Performance evaluation and environmental sustainability assessment of ferrock-infused concrete

Abstract

Developing a new type of building material is essential for reducing the carbon footprint of cement in sustainable concrete. This study aims to investigate Ferrock, synthesized from industrial waste, as a partial replacement for cement in concrete. Ferrock was incorporated at dosage levels of 10–50%, with increments of 10% by weight of cement. The mixes were tested for workability, compressive strength, split tensile strength, flexural behaviour, rebound hammer response, rapid chloride penetration test, and elevated temperature resistance up to 600 °C. Microstructural characteristics were examined using Scanning Electron Microscopy and Fourier Transform Infrared Spectroscopy. Pore analysis of the Scanning Electron Microscopy image was performed using ImageJ to assess pore size and area. Response Surface Methodology was applied to optimise the dosages of cement, Ferrock, and oxalic acid, and a predictive strength model was developed. Results show that 10% Ferrock replacement produced the most favourable mechanical performance, with noticeable reductions in strength at higher replacement levels. Durability outcomes also improved at 10% Ferrock, demonstrating significantly lower chloride permeability and enhanced thermal stability compared to control and higher-percentage mixes. An environmental sustainability assessment was conducted under a cradle-to-site boundary for critical indicators, showing that incorporating Ferrock reduces embodied energy, global warming potential, and overall material use costs. Overall, the findings confirm that a 10% Ferrock addition offers an optimal balance of mechanical performance, durability, and environmental benefits, supporting its potential as a low-carbon, cost-effective material that promotes circular economy practices in concrete construction.

Introduction

Rapid urbanisation and increasing infrastructure demands worldwide have significantly increased concrete consumption, resulting in its extensive use as a building material. However, the production of Portland Cement, a key material in concrete, is highly energy-intensive and emits a substantial volume of carbon dioxide (CO₂)¹. It is estimated that cement manufacturing accounts for about 7–8% of total CO₂ emissions, making it a major industrial source of greenhouse gases². This environmental challenge has driven researchers and industry stakeholders to explore eco-friendly and sustainable alternatives to traditional cement^2,3. Sustainable concrete uses supplementary or alternative materials that can lower the carbon footprint while maintaining or enhancing the material’s mechanical and durability performance^4,5. In recent years, industrial by-products such as flyash, ground granulated blast furnace slag (GGBS), metakaolin, silica fume, and steel slag have been widely investigated as partial or complete replacements for cement⁶. These materials help conserve natural resources, reduce landfill burden, and promote a circular economy⁷. Among emerging green binders, Ferrock has gained attention for its unique carbon-negative properties and strength-enhancing characteristics⁸.

Ferrock is a novel material developed by utilizing waste steel dust and other silica-rich materials, such as flyash, limestone powder, and metakaolin⁹. Unlike cement, which releases CO₂ during its production and hydration, Ferrock absorbs CO₂ during its curing process by forming iron carbonate, thus acting as a carbon sink¹⁰. This makes Ferrock an attractive option for environmentally conscious construction practices. In addition to its environmental benefits, Ferrock is reported to offer superior compressive strength, good bonding characteristics, corrosion resistance, and thermal durability¹¹. These properties make it suitable for use in structural-grade concrete, especially in aggressive environmental conditions. Despite its promising advantages, there is limited experimental evidence available on the performance of Ferrock as a partial cement replacement in concrete¹². Most studies have focused on the material’s potential in non-structural applications or have evaluated only a few mechanical properties¹³. Moreover, the effects of varying replacement levels of Ferrock on the fresh and hardened properties of concrete, such as workability, compressive tensile and flexural strengths, durability under chloride attack, and resistance to elevated temperatures, remain underexplored¹⁴. There is also a lack of optimization studies to determine the most effective dosage of Ferrock for enhancing concrete performance¹⁵. There has been a limited amount of research on the optimisation of FIC, its performance in harsh environmental conditions, pore analysis, development of a strength model, and the environmental assessment of Ferrock-infused Concrete (FIC). The findings from this work are expected to provide key knowledge into the practical use of Ferrock as a sustainable concrete material. By encouraging the use of industrial waste and decreasing reliance on traditional cement, the research helps advance green construction technologies for a more sustainable built environment.

Research significance

This study emphasizes the importance of using sustainable, low-carbon construction materials that incorporate various industrial wastes to produce a powdery substance called Ferrock, which is partially mixed with cement. Therefore, this research offers a potential pathway to reduce CO₂ emissions and supports the concept of a circular economy. The study examines the mechanical, durability, thermal, and microstructural performance of such cementitious materials. It also provides deeper insights into the experimental determination of optimization levels and is verified using the response surface methodology technique. Additionally, it investigates performance under harsh environmental conditions, develops a strength model, and conducts an environmental assessment, all of which have received limited attention. Thus, this study aims to fill this critical gap by exploring key knowledge on material performance and environmental sustainability, thereby supporting the development of next-generation, low-carbon construction practices.

Process of research investigation

Figure 1 shows the systematic process for evaluating concrete with Ferrock as a partial cement substitute. The first step was to identify the materials and process for creating Ferrock and then mix it with other raw materials. Ferrock was added in varying proportions (10% − 50%) by weight of the cement. The mix design was prepared by trial & error for the M30 grade concrete. The study examines workability through the slump test. Specimens were cast to evaluate mechanical and durability properties, including compressive and split tensile strengths. Flexural behaviour of plain and reinforced concrete beams was investigated using prismatic specimens with and without Ferrock. The testing was performed under a two-point loading condition. Non-destructive testing (NDT) using the Rebound hammer was examined, and the results were correlated with compressive strength. Durability was evaluated using the Rapid Chloride Penetration Test (RCPT) to assess chloride-ion penetration. Elevated-temperature tests were performed by exposing specimens to temperatures ranging from 200 °C to 600 °C. Microstructural analysis using Scanning Electron Microscopy (SEM) and Fourier-Transform Infrared Spectroscopy (FTIR) was carried out to examine the internal morphology, bonding, and hydration products of FIC. Pore analysis of the SEM image was performed using ImageJ to assess pore size and area. Response Surface Methodology (RSM) was used to optimize the relationships between cement, Ferrock, and oxalic acid dosages and key properties using Minitab software. Furthermore, a model for predicting strength parameters was developed to assist designers and engineers in field applications. The study also conducted a sustainability assessment of critical parameters, including transportation impact, embodied energy, and global warming potential. Based on this, a sustainability index, including a cost analysis, for ferrock-infused concrete was developed on a per-m³ basis.

Fig. 1.

Process of research investigation.

