRCA fines in concrete with procured limitations [28,31]. Particle packing methods have been considered as one of the procured methods to mitigate the drawbacks of TRCA on concrete performance. Bailey aggregate grading technique (BAGT) is a particle grading tool, which was initially proposed for asphalt mixes [32][33][34]. However, this technique was found to be most suitable for self-compacting concrete (SCC) where it was purely based on the particle orientation factor, which was necessary where it would be expected that aggregate must self-orient itself to achieve the densified compacted state [35,36]. Further BAGT was found to be more suitable for recycled-based SCC [37]. However, to date, no study has been performed by utilizing BAGT with TRCA in SCC, and it was found to be a research scope of interest.
The application of SCC was found to be vast in the current construction industry. In addition, trial and error-based practical-oriented SCC mix design promotes research, and presently vast studies are practised [38,39]. Pereira-de-Oliveira et al. [40] and Grdic et al. [41] studies revealed that the inclusion of TRCA in SCC slightly reduced rheology and mechanical properties. However, the study of Fakitsas et al. [42] and Khodair and Bommareddy [43] revealed that TRCA inclusion significantly promotes compressive, tensile, and shear strength of SCC. It represents the complex behaviour of TRCA in SCC, and it depends on TRCA characteristics which rely on TRCA treatment or adhere mortar quality and content. To date, several treating procedures were adopted to enhance the adhere mortar property or to reduce the adhere mortar thickness around the TRCA [44]. Mechanical grinding, selective heat grinding, heat grinding, pre-soaking water, and pre-soaking in acids were practised procedures for removing adhered mortar from TRCA [45][46][47][48]. It was observed that adaptation of these physical treatments succeeded to impart 7% more mechanical properties at the age of 28-day curing period [44]. Still, these procedures challenge the TRCA toughness, texture, and bonding characteristics which were necessary to address regards of durability aspects of concrete [49,50]. Polymer emulsion, filler lime powder, calcium carbonate deposition, pozzolanic solution, sodium silicate, and carbonation were practised for strengthening the adhere mortar properties of TRCA [51][52][53][54][55][56]. These procedures to date challenge the economy, demand of skilled labour, durability, and adaptation flexibilities in real-time practices. In the present investigation, these challenges promote the adoption of novel freezing-thawing cyclic treatment to TRCA; this treatment aims to enhance the brittleness property of adhering mortar, which further assists for the easier removal when TRCA is subjected to external impact loading. The further study aims to develop a sustainable TRCA incorporated SCC mix through the BAGT method. The adaptation of BAGT aims to determine the best suitable replacement of TRCA in terms of both coarse and fine aggregates, which are based on the compliance requirements of compressive strength, flexural strength, and modulus of elasticity as per IS 456: 2000 [57]. Further, the performance of TRCA incorporated SCC was evaluated with CCNA and UCCNA.

Binder materials
Preliminary binder responsibility was taken care of by OPC with the density of 3140 kg/m 3 , and mineral addition including class F-Fly-Ash (FFA) with the density of 2810 kg/m 3 , UCCNA with 2890 kg/m 3 , and CCNA with 3110 kg/m 3 was used as powder material in the SCC mixture. Detailed chemical composition and physical properties of FFA, UCCNA, CCNA, and OPC are presented in Table 1. The chemical composition reveals about pozzolanic nature of FFA, UCCNA, and CCNA as the summation of SiO 2 , Al 2 O 3, and Fe 2 O 3 was found to be 89.99%, 50.31%, and 52.24%, respectively. In addition to this, CCNA even represents the cementitious properties because it has 25.80% of CaO. The physical appearance of binders was evaluated through Field Emission Scanning Electron Microscopy (FE-SEM) images on Carl Zeiss, Oxford equipment that assisted in understanding the particle morphology of binders. Figure 1 reveals the spherical structure of FFA and dense structure of OPC, CCNA, which have been taken with 5 kV acceleration voltages at a 2.8-4.5 mm working distance. CCNA represents the presence of voids due to the burnout of carbon during calcination [58]. UCCNA represents mediumto small-sized particles, which indicates the uncertainty of particle shape, size, and structure. In addition, the FE-SEM spectrum images have been confirming the presence of pozzolanic elements like Ca, Si, Al, O, and Fe concerning all binder variants. Figure 2 represents X-ray diffraction (XRD), particle size distribution, thermo-gravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FTIR) analysis of binder materials. Figure 2a Table 2. Particle fraction details of binders are presented in Fig. 2b, which revealed that UCCNA was found to be coarser followed by OPC, CCNA, and FFA. The mean diameter (d 50 ) of CCNA and FFA was found to be 9 µm and followed by the mean diameter (d 50 ) of UCCNA and OPC to be 15 and 14 µm. Figure 2c represents the TGA performance  [61].
In the context of pozzolanic material, peaks at 1098 cm −1 , 1072 cm −1 , and 1068 cm −1 of FFA, UCCNA, and CCNA may represent the presence of CO 3 . In the fingerprint region of FTIR (600 cm −1 to 1400 cm −1 ) comparison of CCNA and UCCNA more or less was found to be a closer impression. This may be due to the presence of similar chemical bonds. Overall microstructure assessment of binders about microtexture, compounds, particle fractions, combustion behaviour, and identified chemical bonds was in line with the oxide composition of binders.

Natural aggregates (NA)
For the preparation of control mix (CM) with 100% natural aggregate, 20 mm down locally available natural crushed coarse aggregates were utilized. River sand having a size less than 4.75 mm was utilized as fine aggregate. In addition to SCC mixes, the emphasis was switched away from natural aggregates and towards TRCA replacement.