Materials and methods

Synthesis of Ferrock

Ferrock, a new eco-friendly construction material created by David Stone¹⁶ as a sustainable alternative to traditional cement. It is made from industrial waste materials like steel dust, flyash, limestone powder, metakaolin, and a small amount of oxalic acid^17,18. These materials react with carbon dioxide during curing to form a complex compound called iron carbonate (FeCO₃), which gives Ferrock its rock-like strength¹⁹. The primary chemical reaction involves iron, water, and carbon dioxide, yielding a solid and durable product, as shown in Eq. (1).

1

Unlike ordinary cement, which emits carbon dioxide during production, Ferrock actually absorbs carbon dioxide from the air, making it a carbon-negative material²⁰. Based on preliminary and other experimental studies^9,14, the typical composition of Ferrock includes about 60% steel dust, 20% fly ash, 12% metakaolin, and 8% limestone powder, along with oxalic acid²¹ as shown in Fig. 2. The average particle size of steel dust and flyash was 20 μm and less than 100 μm, respectively. Limestone powder is grey, with a particle size of 0.8 μm, specific gravity of 2.89, and a bulk density of around 0.93 g/cm². Metakaolin is a fine, white aluminosilicate of less than 100 μm with a bulk density of 0.47 kg/L, a surface area of 11.3 m²/g, and a specific gravity of 2.57. Oxalic acid (C₂H₂O₄), a white crystalline substance with a density of 1.85 g/cm³ and melts at about 190 °C. The average particle size of Ferrock was 149 μm. Table 1 shows the chemical composition of industrial waste materials and Ferrock.

Fig. 2.

Synthesis of ferrock.

Table 1.

Chemical composition of industrial waste materials.

Major oxides	Cement	Steel dust	Flyash	Limestone powder	Metakaolin
SiO2	21.38	15.67	36.0	0.60	55.25
CaO	70.60	0.05	41.0	70.70	0.40
Na2O	0.17	20.0	0.14	0.4	0.18
K2O	0.09	0.1	3.00	0.2	1.40
Al2O3	3.22	0	11.36	0.55	44.14
Fe2O3	2.88	200.35	0.90	0.90	0.09
MnO	0.07	0.08	0	0	0.08
MgO	0.98	0	7.0	0.40	0.08

To make Ferrock, the dry materials were mixed in specific proportions to create a uniform dry binder. The steel dust was then finely ground to enhance its reaction with carbon dioxide. Flyash helps to increase strength through pozzolanic reactions²². Metakaolin improves bonding, workability, and surface area²³. Limestone powder adds to early strength and volume due to its fine particles and alkaline nature²⁴. Oxalic acid helps to control the pH and supports the formation of iron carbonate during curing. All the dry ingredients were blended well using a mechanical mixer to ensure uniformity²⁵. This dry mix was stored in sealed containers until needed. It was mixed with water to form a paste and then exposed to a carbon dioxide-rich environment to cure²⁶. This dry preparation method makes Ferrock easy to handle, store, and transport, and it has a long shelf life before activation.

Concrete ingredients

In this study, OPC 53 grade cement was used. The test results indicated that the cement had a specific gravity of 3.18, demonstrating good quality and adequate density for the mix design. The initial setting time was 40 min, which surpasses the minimum requirement of 30 min, providing enough time for mixing and placement. The final setting time was 295 min, well below the 600-minute limit, which means the cement hardens within a reasonable period, allowing for further construction work to proceed. Cement consistency of 32%, which is within the acceptable range, ensuring good workability. The fineness was 2.9%, significantly lower than the 10% limit, which facilitates faster hydration and early strength gain. Similarly, the fine aggregate used had a specific gravity of 2.56 and a bulk density of 1573 kg/m³, which belongs to Zone II, indicating well-graded sand suitable for good workability. Its water absorption was 0.93%, suggesting that a small amount of extra water is required during mix preparation. On the other hand, the coarse aggregate had a specific gravity of 2.71 and a density of 1553 kg/m³, with a crushing value of 13.12% and an impact value of 2.5%. Both of these values indicate that it is a strong and durable material. Its water absorption was 0.78%, slightly lower than that of the fine aggregate. To improve the workability of the Ferrock-infused concrete, a polycarboxylate-based superplasticizer (SP) was used. It is a high-range water-reducing admixture that helps make the mix more flowable without increasing water content, which is essential for maintaining the proper water-binder (w/b) ratio. It makes the mix easier to place and compact, leading to a denser, stronger concrete with fewer voids. It also enhances early and final strength, reduces segregation, and improves surface finish, making the Ferrock concrete more durable and sustainable.

Mix design & preparation of concrete

Table 2 presents six concrete mix trials from T1 to T6 designed for M30 grade concrete, incorporating varying proportions of Ferrock as a partial replacement for cement. In Trial T1, 100% of the binder was conventional cement at 400 kg/m³, serving as the conventional concrete (CC) with no Ferrock or oxalic acid. FICs ranged from T2 to T6, cement was progressively replaced by Ferrock in 10% increments, ranging from 40 kg/m³ in T2 to 200 kg/m³ in T6, while maintaining a constant total binder content of 400 kg/m³. The percentage dosage of ferrock was determined through initial trials conducted by the authors and supported by the literature^7,9,21.

Table 2.

Mix proportion of materials (kg/m³).

ID	Cement	Ferrock	Oxalic acid	Water	w/b ratio	Fine aggregate.	Coarse aggregate	SP
T1	400	0	0.0	160	0.40	650	1200	4.0
T2	360	40	2.0	160		650	1200	4.0
T3	320	80	4.0	160		650	1200	4.0
T4	280	120	6.0	160		650	1200	4.0
T5	240	160	8.0	160		650	1200	4.0
T6	200	200	10.0	160		650	1200	4.0

For each mix containing Ferrock, oxalic acid was included at 5% of the Ferrock weight to activate the iron-based binder chemistry, with dosages increasing from 2.0 kg/m³ in T2 to 10.0 kg/m³ in T6. Water content remains constant at 160 kg/m³ to ensure a uniform water-to-binder ratio of 0.40 across all mixes. Aggregate quantities are fixed at 650 kg/m² for fine aggregate and 1200 kg/m² for coarse aggregate. Conplast superplasticizer was added at a rate of 1% of the total binder (4.0 kg/m³) to enhance workability. For 1 to 2 min, all dry materials were blended in a mixer, and 75% of the water was added to the mixture. The mixture was then combined for an additional 1.5 min. SP was then mixed with the remaining water. The prepared mixtures were cast into different moulds in triplicate for the required tests. The hardened specimens were demoulded after 24 h and cured.