Total recycled concrete aggregates (TRCA)
TRCA was extracted from concrete laboratory waste. Further bifurcation of these aggregate was carried through a drilling  Fig. 3b refining of destressed TRCA was carried through the aggregate grinding machine; further, TRCA coarse aggregates (≥ 4.75 mm) and TRCA fines (≤ 4.75 mm) were collected and stored separately. Further treatment to TRCA fractions was necessary to remove the adhering mortar because the previous investigation revealed that the presence of adhering mortar significantly reduces the concrete characteristics [41,64,65]. In addition, SCC rheological performance was significantly reduced while utilizing untreated TRCA as a major source of an aggregate fraction [66][67][68]. To encounter these uncertainties, ageing protocols for TRCA fractions were purposefully carried out. In this, TRCA aggregate underwent freezing and thawing cyclic procedure, which imparts brittle property in adhering mortar of TRCA. It is necessary for easy removal of adhering mortar while experiencing the impact loading in the ABAT chamber. Further, these aggregate fractions were sieved ( Fig. 4) and stored separately.

Chemical admixture
For the promotion of rheological properties of a concrete mixture, a superplasticizer (SP) based on modified  polycarboxylic ether polymer with a specific weight of 1.085 kg/litre and pH of 6 was used. The manufacturer recommended a dosage range of 0.5-3.0 L/1000 kg of cementitious materials.

CCNA preparation process
CCNA made from cashew nut shells was sun-dried for 14 days before being calcined in a gas furnace chamber at 750 °C for 8 h. It was also sieved through 45 m for fraction separation to match the particle size of OPC.

TRCA optimization with novel freeze and thaw cyclic treatment
Initially, fractioned TRCA is underwent heat treatment. TRCA was kept in an oven by maintaining the temperature of about 250 °C for about 24 h. Further TRCA was cooled down to room temperature and adhere mortar removing process was executed in the ABAT chamber. As in Fig. 5, it was found that 10 CB would be optimal because further increment of CB was found to be insignificant towards the removal of adhering mortar from TRCA, which results in no change in water absorption (WA). For the further removal of adhered mortar, these TRCA aggregates undergo freezing and thawing (F&T) cycles. In this, TRCA was sealed in plastic bags and kept in a freezer at − 18 °C for 24 h. Further unwrapped TRCA was carted out and kept in the container with water immersion at 80 °C for 24 h, which implies one cycle completion. This experiment reveals seven cycles as optimal, and adaptation of twelve cycles was found to be insignificant regards the removal of adhering mortar from TRCA. Figure 6 is the representation of the physical characteristics transition of TRCA throughout the treatment process. As per previous studies and IS 383 [69] aggregate particles were restricted to 150 µm or more, and particles less than 150 µm were considered as binder particles or fillers. This promotes the rejection of fine TRCA of about 75 µm or less from the present investigation. Further, treated TRCA were fractioned through sieves and stored as Coarse TRCA (C-TRCA) and Fine TRCA (F-TRCA). Figure 7 demonstrates the final appearance of each TRCA fraction, and it was found that on average, 2.94% and 3.91% WA characteristics remained in treated C-TRCA and F-TRCA fractions, respectively.

Gradation optimization utilizing the Bailey aggregate grading technique
Bailey's aggregate grading technique (BAGT) allows the gradation selection based on nominal maximum aggregate size (NMAS = 20 mm) and particle orientation factor (POF). Characterization of NA and TRCA aggregate is as in Table 3. In SCC, it was expected that concrete must gain the flowing, filling, and passing ability, which primarily relies on mortar and aggregate orient fraction. In the context of aggregate orient fraction, BAGT was the most suitable technique regards gradation selection for SCC. POF was measured based on loose unit weight (LUW) and rodded unit weight (RUW) of aggregate characteristics. LUW was a representative of POF of aggregate without external effort, and RUW was a representative of POF of aggregate at three-layer compacted state. BAGT prefers the selection of gradation based on the self-orientation of aggregate particles without external effort through the blending process, which results in the selection of chosen unit weight (CUW). CUW is always lying around LUW and RUW. As per BAGT, CUW must fall in between 95 and 105% of LUW. In the present design, CUW was considered equivalent to LUW or CUW = 100% of LUW. The reason behind these considerations was to eliminate the gradation packing error, which might occur in SCC as further selected gradation must compensate with cement mortar with the least ± 5% variance of LUW. previous studies, the average particle diameter ratio ranges from 0.15 (for round and hexagonal close-packed particles) to 0.42 (consideration of flat and cubical packed particles) [32,34,36,37]. Exploration of particle packing revealed that particle packing follows various models, with the trademark measurement being above or below 0.23 proportions, so 0.23 was considered to be the normal state of packing design [32,37]. In the present study, 20 mm was NMAS, 10 mm was HS, 4.75 mm was PCS, 1.18 mm was SCS, and 0.3 mm was TCS. In addition, POF and gradation boundary conditions were evaluated and controlled through coarse aggregate ratio (Ca-ratio) (Eq. 1), fine aggregate coarser ratio (Fac-ratio) (Eq. 2), and fine aggregate finer ratio (Fafratio) (Eq. 3) which were collectively called Bailey ratios.
BAGT recommended Bailey ratio ranges from 0.6 to 0.75 for Ca-ratio and 0.35 to 0.5 for Fac-ratio and Faf-ratio. Bailey ratios must be between recommended ranges after gradation design to ensure better particle orientation, interaction, and packing.

Mix design as per compliance requirement of SCC
The present study aims to develop a sustainable SCC mix of M40 grades. Cement being a primary binder contributes 75% and FFA being a secondary binder contributes  (5) and (6) [57]. Once after the identification of possible maximum replacement percentage of C-TRCA, it was decided to be kept constant for further additional all SCC mixes.
where f ckt is characteristic strength of concrete and it is 40 MPa for M40 grade.
σt is the standard deviation and it is found to be 5 for M40 grade concrete as per IS 456 [57].
In addition to SCC mixes, C-TRCA percentage (based on MR) was kept constant and F-TRCA was introduced at a 25% incremental range up to 100% replacement. The possible maximum replacement percentage of F-TRCA was further determined based on the compliance requirements of SCC. Further, it was decided to keep these identified MR percentages of C-TRCA and F-TRCA constant in supplementary SCC mixes. As observed from Table 3, the change in unit weight percentage of coarse NA (10.47%) and C-TRCA (10.82%) was found to be similar. However, the difference in change in unit weight percentage between fine NA (0.37%) and F-TRCA (3.26%) was found to be 2.89%. It revealed poor particle orientation and poor compacting abilities of F-TRCA. The presence of more adhered mortar in F-TRCA would be the reason for poor performance. Further, it was necessary to perform optimization by altering the incorporated percentage of F-TRCA and it was carried out. As detailed in Table 4, the incorporated percentage of F-TRCA was altered between 75 and 95% in SCS with an incremental trend. At the same time, F-TRCA introducing percentages in TCS and TCSP were reduced from 75 to 65% at a decremental trend. As a finalized result, an optimized SCC mix was chosen based on compliance requirements of rheological and mechanical properties. Extended SCC mixes were performed with the aim of paste optimization by replacing cement with UCCNA and CCNA at a 5% replacement rate up to 20%.

Microstructure evaluation of SCC binders
Microstructure evaluation was carried out for paste combinations. Field Emission Scanning Electron Microscope (FE-SEM) test by employing Carl Zeiss FE-SEM, Oxford instrument was performed on OPC, followed by binary and ternary binder combinations. Mineralogical compounds and chemical formulas of chemical constituents were examined by XRD spectroscopic analysis, and it was performed using a Rigaku Mini-flex with an angle measurement of (5°-130°) 2θ value. Energy-dispersive spectroscopy (EDS) was performed on binary and ternary binder combinations to investigate and measure the chemical elements of binder residues. TGA procedure was utilized to determine the thermal characteristics of binary and ternary binder combinations. TGA was accomplished in the selection of 30-790 °C at the rate of 10 °C/minute utilizing the discovery series TA-55 instrument. FTIR utilizing JASCO FT/IR-6300 with a wavelength range of 400-4000 cm −1 was performed on binary and ternary paste combinations. In the context of microstructure evaluations, regard, all binders were performed respective tests at the age of 7 (early stage of curing) and 90 (later stage of curing period) days. . As per standards, UPV values varying between less than 3000 m/s, 3000 m/s to 3500 m/s, 3500 m/s to 4500 m/s, and more than 4500 m/s concrete quality were evaluated as weak, modest, adequate, and excellent. In addition, drying shrinkage, WA, and density parameters of SCC were also evaluated to recognize the qualified performance of concrete along the same lines (Fig. 8).

Fresh state properties of SCC
Fresh state properties of SCC were evaluated based on the flowing ability and viscosity class. The increase of C-TRCA and F-TRCA reduces the flowing ability of SCC, which results in higher viscosity. As the percentage contribution of TRCA increases, WA in the overall mix increases, which was the preliminary reason for the drop of slump flow, slump T 500, and V-funnel performances [75][76][77]. However, poor particle orientation characteristics of TRCA (change in unit weight percentage of F-TRCA is 3.26% as in Table 3) was the secondary reason for the reduction of fresh state characteristics of SCC. In addition, the preparation process of TRCA produces more irregularity regards aggregate shape, texture, which makes it difficult to flow in a blended paste [66,78,79]. All SCC mixes successively achieved the minimum fresh-state requirements, which included slump T 500 (  TRCA-CA75-FA75-2 enhances relative performances of slump flow, slump T 500, and V-funnel by 3.27%, − 4.92%, and − 5.24%, respectively. Overall TRCA-CA75-FA75-2 was the optimized TRCA-based SCC mix, which sustained the identical performance of TRCA-CA25 with a higher superplasticizer demand of about 1.860 kg/m 3 . Further performance of TRCA-CA75-FA75-2 was analyzed in the presence of UCCNA. In the presence of UCCNA, 5% (TRCA-CA75-FA75-2-UCCNA5) relative slump flow was increased by 1.23% and even the same performance was sustained at 10% UCCNA (TRCA-CA75-FA75-2-UCCNA10) replacement. Synchronously slump T 500 and V-funnel relative performance were reduced by − 1.17% and − 1.02% at 5% to 10% UCCNA replacement levels. The presence of more unburnt carbon (confirmed by TGA analysis as in Fig. 2c) retards the initial state of hydration when gets contacted with water, and UCCNA was much finer than OPC (confirmed by particle size distribution analysis as in Fig. 2b); its d 50 (14 µm) and d 10 (2.4 µm) were finer than that of OPC d 50 (15 µm) and d 10 (3.8 µm), which resulted in improved fresh-state performances of SCC up to 10% UCCNA level. At further replacement level (TRCA-CA75-FA75-2-UCCNA15 and TRCA-CA75-FA75-2-UCCNA20) decremental trends regard of fresh state performances of SCC has appeared. The presence of uncertain UCCNA particle distribution (UCCNA d 90 (36) > OPC d 90 (32) as in Fig. 2b) may retard the fresh state properties of SCC at higher replacement levels of about 15% and 20%.
In addition, TRCA-CA75-FA75-2 was analyzed in the presence of CCNA. It was evident that as the increase of CCNA partial replacement percentage was by 5-20%, a reduction in fresh state properties was found. Usually, calcined agro-waste has a higher rate of reaction phase [2,5], specifically with the presence of higher CaO (25.80%) and Fe 2 O 3 (27.93%) in CCNA, which accelerates the initial hydration process [15]; in addition, CCNA (d 50 = 9) was much finer than OPC (d 50 = 15) which categorizes CCNA as higher reactive phase material, which results in the reduction of fresh state properties. As per relative slump flow, relative slump T 500, and relative V-funnel, maximum performance drops were found for TRCA-CA75-FA75-2-CCNA20 by − 2.29%, + 3.05%, and + 3.04%, respectively.