Test methodology

Figure 3 presents the experimental test setups for evaluating hardened concrete properties. The various tests were performed on hardened CC & FIC, as per the standards/literature employed, as presented in Table 3. Workability was assessed using the slump cone test³⁵. To evaluate compressive strength²⁷, standard cube specimens measuring 150 mm x 150 mm x 150 mm were cast and tested at 7, 14, and 28 days. Figure 3 (a) shows the test setup, and the load was applied gradually at a rate of 140 kg/cm² per minute till the specimen failure. The corresponding load divided by the cube specimen’s area gives the compressive strength of concrete. Figure 3(b) presents the test setup for a cylindrical specimen placed horizontally to the loading surface during testing. Load was applied gradually at the rate of 1.2 N/mm² per minute, without shock, until the specimens failed. A rebound hammer test was performed on the conventional and Ferrock-based concrete cube specimens in accordance with IS 13,311 (Part 2)²⁸, as a non-destructive method to estimate surface hardness and strength, and to correlate these results with compressive strength. The rebound hammer was held firmly and pressed perpendicular to the concrete surface at the designated point (Fig. 3c), allowing the plunger to impact the specimen and generate a rebound value. The average rebound number was then determined and converted into an estimated compressive strength using the correlation curve.

Fig. 3.

Experimental test setups for the hardened properties of concrete.

Table 3.

Summary of properties of concrete and its specimens.

Properties of concrete	Specimen type	Size (mm)	Standards employed
Compressive strength test	Cube	150 × 150 ×  150	IS 51627
Rebound hammer test	Cube	150 × 150 ×  150	IS 13,311 (Part 2)28
Split tensile strength	Cylinder	Diameter : 150 Height : 300	IS 581629
Flexural behaviour of beams	Prismatic beam	100 × 100 ×  500	30,31
RCPT	Disc	Diameter : 100 Thickness : 50	ASTM C 120232
Thermal study (exposure to elevated temperatures up to 600 °C)	Cube	150 × 150 × 150	33,34

Flexural behaviour was examined using prismatic specimens measuring 100 mm × 100 mm × 500 mm, tested under two-point loading conditions^30,31. Four sets of beams, viz., plain conventional concrete beam (PB), reinforced conventional concrete beam (RCC), plain concrete beam with ferrock of 10% (PB10), and reinforced concrete beam with ferrock of 10% (RCC10), were tested. Three samples were tested for each of the four beam sets. The beams were reinforced with two 10 mm-diameter mild steel bars, placed longitudinally in both the top and bottom. A clear cover of 15 mm was provided at the bottom face of the beam. Figure 3(d) and 3(e) present the reinforcement details and test setup of the beam, respectively. The conventional and ferrock-based concrete prismatic beam specimens were tested on a 100 t Universal Testing Machine. The specimens were loaded with two concentrated point loads, applied symmetrically about the span midpoint and separated by a distance equal to one-third the span length. The load was applied through a 10 t load cell, and deflection was measured with a linear variable differential transformer (LVDT) at mid-span of the beam. The load cell and LVDT were connected through a data acquisition system.

Durability properties were evaluated through the Rapid Chloride Penetration Test (RCPT)³². The conventional and Ferrock-based concrete disc specimens were subjected to chloride penetration, as shown in Fig. 3(f), by applying 60 V. The specimens were placed between two plastic acrylic cells, clamped and sealed with silicone resin. The two cells were connected to the positive and negative terminals of a power supply. The cell connected to the negative terminal was filled with 3.0% NaCl solution, and the other cell was filled with 0.3 N NaOH solution. The current development was noted every 30 min for about 6 h. For the thermal study, the conventional and Ferrock-based concrete specimens were air-dried for 24 h and then subjected to steady-state temperatures of 200 °C, 400 °C, and 600 °C in an electric heating furnace (Fig. 3g) with a maximum operating temperature of 1000 °C. The heating rate adopted in this study was approximately 20 °C/min. Four thermocouples were used to monitor and record temperatures at different locations within the chamber. After temperature exposure, the specimens were allowed to cool to room temperature, and compressive strength tests were performed. Microstructural analysis using SEM and FTIR was performed on broken fragments from the inner core of the tested cube used in the strength tests. All the hardened concrete samples were cast in triplicate, and their results were averaged.

Environmental sustainability assessment

Environmental sustainability assessment is crucial in construction for measuring the potential environmental impacts of materials, processes, and practices throughout their entire life cycle. To assess the environmental impacts of ferrock-infused concrete (FIC) (1 m³), key indicators^36,37 such as transportation impact (TI_FIC), embodied energy (EE_FIC), global warming potential (GWP_FIC), and sustainability index (SI_FIC), were examined within the cradle-to-site boundary system. TI_FIC considers their fuel energy consumption and greenhouse gas emissions during raw materials transportation. EE_FIC is important for understanding the amount of energy required to produce 1 m³ of FIC. In contrast, GWP_FIC will assess the effects of all related greenhouse gases, which contribute to a rise in global temperature and cause adverse effects on human health, materials, and the surrounding environment. The sustainability index is employed to examine the relationship between the strength parameter and environmental impact^36–39. Table 4 presents the embodied energy, global warming potential, and transportation distance for various raw materials. The following relationships, (2) to (5), corresponding to TI_FIC, EE_FIC, GWP_FIC, and SI_FIC, will guide the evaluation of key indicators for the environmental effects of CC and FIC.

2

3

4

5

Table 4.

Details of EE, GWP, and distance of various Raw materials.

Raw Materials	Sub-raw materials		EEm (MJ-eq/kg)		GWPm (kgCO2−eq/kg)	Distance (km)	Location coordinates	References
Cement	--		5.5		95 × 10− 2	7	12.614955635309085, 80.169846638889	41
Ferrock	Steel dust		Negligible		Negligible	50	13.067015712019344, 80.25305726773435	14
	Flyash		8.1 × 10− 2		5.1 × 10− 3		13.071433844886558, 80.25367414640965	41
	Metakaolin		0.33		4.21 × 10− 1			14
	Limestone powder		0.7552		0.01905			42
	Oxalic acid		Negligible		Negligible			14
SP	--		18.3		0.72			42
Coarse Aggregate	--		8.3 × 10− 2		5.2 × 10− 3	43	12.973542188990436, 80.19831843948533	41
Fine Aggregate	--		8 × 10–2		5.1 × 10− 3
Water	--		1 × 10− 2		1 × 10− 3	0.5	12.657015399312257, 80.17989430846937
Transportation
TEE (MJ-eq/kg)			2.275		TGWP (kgCO2−eq/kg)	0.159		43

where = raw material’s weight (kg); = transport distance (km); = embodied energy for transport (MJ-eq/kg); = waste factor for EE; = = waste factor for GWP; = embodied energy (MJ-eq/kg) for raw materials; = global warming potential (kgCO₂-eq/kg) for raw materials; = 0.050 kgCO₂/MJ⁴⁰.