Compressive strength of SCC
Compressive strength will be the core representation method regards to all types of concrete. In comparison with CM, it was found that as the replacement percentage of TRCA increases, decremental compressive strength was found. As per the compliance requirement of concrete, it was found that 75% (TRCA-CA75 and TRCA-CA75-FA75) will be the possible MR percentage regards to both the coarse and fines of TRCA through BAGT. Further replacement failed to fulfil the minimal compliance requirements of concrete. The presence of adhered mortar was the culprit that weakened the interfacial transition zone (ITZ) and became responsible for earlier failure of bonding between the packed aggregate regards TRCA-based SCC [80,81]. In addition, relative compressive strength revealed maximum differentiation, specifically in SET-2 at the age of 7 days as in Fig. 9. Maximum decremental relative compressive strength was observed for TRCA-CA75-FA75 and TRCA-CA75-FA100 at the age of 7 days, and it was about − 15.42% and − 19.87%. It was evident that the presence of adhering mortar retards the earlier stage of hydration, which weakens the ITZ. Further gradation optimization through BAGT was carried out by minimizing F-TRCA in TCS and TCSP and by the same percentage of F-TRCA introduced in SCS, which improvised the compressive strength. Specifically for TRCA-CA75-FA75-2, incremental relative compressive strength was found at about + 19.11% at the age of 7 days. It was evident that a restriction of 1.18 mm or less sized F-TRCA aggregate through BAGT significantly promoted earlier age of compressive strength in TRCA-based SCC. Overall, as in Fig. 10, TRCA replacement was found to be significant concerning to compressive strength of TRCA-based SCC with 0.90 and 0.96 R 2 values. The introduction of the prioritized UCCNA binder to TRCA-CA75-FA75-2 imparts negative performance. Exclusively, TRCA-CA75-FA75-2-UCCNA20 gained − 16.62% relative compressive strength. It was evident that the presence of more unburnt carbon (as in Fig. 2c), retards the hydration and imparts weaker ITZ structure in and around the TRCA, which results in poor performance. However, as per the compliance requirement of concrete, all UCCNAbased SCC mixes successfully fulfilled the minimal requirement. In addition, TRCA-CA75-FA75-2-UCCNA5 and TRCA-CA75-FA75-2-UCCNA10 were found to be optimal mixes. Further introduction of prioritized CCNA binder to TRCA-CA75-FA75-2 imparts inventiveness regards compressive strength of SCC. As stated in Sect. 4.1, the presence of CaO (25.80%) and Fe 2 O 3 (27.93%) in CCNA, accelerated hydration. Furthermore, CCNA (d 50 = 9) was much finer than OPC (d 50 = 15), classifying CCNA as a higher reactive phase material, resulting in ITZ as a dense composite structure. TRCA-CA75-FA75-2-CCNA15 was found to be an optimized SCC mix with + 14.94% of relative compressive strength. In addition, the relation between compressive strength versus UCCNA or CCNA replacement percentage was examined with a polynomial fit and it was found to be significant with 0.81 and 0.89 R 2 values.

Flexural strength of SCC
Performance evaluation of flexural strength revealed the same trend as of compressive strength characteristics of TRCA-based SCC. It was found that TRCA-CA100, TRCA-CA75-FA100, and TRCA-CA75-FA75-2-UCCNA20   were failed to fulfil the minimal compliance requirement of SCC and left-out SCC mixes were succeeded to fulfil the same as in Fig. 11. With the increase of TRCA, the WA rate of SCC also enhances. It exhibits more water demand required for the hydration process, which may result in poor construction of ITZ [82][83][84]. In addition, the presence of adhering mortar weakens aggregate interlocking characteristics (Refer Table 3), which results in poor flexural properties of TRCA-based SCC. The relative performance of TRCA-CA75-FA75-1 and TRCA-CA75-FA75-2 represents an increase of 22% and 33.33% at the age of 7 days, respectively. It comes with the agreement that a reduction of 1.18 mm or less with the implication of BAGT enhanced the packing characteristics, which resulted in significant improvements of earlier strength of TRCA-based SCC. In addition, the relation between TRCA replacement percent versus flexural strength (Fig. 12) was found to be significant with a 0.89 R 2 value.

T R C A -C A 7 -F A 7 -2 -C C N A 1 0 T R C A -C A 7 -F A 7 -2 -C C N A 1 T R C A -C A 7 -F A 7 -2 -C C N
Performance of TRCA-CA75-FA75-2 with UCCNA blended binder was found to be failed regards improvement of relative flexural strength. Flexural performance of TRCA-CA75-FA75-2-UCCNA5 and TRCA-CA75-FA75-2-UCCNA10 was found to be similar in regard to 7, 28, and 90 days. As stated in Sect. 4.2, UCCNA has more unburnt carbon, which resulted in poor performance.
CCNA blended binder with TRCA improved the flexural performance of concrete, and it was found that TRCA-CA75-FA75-2-CCNA15 can be optimal. Relation revealed that the implication of UCCNA (R 2 = 0.98) and CCNA (R 2 = 0.93) has a significant influence over flexural characteristics of TRCA-based SCC.