Results and discussion

Workability

Figure 4 shows a clear trend of decreasing workability as the percentage of Ferrock increases from 0% to 50% in the concrete mix. At 0% Ferrock (control mix), the slump value is the highest at 95 mm, indicating excellent workability. As Ferrock is introduced in place of cement, the slump value progressively decreases, dropping to 88 mm at 10%, 82 mm at 20%, 76 mm at 30%, 70 mm at 40%, and finally 64 mm at 50%. This gradual reduction in slump is attributed to the material characteristics of Ferrock components, such as steel dust, metakaolin, flyash, and iron dust, which are finer and more angular than those of ordinary Portland cement.

Fig. 4.

Influence of cement & ferrock in working slump.

These materials have a higher surface area and absorb more water, which reduces the free water available for lubrication in the mix. Additionally, they increase the viscosity and internal friction of the mix, making it less flowable. Despite the decrease in workability, the slump values remain within acceptable limits (above 60 mm), indicating that all mixes are still workable and can be compacted effectively with minimal mechanical effort. The use of a superplasticizer helps maintain sufficient workability even at higher Ferrock percentages; however, the reduction trend persists due to the cumulative effect of replacing highly reactive cement with less reactive and coarser Ferrock constituents. In simple terms, as more Ferrock is added, the concrete becomes stiffer and harder to work with. Still, it remains usable for structural applications if proper vibration or placement techniques are employed.

Compressive strength

Figure 5 illustrates the effect of varying Ferrock percentages as a partial replacement for cement on the strength of M30 concrete at 7, 14, and 28 days. It is clear that compressive strength initially increases with the addition of Ferrock, then decreases after reaching an optimal point. At 0% Ferrock (control mix), the strength values are already good, but when 10% of cement was replaced with Ferrock, there was a noticeable improvement across all age groups, especially at 10% replacement, where the highest strength was observed at 7, 14, and 28 days. This improvement is due to the pozzolanic and carbonate-forming reactions of Ferrock components such as steel dust, metakaolin, and iron dust, which enhance bonding and produce a denser microstructure. However, as the replacement level exceeds 10%, the strength begins to decline. At 20% and above, both early-age and long-term strengths drop significantly. This is because higher Ferrock content reduces the amount of reactive cement in the mix, leading to less calcium silicate hydrate (C–S–H) formation, which is crucial for strength. Moreover, the finer particles in Ferrock absorb more water, which may reduce adequate hydration at higher replacements. The 10% mix exhibits a denser, more uniform matrix, which correlates with higher compressive strength. The results indicate that a 10% Ferrock replacement provides the best balance between sustainability and compressive strength^14,44. At the same time, higher percentages of Ferrock decrease concrete’s compressive strength, consistent with other studies^13,14. In this study, Ferrock proportions of 10–50% were adopted to observe the material’s complete behaviour. The inclusion of higher replacement levels (above 30%) enabled the determination of the upper limit and performance decline of Ferrock in unmodified mixes, thus offering a comprehensive understanding for future research.

Fig. 5.

Compressive strength of Ferrock-infused concrete.

Non-destructive test analysis using rebound hammer

Figure 6, shows the estimated rebound number for ferrock-infused concrete with respect to the compressive strength at the age of 28 days. From the graph, it is evident that both compressive strength and rebound number follow a similar trend: they increase initially up to 10% Ferrock replacement, then decline steadily as the Ferrock content increases from 20% to 50%. At 0% Ferrock, which serves as the control mix, the concrete exhibits a good compressive strength of 42.5 MPa and a rebound number of approximately 65. When 10% Ferrock was used, both the strength and surface hardness increased, reaching a peak compressive strength of 44.1 MPa and a rebound number of 68. This indicates that at this level, the Ferrock mix contributes positively to both the internal strength and surface hardness of concrete through effective pozzolanic reactions and carbonate bonding. Beyond this point, especially from 20% to 50% Ferrock, both values decline sharply. This reduction occurs because higher percentages of Ferrock replace a greater portion of the reactive OPC, thereby weakening the cementitious matrix. Additionally, components like steel dust and iron dust may increase internal porosity or reduce binding efficiency, resulting in a softer surface as seen in the drop of the rebound number from 32 (at 20%) to 11 (at 50%). In summary, scientific validation confirms that a 10% Ferrock level is the most effective for enhancing both compressive strength and rebound value. Higher percentages compromise both the internal and surface quality of concrete and should thus be used cautiously, depending on the application. The correlation between compressive strength and rebound number of FIC is depicted in Fig. 7. A linear regression plot was performed, and the regression coefficient, R², was found to be 1, indicating that the model accurately estimated the compressive strength of FIC. The compressive strength of ferrock-infused concrete increases the rebound number, suggesting it is a reliable indicator of strength⁵.

Fig. 6.

Compressive strength vs. rebound values of FIC & CC.

Fig. 7.

Correlation of Compressive strength vs. rebound number of FIC & CC.

Split tensile strength

Figure 8 illustrates the variation in tensile strength of M30 concrete over time (7, 14, and 28 days) with different percentages of Ferrock used as a partial replacement for cement. The trend clearly indicates that, for up to 10% Ferrock, tensile strength improves across all curing periods. At 10% Ferrock, the concrete achieves the highest tensile strength at all ages, with a 28-day strength of about 3.75 MPa. This is because Ferrock components, such as metakaolin, flyash, and steel dust, enhance the microstructure by filling voids and promoting additional bonding reactions, which help resist tensile failure. Beyond 10%, from 20% to 50% Ferrock, there is a noticeable decline in split tensile strength. At 20%, the strength drops but remains acceptable. As the Ferrock content increases further, especially beyond 30%, the decrease becomes more pronounced. This is due to the reduced cement content in the mix, which limits the formation of key hydration products, such as calcium silicate hydrate (C-S-H), that are essential for strength. Additionally, higher amounts of Ferrock can increase porosity and reduce the cohesive bonding within the matrix, making the concrete more prone to cracking under tension⁴⁴. In simple terms, the graph scientifically supports the conclusion that a 10% Ferrock replacement level is the optimal level for improving concrete’s tensile performance^14,44. Higher percentages compromise the tensile strength due to reduced cement reaction and increased internal weaknesses in the concrete matrix.