Split tensile strength of SCC
Split tensile strength of concrete is in agreement with compression and flexural performance. As the replacement percentage of TRCA increases, a decremental trend was observed regards the tensile properties of concrete as in Fig. 13. Specifically, the implication of BAGT was found to be advantageous.
TRCA-CA75-FA75-1 and TRCA-CA75-FA75-2 succeeded in representing incremented relative split tensile strength of about 15.75% and 32.62% at the age of 7 days. In addition, as in Fig. 14 the relation between split tensile strength and TRCA replacement was found to be significant with 0.81 and 0.82 R 2 values.
Performance of TRCA-CA75-FA75-2 with CCNA prioritized binder was found to be enhanced. TRCA-CA75-FA75-2-CCNA15 was found to be optimal performed SCC mix. Simultaneously, the relation between split tensile strength and CCNA or UCCNA replacement was found to be less significant with 0.76 and 0.85 R 2 values.

Modulus of elasticity of SCC
The elasticity of concrete represents a decremental trend as the increase of TRCA replacement percentage as in Fig. 15. These results are in line with compression, flexural, and split tensile strength characteristics of concrete. The presence of adhering mortar around the TRCA improves the brittleness property of overall SCC, which results in poor elasticity [85]. Still, most of the TRCA-based SCC were succeeded to fulfil the compliance requirement except TRCA-CA100 and TRCA-CA75-FA100. In the context of BAGT, it was found that restriction of 1.18 mm or less sized TRCA became beneficial for the improvement of relative modulus of elasticity of about 4.01%, regards TRCA-CA75-FA75-2 SCC mix. Furthermore, as in Fig. 16 the linear relation between modulus of elasticity and TRCA replacement was found to be significant with 0.98 and 0.80 R 2 values. Elasticity performance of TRCA-CA75-FA75-2 in the presence of UCCNA was found to be neutral (less than 0.43% relative modulus of elasticity were observed) regards 5% and 10% replacement levels. Further UCCNA replacement, specifically at 15% and 20%, imparted a reduction of − 1.04% and − 1.68% of relative modulus of elasticity. However, all UCCNA-based SCC mixes were succeeded to fulfil the compliance requirements. Besides the elasticity, the behaviour of TRCA-CA75-FA75-2 in the presence of CCNA was found to be incremental up to 15%, though relative modulus of elasticity was found to be similar and was about in and around 5%. At 20% CCNA, a decremental trend regards relative modulus of elasticity was observed. Altogether, retains between modulus of elasticity and CCNA or UCCNA replacement were found to be significant with 0.860 and 0.96 R 2 values.

SEM examination of SCC binders
Microstructure images of OPC, binary, and ternary pastes were taken with a working distance of about 2.3-4.2 mm, and lower voltages (5 kV) were used to avoid charging disturbances. Each microstructure image was taken with a magnification of 10 kx at the age of 7-and 90-day curing period. Observation OPC at the age of 7 and 90 days (Refer Figs. 17a and 18k) revealed calcium-depleted paste with a new class of microcracks, which appeared due to the heat of hydration [86]. This is due to un-hydrated calcium hydroxide platelets in the concrete matrix, as well as small CSH fibres that cover the anhydrous calcium silicate grains of calcium silicate [37,87]. It demands supplementary pozzolanic materials to compensate for microcracks, and at present, the addition of FFA as a partial replacement to OPC fulfils the demand. FFA generally consists of Al, Si, and K (as in Fig. 1) with an average particle size of about 9 µm (as in Fig. 2b). FFA probably adsorbs Ca ion at an early hydration age, which gives an appearance of a microcrack-free structure by minimizing the gap (0.5-1 µm) between CH crystals parallel to the cleavage plane was often observed [86].
A ternary combination of pastes was examined with UCCNA and CCNA as a prominent constituent ingredient. Observation revealed the presence of un-hydrated FFA in the ternary paste at the age of 7 days. However, in the context of UCNNA and CCNA, the growth of hydrated products attached with un-hydrated FFA was only observed in CCNA prominent ternary binders. Specifically, these observations were found for OPC+FFA+CCNA5 (Fig. 17g), OPC+FFA+CCNA10 (Fig. 17h), and OPC+FFA+CCNA20 (Fig. 17i), in comparison with OPC+FFA+UCCNA5 (Fig. 17c), OPC+FFA+UCCNA10 (Fig. 17d), and OPC+FFA+UCCNA20 (Fig. 17e) at the age of 7 days. The presence of unburnt carbon (evident by TGA performance of UCCNA as in Fig. 2c) in UCCNA is the reason for the detachment between hydrated products and un-hydrated FFA at the age of 7 days. Because these unburnt carbons retard the reaction phase, which results in a porous structure. In the context of rheological properties of SCC, it was found to be advantageous, and it became an evident reason for the increment of slump flow properties of UCCNA-based SCC mixes in comparison with CCNA-based SCC mixes as discussed in Sect. 4.1 (refer Fig. 8).
Further observation of hydrated product at the age of 90 days revealed the presence of un-hydrated FFA in UCCNA prominent binders. It represents poor paste structure with less CSH (calcium silicate hydrate), CH (calcium hydroxide), and ettringite at the age of 90 days. It was evident for the reduction of mechanical properties of UCCNA-based SCC mixes. Simultaneously, more CH and ettringite formation was observed in OPC+FFA+UCCNA5  . 18m) and OPC+FFA+UCCNA10 (Fig. 18n) at the age of 90 days, which represents durability challenges of ternary paste [88]. Further, UCCNA prominent binders like (OPC+FFA+UCCNA15 (Fig. 18o) and OPC+FFA+UCCNA20 (Fig. 18p) represent more unhydrated FFA with a pore structure. However, in the context of CCNA prominent binders, dense structures with wellhydrated products of CSH, CH, and ettringite were observed at the age of 90 days. Overall, in comparison with all paste combinations, OPC+FFA+CCNA15 (Figs. 17i and 18s) were found to be dense with well-formed hydrated products at age of both 7 and 90 days of curing periods. Additionally, these findings are in line with the mechanical and rheological properties of SCC.