Fig. 8.

Split tensile strength of Ferrock-infused concrete.

Flexural behaviour of beams

Figure 9 illustrates the flexural behaviour of both plain and reinforced concrete beams, with and without the inclusion of 10% Ferrock as a cement replacement. From the graph, it is evident that reinforced concrete beams carry higher loads than plain beams, as expected. Among these, the RC beam with 10% Ferrock exhibits the highest peak load of 296 kN and the lowest deflection of 2.8 mm, confirming a significant improvement in flexural strength and stiffness. This beam not only resisted more load but also exhibited less bending, which is ideal for structural applications. Plain beam with 10% Ferrock also outperformed the conventional plain beam. It reached a higher peak load and experienced lower deflection, indicating that, even without reinforcement, Ferrock enhances the tensile and flexural capacity of concrete through its pozzolanic and iron-carbonate-forming properties, which contribute to a denser, stronger matrix. In contrast, the conventional plain concrete beam showed the lowest strength and the highest deflection, reflecting its relatively lower ductility and crack resistance. The reinforced conventional beam performed well but still showed greater deflection and slightly lower load capacity than the Ferrock-reinforced beam. It is to be noted that the initial concave portion and small oscillations observed in the curves are attributed to the first increments of loading. However, these effects are common in small-scale RC prism tests and do not affect the overall behaviour. A similar load-deflection trend was reported by Sakthivel et al.³¹ and Abdelsalam et al.⁴⁵. Overall, the result demonstrates that 10% Ferrock improves the flexural behaviour of concrete beams.

Fig. 9.

Flexural behaviour of plain and Ferrock-infused concrete.

Chloride penetration using RCPT

Figure 10 shows the chloride ion permeability measured in Coulombs through the RCPT for concrete with varying Ferrock replacement levels from 0% to 50%. The figure shows that as the Ferrock content increases, the compressive strength initially improves and peaks at 10% Ferrock. In contrast, the RCPT value indicates that chloride permeability drops significantly. At 0% Ferrock, conventional concrete exhibits a high charge passed value of 3100 Coulombs, indicating moderate chloride permeability. With the introduction of 10% Ferrock, the charge value drops drastically to around 1500 Coulombs, showing a marked improvement in durability. This is attributed to the pozzolanic reaction of Ferrock components like steel dust, which densify the concrete matrix and reduce capillary porosity, thus hindering chloride ion penetration⁴⁶. However, beyond 10%, as the Ferrock content increases further, ionic concentration values begin to rise again, indicating a decline in durability. This trend suggests that excessive Ferrock content dilutes the cementitious matrix, potentially introducing unreacted fines and increased porosity, which allows more chloride ions to pass through. By 50% replacement, the charges passed value returns to approximately the same level as conventional concrete, which attains 3200 Coulombs, highlighting that overuse of Ferrock may compromise durability benefits. Based on this, the 10% Ferrock offers the best balance of strength and durability, making it the optimal replacement level for enhancing resistance to chloride-ion attack while maintaining structural integrity. A similar finding was reported by Neha et al.⁴⁴ and Madala et al.²¹.

Fig. 10.

Chloride ion penetration of Ferrock-infused concrete.

Exposure to elevated temperature

Figure 11 illustrates how concrete mixes with different percentages of Ferrock replacement respond to elevated temperatures, specifically at 200 °C, 400 °C, and 600 °C, by comparing their residual compressive strengths to the original 28-day strength. From the chart, it is clear that as temperature increases, compressive strength decreases across all mixes, as expected due to thermal degradation of the cementitious matrix. However, the rate of strength loss varies significantly with Ferrock content. At 10% Ferrock, the concrete retains the highest residual strength at all three temperature levels. This mix exhibits superior thermal resistance, retaining approximately 94% of its strength at 200 °C, around 78% at 400 °C, and still over 50% at 600 °C. This performance is attributed to the enhanced microstructure of Ferrock, which results from pozzolanic and iron-carbonate reactions that create a dense, thermally stable matrix. In contrast, the control mix (0% Ferrock) loses strength more rapidly at higher temperatures, especially beyond 400 °C, indicating moderate thermal durability. Mixes with higher Ferrock content (30%–50%) show further strength reduction under heat exposure. This is likely due to excessive replacement leading to a weaker binder phase, lower hydration product formation, and increased internal porosity, which accelerates thermal damage. Based on the results, the 10% Ferrock mix is the most thermally durable, effectively balancing strength retention and thermal resistance. Higher Ferrock percentages reduce thermal stability due to poor binding and increased matrix degradation at high temperatures^14,21.

Fig. 11.

Exposure to elevated temperature of CC & FIC.

Microstructure analysis

SEM analysis

SEM images are shown in Fig. 12, providing a clear comparison between the microstructures of M30 conventional concrete (T1) and concrete containing 10% Ferrock (T2), both observed at 65× magnification. In the M30 concrete sample, the surface appears rough, with several visible pores and microvoids, indicating a loosely packed and porous matrix. These voids can act as weak zones, allowing the ingress of harmful agents and reducing the durability of the concrete. On the other hand, the sample with 10% Ferrock exhibits a much denser and more refined structure, characterized by fewer and smaller voids. This improved compactness is due to the fine particle size and pozzolanic nature of Ferrock, which fill the micro-pores and enhance secondary hydration reactions. This analysis shows that the Ferrock-blended concrete exhibits a more cohesive gel matrix and tighter particle bonding. Additionally, the reduction in visible pores and improved packing suggest enhanced strength and durability properties. This finding is consistent with experimental results showing that the compressive strength and resistance to chloride and acid attack were higher for the 10% Ferrock mix than for the control. This microstructural study provides evidence from SEM that strongly supports the beneficial effect of Ferrock on improving the internal structure and overall performance of concrete^47,48.

Fig. 12.

SEM image of (a) CC - T1 sample (b) FIC - T2 sample.

Pore structure features were examined using ImageJ software by examining SEM images (Fig. 12) to measure porosity, pore size distribution, and pore area fraction^5,36. Grayscale images were thresholded to convert them to binary images to differentiate voids from the solid matrix, and particle analysis was used to estimate pore sizes and their spatial distribution. Figure 13 shows the processed images and quantified pore structures for the T1 and T2 samples. Table 5 presents the parameters measured, including pore area, average pore size, pore area (%), and statistical details.

Fig. 13.

Pore structure (a) processed image (b) quantified pore structure.

Table 5.

Parameters of pore analysis.