EDS examination of SCC binders
Energy-dispersive spectroscopy detailed analysis of OPC, binary, and ternary binders is presented in Table 5. Si, Al, and Ca are major identified elements. The increased UCCNA content in ternary binder decrement trend regards Ca and Si+Al was found; it might be due to the increase of unburnt carbon in overall UCCNA prominent ternary blends [58]. These findings are in line with SEM analysis, where detachment between hydrated products and unhydrated FFA was observed at the age of 7 days (Fig. 17). Further, with the context of CCNA, an increment of Ca and Si+Al with an increase of CCNA replacement percentage (up to 15%) was found. However, at OPC+FFA+CCNA20, decremental element constituents were identified (Ca and Si+Al). It revealed that reaction degree performance of CCNA with OPC and FFA was found to be optimal at 15%. Further replacement of CCNA reduced the reaction degree performance with OPC and FFA; it might be due to the appearance of imbalance regards to shape, texture, and presence of unburnt carbon in the form of agglomerates in CCNA [37,58], which resulted in decrement of Ca and Si+Al constituents. These findings were in agreement with identified dense structure as observed in SEM images at the age of 90 days (Fig. 18). Elements ratios like Ca/Si, Ca/(Si+Al), Si/Al, and Ca/ Al are having a strong relation with mechanical characteristics of SCC. Specifically, Ca/Si and Si/Al have proportional and inversely proportional relation with the compressive strength of SCC [37,89]. Figure 19 represents the relation of compressive strength versus element ratios. In the context of UCCNA, decremental compressive strength was proportional and inversely proportional to Ca/Si and Si/Al ratios, respectively. Further, with CCNA context, incremental compressive strength was proportional and inversely proportional to Ca/Si and Si/Al ratios, respectively. It was due to the incremental of additional CSH gels in the presence of CCNA up to 15% replacement. Besides, the maximum Ca/Si ratio of about 2.12 (at the age of 7 days) and 2.931 (at the age of 90 days) with minimal Si/Al ratio of about 2.102 (at the age of 7 days) and 2.955 (at the age of 90 days) was found for OPC+FFA+CCNA15. The discoveries of higher Ca/Si ratios and lower Si/Al ratios have been attributed to the formation of more CSH gel [37,90]. Simultaneously identified CSH gels by TGA and XRD examination are in line with EDS findings. Overall OPC+FFA+CCNA15 was found to be an optimal performed ternary combination. In addition, these findings are even in line with the mechanical properties of SCC. Simultaneously, identified CSH gels by TGA and XRD examination were in line with EDS findings. Overall OPC+FFA+CCNA15 was found to be an optimal performed ternary combination. In addition, these findings were in line with the mechanical properties of SCC.

TGA examination of SCC binders
Thermogravimetric was performed on OPC, binary (OPC + FFA), and ternary (as UCCNA and CCNA prominent) paste with a rated temperature of about 5 °C/min for 7 and 90 days of curing period as in Figs. 20 and 21. In the context of 7-day curing period (Fig. 20), Derive. weight (%) represents disturbance by having huge variation between 0.4 and − 1.2%, which represents a loose phase of paste structure. Simultaneously at 90-day curing period (Fig. 21), Derive. weight (%) represents minimal disturbance by having the least variation between − 0.016 and − 0.16%, which represents a dense phase of paste structure. These findings are well in agreement with the SEM characterization of paste. Initial loss of weight was found between 49-191 °C and 46-218 °C for 7-and 90-day curing period. In this, loss of H 2 O was due to dehydration of CSH as a major chemical component followed by carboaluminates and ettringite as a secondary chemical component [91,92]. The second major weight loss was observed between 332-441 °C and 353-468 °C for 7-and 90-day curing period. This major weight loss corresponds to the dehydroxylation of portlandite (CH) [93,94]. The third major weight loss was found between 575-674 °C and 583-700 °C for 7-and 90-day curing period. This huge loss corresponds to the decarbonization of calcium carbonate coming from the clinker and the filler [91,95]. Beyond 700 °C, weight loss was found to be neutral, because of the irreversible chemical component exhibited by the binder test subjects. In the context of UCCNA and CCNA ternary binders, major weight loss was observed in CCNA prioritized binders rather than UCCNA prioritized binders at the age of 7-and 90-day curing periods. CCNA was found to be more productive regards the production of CSH, CH, and ettringite which results in a denser structure rather than UCCNA prioritized binder.  Specifically, OPC+FFA+CCNA15 (weight loss of about 96-78% and 91-70% at the age of 7 and 90 days) was found to be in optimal combinations, which represent major weight loss regards 7-and 90-day curing period. These findings are in line with mechanical properties, XRD, and FTIR findings of SCC. OPC+FFA+UCCNA15 and OPC+FFA+UCCNA20 were found to be poor ternary combinations by gaining the least weight loss of about 99-87% and 95-75% at the age of 7 and 90 days. It confirms the presence of less quantified CSH, CH, and ettringite. Overall UCCNA replacement reduces the contribution of hydrated products in cement paste. Simultaneously CCNA replacement was found to be beneficial by contributing additional CSH gels. , and calcite (C) were found to be major phases regards all types of OPC, binary, and ternary pastes. Table 6 represents identified compounds and the chemical formulae of the same. Changes in peak heights and the formation of new peaks were identified through XRD analysis at the age of 90 days. The intensity of alite and belite was decreased and a new peak of clinotobermorite (CSH) was found at the age of 90 days (two thetas deg. 43 as in Fig. 23). Moreover, an increase in peak heights was observed regards ternary pastes validated the formation of intensified crystalline phase due to the addition of CCNA. Even these findings are in line with SEM, EDS, and TGA analysis. Further quantification of compounds was measured through XRD analysis and compared with compressive strength characteristics of concrete as in Fig. 24. The percentage quantification of these compounds was identified as a function of the paste phase, concentration, and the relationship between the intensity of the peak and the weight fraction. It was found that as the CSH quantification percentage increases, an increase regards compression strength was observed for CCNA prioritized binders. Meanwhile, with the decrease of CSH quantification percentage, a decrease regards compression strength was observed for UCCNA prioritized binders. The presence of more unburnt carbon in UCCNA was the cause for the reduction of clinotobermorite (CSH) gel resulting in poor structure. It is supported by TGA findings as in Figs. 20 and 21. Moreover, quantification of CSH, CH, CC, and E varies between 48-66%, 1-7.9%, 7-19.8%, and 15-34%, respectively. Observation of CH, CC, and E in comparison with compression strength was found to be insignificant. These findings is evident that the addition of CCNA was found to be advantageous, which implicates the dense structure. It was found that a maximum of up to 66% of CSH gels contributed to the formation of dense paste structures concerning the OPC+FFA+CCNA15 combination.

FTIR examination of SCC binders
Vibration frequencies of OPC, binary, and ternary pastes at the age of 7 and 90 days were measured by FTIR as in Fig. 25. Identifications give a sign of change in silicate, sulphate, hydroxide, and carbon phases. Silicate condensation reaction was observed through silicate infrared bands. Si-O bending (v 4 of SiO 4 ) was characteristically found at wavenumber 656 cm −1 [96,97]. Here sulphate chemistry displays very rapid crystallization followed by a slow recrystallization phase [98]. The percentage transmittance was found to be decreased for OPC, binary, and ternary pastes at the age of 90 days. The bending at 714 cm −1 , 877 cm −1 due to v 4 of CO 3 and v 2 of CO 3 was observed [99][100][101]. The development of a drop feature in the spectra at 800-970 cm −1 , qualified as the dissolution of C 3 S alite, correlates with the formation of CSH. The presence of a wide-ranging absorption hump between 995 and    [99].
Overall finding results reveal that densified paste structure was formed with regard to the CCNA prioritized binders in confidence with XRD, TGA, and SEM findings, and it was moreover contributed by the formation of additional CSH gels which purely depended on well-balanced ratios of sulphates and C 3 A+C 4 AF [98].

Drying shrinkage examination of SCC
Dr ying shr inkage per for mance on CM (base), TRCA-CA75-FA75-2 (to analyze the TRCA dominance), UCCNA and CCNA priority-based SCC mixes is presented in Fig. 26. Loss of water causes a change in length and volume due to self-desiccation and evaporation termed as shrinkage. The rate of shrinkage tends to be higher at the beginning of duration up to the age of 50 days and later stage shrinkage diminished. The magnitude of drying shrinkage was fewer regards UCCNA prioritized blends; simultaneously, a higher magnitude was found regards CCNA prioritized blends. The presence of more unburnt carbon in UCCNA reduces the rate of hydration and the overall degree of chemical reaction as confirmed by XRD, FTIR, TGA, SEM, and EDS findings. In addition, particle size distribution represents a coarser structure as in Fig. 2b than CCNA and FFA, which was the reason for less magnitude of drying shrinkage. Simultaneously, a higher degree of chemical reaction as confirmed by microstructural findings accelerates the hydration process, resulting in more demand regards to water, which promotes the higher magnitude of drying shrinkage. Besides the pozzolanic reaction of CCNA causes pore refinement that results in a greater rate of drying shrinkage [102]. Comparison of CM with TRCA-CA75-FA75-2 revealed that replacement of TRCA increases the water demand due to more WA characteristics of TRCA aggregate as confirmed in Fig. 7 resulting in more reduction regards concrete volume that results in greater drying shrinkage. Overall drying shrinkage was significantly increased due to CCNA and at the same; its behaviour was found to be vice-a-versa regards UCCNA prioritized blends.

Quality performance of SCC regards UPV, density, and water absorption
Performance evaluation through UPV represents modest characterization of SCC mixes by achieving velocity between 3121 and 3270 m/s. The compressive strength and density characteristics of SCC mixes were proportional to UPV performance. Simultaneously, WA characteristics of concrete were inversely proportional to UPV characteristics regards. TRCA, UCCNA, and CCNA prioritized SCC blends. It was found that as the increase of TRCA replacement percentage decreased regards compressive strength, UPV, and density were observed. TRCA and UCCNA prioritized SCC blends impart more microcracks, which results in poor UPV performances. Moreover, a decrease regard compressive strength and density were identified. However, concerning TRCA-CA75-FA75-1 and TRCA-CA75-FA75-2 improvements in compressive strength, density, and UPV performances were identified. It clarifies that BAGT with the restriction of 1.18 mm less sized fraction or so improves the SCC integral structure and was found to be advantageous. For that reason, an increase regards UPV performance of about 29 m/s was identified. Furthermore, CCNA prioritized SCC blends densified the mortar and it was evident by UPV, density, and compressive strength characteristics. Overall as per physical characteristics, it was found that replacement of 15% CCNA for the OPC was found to be optimal. Besides, quality assessment was in agreement with mechanical and microstructural findings (Fig. 27).