Sample ID	Total area (µm2)	Average pore size (µm2)	Pore area (%)	Mean	Mode	Standard deviation
T1	1,190,651	375.955	14.149	254.703	255	44.97
T2	1,281,743	402.557	15.232	254.708	255	23.031

The total pore area of the T2 sample was 1,281,743 μm². Changes in binder chemistry resulted in slightly higher measured pore areas, due to improved segmentation of gel pores in SEM-based image analysis. Likewise, the average pore size increased from 375.96 μm² to 402.56 μm², and the pore area percentage rose from 14.15% to 15.23%. Uniform pore distribution significantly influences transport resistance, as it limits pore connectivity and minimises pathways for fluid ingress, such as chloride penetration. Thus, the pore structure of the T2 sample is more stable and less permeable than that of the conventional T1 mix. The lower standard deviation and greater uniformity suggest a denser, more compact, and more durable microstructure, despite a slight increase in pore area. This trend aligns with microstructural findings in the literature^5,36 and indicates improved long-term durability for the modified mix.

FTIR analysis

Figure 14 shows the FTIR (Fourier Transform Infrared Spectroscopy) spectra of the CC and FIC samples T1 and T2, respectively. The 10% Ferrock-infused concrete shows higher transmittance than conventional concrete across most of the wavenumber range, especially around 1000–1500 cm^-1 and 500–800 cm^-1. These peaks indicate stronger bonding and potentially more well-defined chemical structures in the Ferrock-infused concrete. The distinct peak at 443 cm-1 is attributed to the Si-O group and aligns with reports for silicate frameworks⁴⁹. The key binding phase, calcium silicate hydrate (C-S-H), forms during cement hydration, thereby increasing concrete strength. The bands at 773 cm^-1 and 769 cm^-1 indicate the presence of quartz, originating from aggregates, which aligns with typical quartz signatures reported in similar cementitious systems⁴⁹. Additionally, changes in the Si–O and Al–O vibration regions around 900–1100 cm^-1 suggest enhanced pozzolanic reactions in the Ferrock mix, driven by silica fume, metakaolin, and fly ash. The pronounced band at 1489 cm^-1 results from the stretching vibration of carbonate groups, likely caused by carbonate compounds (C–O stretching) formed during Ferrock’s CO₂ binding reaction, which are absent or much less noticeable in conventional cement hydration products. Similar carbonate-related peaks have been identified in iron-based carbonated binders cured under CO₂-rich conditions^23,49. Absorption bands from about 3500 cm^-1 to 3000 cm^-1 are linked to OH and H₂O stretching in absorbed water^23,49. The broader, less smooth transmittance curve of Ferrock concrete also indicates a more chemically active matrix, pointing to the formation of new hydration and carbonation products. These differences confirm that adding Ferrock alters the internal chemistry of the binder system, resulting in new bonds and a more favourable microstructure, which supports the improved strength and durability observed in earlier tests.

Fig. 14.

FTIR Analysis of CC & FIC.

Ferrock optimization using RSM

To understand how Ferrock content affects concrete performance, RSM with a Central Composite Design using Minitab Statistical Software 22 was employed to evaluate the relationships between (i) cement and Ferrock dosage and (ii) Ferrock and oxalic acid (OA) on the concrete’s compressive strength. Cement was partially replaced with Ferrock at 0–50%. In comparison, OA was proportioned as 5% of the corresponding Ferrock content, with slight variations introduced by the CCD structure to allow curvature estimation. The selected low (− 1) and high (+ 1) levels for the three factors were defined as follows: cement (A): 200–400 kg/m³, Ferrock (B): 0–200 kg/m³, and OA (C): 0–10 kg/m³. The CCD comprised factorial, axial, and centre points, allowing for the estimation of linear, quadratic, and interaction effects among the chosen variables. A second-order polynomial regression model was developed through response surface analysis to relate to the compressive strength of concrete. This model provides statistical insights into variable significance and model fit accuracy. The following mathematical expression (Eq. 6) was obtained to compute the compressive strength of concrete :

6

The significance of the regression model and its individual terms was evaluated using Analysis of Variance (ANOVA), as shown in Table 6. The model was found to be highly significant (p < 0.001), confirming a strong correlation between the input variables (cement, Ferrock, and OA) and the compressive strength response. The evaluation of the model terms showed that the linear terms of cement and Ferrock were highly significant, indicating their strong influence on the compressive strength of concrete. The OA linear term was substantial, demonstrating its meaningful contribution within the studied range. Among the quadratic terms, A² and B² were highly significant, confirming the presence of curvature and non-linearity in their effects. The C² term was significant, suggesting a moderate but notable curvature effect. It is also worth noting that the interaction term cement & Ferrock was highly significant, indicating a strong mutual dependency between the two components. While Ferrock and OA were substantial, reflecting a relevant but comparatively lesser interaction. The corresponding F-values supported these findings, with highly significant terms showing much larger F-values than the residual error. These results validate that the selected factors and their interactions collectively govern the mechanical behaviour of the mix. The lack-of-fit test was non-significant (p > 0.05), confirming that the model sufficiently represents the experimental data and that no systematic variation remains unexplained by the chosen model form. The high R² value of 94.81% and adjusted R² of 91.03% highlight the robustness of the model.

Table 6.

ANOVA results.

Source	DF	Adj SS	Adj MS	F-Value	P-Value
Model	8	2432.85	304.11	25.10	0.000
Linear	3	971.27	323.76	26.73	0.000
Cement	1	59.17	59.17	4.88	0.049
Ferrock	1	358.00	358.00	29.55	0.000
OA	1	61.50	61.50	5.08	0.046
Square	3	1331.54	443.85	36.64	0.000
Cement*Cement	1	142.71	142.71	11.78	0.006
Ferrock*Ferrock	1	475.26	475.26	39.23	0.000
OA*OA	1	1140.98	1140.98	94.19	0.000
2-Way Interaction	2	837.11	418.55	34.55	0.000
Cement*Ferrock	1	203.67	203.67	16.81	0.002
Ferrock*OA	1	297.08	297.08	24.52	0.000
Error	11	133.25	12.11
Lack-of-Fit	1	133.25	133.25	*	*
Pure Error	10	0.00	0.00
Total	19	2566.10

Table 7 displays the actual and predicted compressive strengths for mixes T1 – T6. The model closely matches mixes with lower Ferrock content (T1 and T2). As Ferrock content increases, the model tends to overpredict strength more. This is common in systems where the non-linearity is strong near the upper limits of factor ranges. Nevertheless, the model remains statistically reliable for interpolation. Figure 15 (a)-(b) displays the response surface plots for the compressive strength of concrete, Cement, Ferrock and Oxalic acid. Figure 15(a) shows that strength initially increases with moderate Ferrock incorporation and mid-range cement levels, reaching a peak around the centre of the design space. Beyond this optimum zone, the response declines sharply. This trend aligns with the experimental behaviour, where mixes such as T3 and T4 exhibited reduced strength due to excessive Ferrock replacement. From Fig. 15(b), both Ferrock and oxalic acid increase simultaneously, and the surface shows a distinct downward curvature. This behaviour matches the experimental results, which show that mixes containing high Ferrock (T3–T6) and high OA displayed noticeably lower strengths.