Carbon dioxide (CO 2 ) emissions
In the present study, CO 2 emission factors were analyzed by estimating the emission during the preparation of FFA, UCCNA, and CCNA, which include transportation, drying, grinding, calcination, and sieving process. Elaborated CO 2 emission factors of cementitious materials are presented in Table 7. Besides, Fig. 28 Table 8. Figure 29 represents the efficiency of SCC concerning compressive strength and CO2 emissions at the age of 7 and 90 days. Regarding the efficiency of SCC mixes, replacement of TRCA to natural aggregate was found to be inefficient, precisely while comparing TRCA-CA75-FA75-2 with CM found efficiency reduction of about 3.18% and 2.38% at the age of 7 and 90 days. Further, efficiency was increased due to the replacement of OPC by UCCNA and CCNA. Regarding UCCNA maximum efficiency was gained by TRCA-CA75-FA75-2-UCCNA10 and was about 4.76% in comparison with CM at the age of 90 days. Simultaneously, regarding CCNA, maximum efficiency was gained by TRCA-CA75-FA75-2-CCNA20 and was about 23.011% and 26.98% in comparison with CM at the age of 7 and 90 days. It was evident that utilizing CCNA as an OPC replacement was found to be more advantageous in regard to the performance of concrete efficiency.

Conclusions
The present study focused on analyzing the performance of CCNA and UCCNA prioritized ternary blends in TRCA incorporated SCC. The performance of SCC mixes was analyzed in detail through measured rheological and mechanical properties. Besides, the microstructural performance of OPC, binary, and ternary blends was examined through SEM, EDS, XRD, TGA, and FTIR tests. In addition, the quality and dynamic instability of SCC were examined through UPV and drying shrinkage examinations. Based on overall findings following conclusions were drawn.
• Material characterization of UCCNA reveals coarser structure as of OPC. Besides TGA, performance ensures the presence of more unburnt carbons, but still, oxide composition classifies UCCNA as a pozzolanic material. • Material characterization of CCNA reveals finer structure as of FFA, and oxide composition classifies CCNA as pozzolanic + cementitious material. • The adapted novel freezing-thawing cyclic procedure followed by Los Angeles abrasion treatment was found to be an advantage by reducing WA percentage by 9% (initial) to 2.94% and 3.91% regards TRCA coarse and fine. • Rheological properties are sensitive regards TRCA replacement percentage, and it significantly appears to be a reduced trend as the increase of TRCA replacement percentage. • Adaptation of BAGT with the restrict of TRCA-FA having particle size 1.18 mm or less was found to be advantageous regards slump flow characteristics, which enhance the relative slump flow performance by 3.27%.
• UCCNA prioritized SCC blends represent enhanced rheological performances up to 10% replacement percentage because the presence of more unburnt carbon retards the initial state of hydration. But at further replacement percentage which up to 20% rheological performance was diminished due to uncertain particle fraction as found by particle size distribution analysis of UCCNA, which coarser the overall ternary binder. • CCNA prioritized SCC blends represent diminished rheological performances because CCNA was a pozzolanic + cementitious material and it was in the calcined phase, which enhanced the initial state reaction, which results in an accelerated hydration process. • Compliance requirement of concrete analyzed through compression, flexural, and modulus of elasticity char-  acteristics, and it revealed about possible maximum replacement percentage was up to 75% regards both TRCA coarse and fine aggregates. • Mechanical characteristics of SCC decrease as the increase of replacement percentage regard the coarse and fines of TRCA. Besides BAGT was found to be a more suitable technique regards SCC mixes; specifically, restriction of 1.18 mm or less TRCA fraction through BAGT improves the relative performance of compressive, flexural, split, and modulus of elasticity strength by 19.11%, 31.12%, 32.15%, and 4.06%. • UCCNA prioritized SCC blends represent decremental mechanical performance; simultaneously, CCNA prioritized SCC blends represent incremental mechanical performance up to 15%. The presence of more unburnt carbon was the culprit for the poor performance regards UCCNA prioritized SCC blends, and it was revealed that to bring reaction phase, calcination of agro-waste was essential. • Microstructural findings regard SEM, EDS, XRD, TGA, and FTIR were in line with the rheological and mechanical performance of SCC mixes. It was found that 15% replacement of CCNA was optimal and UCCNA prioritized ternary blends represent poor reactive phase. • Dynamic instability was analyzed through drying shrinkage, and it revealed that UCCNA prioritized SCC blends found to be more stable by gaining fewer shrinkage characteristics in comparison with CCNA prioritized SCC. • Quality assessment of SCC through UPV represents dense structure regards CCNA prioritized SCC blends. Specifically, 15% of CCNA prioritized SCC represents fewer microcracks with the solidified integral structure of SCC. • In terms of CCNA, the maximum efficiency was achieved with TRCA-CA75-FA75-2-CCNA20 and was around 23.011% and 26.98% compared to CM at 7 and 90 days of age. • The lowest CO 2 emission rate of about 346.50 kg CO 2 / m 3 was found for TRCA-CA75-FA75-2-UCCNA20, and it was about a 19.41% reduction in comparison with CM.
Overall utilization of UCCNA in the ternary blend was found to be unscientific, and it appeared to be drawback regards mechanical characteristics of concrete. However, at the same instant regards dynamic instability UCCNA was found quite beneficial. However, UCCNA is not recommended to use as a binder for real-time practices. Besides CCNA is recommended to utilize as a supplementary cementitious binder, specifically TRCA-CA75-FA75-2-CCNA15 is recommended for the application of field condition practices.