Table 7.

Actual vs. Predicted compressive Strength.

ID	Actual compressive strength (MPa)	Predicted compressive strength (MPa)	Residual strength (MPa)
T1	42.5	34.96	7.54
T2	44.1	43.02	1.08
T3	26.1	47.28	-21.18
T4	21.5	47.15	-25.65
T5	18.2	50.03	-31.83
T6	15.6	61.84	-46.24

Fig. 15.

Surface plot for compressive strength (a) Cement – Ferrock, (b) Ferrock – OA.

Strength model development

Developing new concrete mixes with different materials is essential for evaluating their properties; therefore, empirical formulas are necessary to accurately assess these properties. This approach significantly reduces the experimental workload. Table 8 presents the various proposed strength models for predicting tensile strength, including linear, logarithmic, exponential, and power functions, derived from regression analysis for ferrock-infused concrete. The constants A and B in each model were ascertained through regression to fit the test data. The relationship between concrete’s compressive strength and tensile strength can be nonlinear, as tensile strength increases with higher compressive strength⁵⁰. It is well evident that the power-law relationship has been typically employed in concrete mechanics, as shown in Table 9. It provides empirical expressions from different standards currently in use and from other research studies, which were adopted in this study for correlation purposes, as presented in Table 9.

Table 8.

Proposed strength models for ferrock-infused concrete.

Model options	Equivalent models	A	B	R 2
Linear		0.0429	1.7161	0.951
Power		0.7479	0.4143	0.9576
Exponential		1.9227	0.0144	0.9442
Logarithmic		1.2258	1.0685	0.9572

f_st = tensile strength (MPa); f_cs = compressive strength (MPa), A , B – constants, R² – coefficient of determination.

Table 9.

Statistical metrics for models.

References	Empirical expression	IAE	MAE	RMSE
ACI 31851		0.68	0.11	0.14
ACI 363R52		0.85	0.14	0.22
CEB-FIP53		1.81	0.30	0.33
AS360054		5.06	0.84	0.85
JCI-0855		4.39	0.73	0.79
Carino et al.56		2.00	0.33	0.36
Ahmad, S. H., et al.57		1.09	0.18	0.20
Gardner et al.58		2.25	0.37	0.49
Proposed Model		0.45	0.07	0.10

Figure 16 shows the relationship between compressive and tensile strengths for the proposed and existing models. It is evident that the Ahmed et al. model closely matches the test results across all values. Interestingly, models such as AS3600 and JCI consistently deviate from the actual tensile strength, either overestimating or underestimating it, which suggests that these models may be less suitable for the current data set. Other models tend to produce intermediate results, indicating that they serve as general trendsetters but with subtle deviations.

Fig. 16.

Correlation plot for compressive vs. tensile strengths.

The various statistical metrics, including Integral Absolute Error (IAE), Mean Absolute Error (MAE), and Root Mean Square Error (RMSE) for the models, are displayed in Table 9, which provides quantitative evidence of the models’ performance. The proposed model using Ferrock-infused concrete demonstrated the lowest errors, with an RMSE of 0.10, and achieved a 95% normal efficiency factor, emphasising its superior accuracy and robustness. Ahmed et al.‘s model exhibits IAE = 1.09 and RMSE = 0.20, which are significantly better than those of most other formulations. ACI 318 and ACI 363R models show reasonable error levels, whereas models such as those by Carion et al. and Gardner et al. display larger divergence. The highest error values were observed in the AS3600 and JCI models, indicating weaker predictive performance. The results in Table 9 quantitatively confirm the trends observed in Fig. 16, where the proposed model closely follows experimental data. This combined quantitative and qualitative assessment emphasises the reliability and applicability of the proposed model, making it a preferred choice for predicting tensile strength in Ferrock-infused concrete over conventional empirical models.

Sustainability assessment of FIC & CC

Figure 17 illustrates the impact of transporting raw materials for FIC & CC on GWP and energy use. The data shows that increasing the dosage level of FIC results in a steady rise in transport energy from 192.12 MJ-eq/kg to 208.68 MJ-eq/kg. However, the CC (T1) has a value of 187.98 MJ-eq/kg, which is lower than that of FIC. This indicates an approximate 11% increase from conventional concrete to FIC. The same pattern is observed in the GWP parameter, which increases from 13.14 kg CO₂-eq/kg to 14.58 kg CO₂-eq/kg, representing a 10% increase. A key point to note is that the raw materials used for FIC are significantly influenced by the distance to the sourcing location. Although it is locally sourced, transportation is achieved through low-emission logistics. During cement manufacturing, the embodied carbon release is nearly 0.85 kg CO₂-eq/kg, which may be attributed to the calcination process and fuel combustion. In contrast, the replacement of Ferrock leads to a reduction of almost 200 kgCO₂-eq/t. Meanwhile, the GWP from transportation is about 1.45 kg CO₂-eq/t, indicating a decrease of less than 1% in emissions. Therefore, even with a negligible increase in transport impact, the total embodied carbon of FIC remains considerably lower than that of the CC, as reductions from cement emissions would substantially lower its overall contribution.

Fig. 17.

Transport impact for FIC & CC.

Figure 18 presents the embodied energy for both cradle-to-gate and cradle-to-site conditions. It is clear that the varying and increasing percentage of Ferrock significantly reduces the embodied energy in both scenarios. For instance, the EE has dropped from 2547.72 MJ-eq/kg for CC to 1620.612 MJ-eq/kg for an FIC of 50%, showing a reduction of approximately 36%. The same pattern was noticed for the cradle-to-site boundary system. The reduction clearly demonstrates that lower energy demand is required for FIC production than for cement production.

Fig. 18.

Embodied energy for FIC & CC.

Figure 19 shows the GWP for FIC and CC, clearly indicating that the global warming potential steadily decreased as the amount of Ferrock increased. For conventional concrete, 396.68 kg CO₂-eq/kg and 208.63 kg CO₂-eq/kg Ferrock were used at a 50% level. A reduction of about 47% was observed when comparing conventional concrete to Ferrock-infused concrete at 50%. This significant decrease reveals that partially replacing cement with Ferrock, which is made entirely from industrial wastes as raw materials, reduces carbon emissions.

Fig. 19.

Global warming potential for FIC & CC.

The sustainability index for FIC & CC is shown in Fig. 20. The figure clearly demonstrates that a higher SI for FICs represents a more advantageous level in terms of both engineering properties and environmental impact. The sustainability index of 12.33 was observed for conventional concrete, whereas the values for ferrock were 10.82, 16.49, 17.83, 18.5, and 18.57 at levels of 10%, 20%, 35%, 40%, and 50%, respectively. Hence, it suggests that infusing ferrock with cement strengthens the environmental parameters.

Fig. 20.

Sustainability Index for FIC & CC.

Cost-effectiveness of concrete

Table 10 shows the prices (in USD, $) of various raw materials, including processing and transportation costs, for the study period. (financial year 2024–25). All costs and transport rates were obtained directly from local suppliers. The cost index of concrete mixes was examined in relation to their compressive strength^36,37, which is given in Eq. (6):

7

Table 10.

Prices of materials and other associated costs ($/kg).

Materials	Processing cost	Material cost	Transportation cost	Total price
Cement	–	0.1	0.0095	0.11
Ferrock	0.023	–	0.010	0.03
Oxalic Acid	–	0.8	0.010	0.81
Water	–	–	–	–
Fine Agg.	–	0.01	0.005	0.02
Coarse Agg.	–	0.01	0.005	0.02
SP	–	0.65	0.010	0.66

The cost-effectiveness of raw materials for CC (T1 mix) and FIC at 10% (T2 mix) is shown in Fig. 21a, with the total of all mixes displayed in Fig. 21b. From Fig. 19a, it is noted that the total cost per kg of concrete declined progressively, ranging from 83.64 $/kg to 75.74 $/kg. The cost reduction is mainly due to the gradual replacement of cement with Ferrock and oxalic acid. A similar trend was reported by Oyebisi et al. (xxx), in which replacing conventional binders with industrial by-products reduced the total material costs. Cement accounted for the largest share of the cost in T1, while its reduction in T2–T6 resulted in 8–10% total cost savings. Table 11 provides the cost index for all mixes. CI values increased from 1.97 $/kg·MPa to 4.86 $/kg·MPa because of the sharp decrease in compressive strength from 42.5 MPa to 15.6 MPa. Although T6 had the lowest production cost, its lower strength led to a higher economic index, showing reduced economic efficiency. Among all the mixes, T1 and T2 showed the best economic performance, with CI values below 2.0 $/kg·MPa. Notably, T2 (CI = 1.86) offered the best balance between lower cost and higher strength, indicating that adding a small percentage of Ferrock improves economic efficiency. Beyond T3, the loss in compressive strength outweighed the savings in material costs, causing a sharp increase in CI. This pattern was also noted by Oyebisi et al. (2022), where higher replacement levels led to lower strength development and thus reduced economic efficiency, despite lower material costs. Overall, the Ferrock-infused concrete emphasises the higher dosage level of Ferrock, improves sustainability, and lowers production costs. Thus, it supports the use of low-carbon, cost-effective materials and promotes a circular economy.

Fig. 21.

Cost- Analysis (a) Materials & other associated costs (b) Total Cost for FIC & CC.

Table 11.

Cost index of conventional & FIC.

	T1	T2	T3	T4	T5	T6
Compressive strength (MPa)	42.5	44.1	26.1	21.5	18.2	15.6
Total cost ($/kg)	83.64	82.06	80.48	78.9	77.32	75.74
Cost Index (CI)	1.97	1.86	3.08	3.67	4.25	4.86

Conclusions and future scope

The study evaluated the mechanical performance, durability, thermal resistance, microstructural characteristics, modelling prediction and environmental sustainability of Ferrock-infused concrete. Based on the experimental and analytical findings, the following conclusions are drawn :

• Ferrock can effectively substitute part of the cement in concrete, with 10% replacement offering the highest strength, enhanced durability, and improved thermal resistance.

• RCPT results showed a significant reduction in chloride ion permeation for the mixes consisting of 10–20% Ferrock, indicating better resistance to deterioration.

• Ferrock-infused concrete at 10% retained 94% of its strength at 200 °C, around 78% at 400 °C, and over 50% at 600 °C compared to conventional concrete under elevated temperatures.

• The addition of Ferrock produced a denser matrix with fewer visible pores and stronger particle bonding, which correlates with enhanced mechanical and durability behaviour.

• Response Surface Methodology confirmed that 10% Ferrock is the statistically significant optimal dosage, in line with experimental observations.

• The proposed Ferrock-infused concrete strength model demonstrated high accuracy, with an RMSE of 0.10 and a 95% normal efficiency factor, which outperforms both the international standards and previous research studies.

• Incorporating ferrock into cement concrete mixes improves overall efficiency by lowering transportation impact, embodied energy, and global warming potential. Better sustainability and cost metrics emphasize Ferrock’s potential as a low-carbon, cost-effective material that supports circular economy principles.

• Overall, the results confirm that Ferrock is a promising supplementary material capable of enhancing concrete performance while significantly aiding environmental sustainability.

Future scope

The present investigation emphasises the optimal level of 10% Ferrock in the cement concrete. However, further research would additionally address the long-term durability performance under other harsh environments, such as marine exposure, freeze-thaw cycles, and sulphate attacks. Further studies could investigate other industrial and/or agricultural waste materials and examine the techno-environmental aspects. A comprehensive ISO-LCA, incorporating broader life-cycle stages and impact categories as per PCR 2019:14, shall be rigorously assessed. Using machine learning or artificial intelligence models to predict performance outcomes based on material proportions could optimise mix designs for site-specific needs.

Author contributions

Conceptualization, Experimental investigation, Methodology, Formal analysis, Writing-original draft - D.S.V., P.D ; Validation, Visualization, Data curation, Writing- review and editing - K.R.S., R.J; Project administration: D.S.V., KRS.

Funding

This research is carried out under the SERB TARE project (Application number: TAR/2022/000537) with the help of Aarupadai Veedu Institute of Technology, Vinayaka Mission’s Research Foundation - DU (VMRF) and National Institute of Technology Calicut, NIT Campus.

Data availability

The authors declare that the data supporting the findings of this study are available in the form of figures and tables within the article.

Declarations

Competing interests

The authors declare no competing interests.