Fly Ash Replacement Research Articles

Experimental Research on the Performance of Recycled Waste Concrete Powder (RWCP) on Concrete.

Waste concrete is a large amount of solid waste produced in the process of urban construction and renewal in China. Its resource utilization is of great significance for saving mineral resources and improving urban environmental quality. The present study was designed to investigate the effects of mechanical grinding time on the particle size distribution and activity of recycled waste concrete powder (RWCP). Combined with unconfined compressive strength, slump, electric flux and chloride ion penetration resistance tests, the effects of RWCP on the mechanical properties, working performance and impermeability of concrete were analyzed, and the phase and microstructure of concrete containing RWCP were analyzed by XRD and SEM. The results showed that the RWCP is mainly composed of quartz, gismondine, C2S, cancrinite and portlandite. The optimum activity of RWCP obtained by ball milling for 45 min was 44.41%. RWCP can improve the fluidity of concrete and shorten the initial setting time of concrete. When the blast furnace slag in the concrete was replaced by the RWCP, the early strength and impermeability of the concrete decreased. When RWCP replaced blast furnace slag by 69.1%, the UCS of the concrete at 1, 3, 7, and 14 d decreased from 9.56, 22.1, 34.1, and 41.2 MPa to 5.9, 14.5, 22.7, and 33.2 MPa, respectively. While RWCP replaced fly ash, the normal strength of concrete increased with the increase in fly ash replacement amount. When RWCP completely replaced FA in concrete, the 28-day strength of the concrete increased from 45.2 MPa to 50.8 MPa. The impermeability results showed that the appropriate substitution of RWCP for fly ash was beneficial to increase the impermeability of concrete while excessive substitution reduced. Based on these results, the RWCP has the potential for large-scale application in the preparation of concrete.

Cyclic loading effects on the heat-generation performance of carbon nanotube-embedded cement composites

Abstract This study investigates the heat-generation stability of carbon nanotube (CNT)/cement composites after exposing to cyclic loading conditions. The specimens were fabricated with varying CNT contents and levels of fly ash replacement. Results showed that increasing CNT content reduced electrical resistivity, while the impact on the electrical characteristics was found to be insubstantial, even though a considerable portion of fly ash was replaced. In addition, the electrical resistivity of the specimens after exposed to cyclic loading increased. Electrical heating tests revealed both negative and positive temperature coefficient effects depending on the applied voltages. Higher CNT contents improved the heat-generation capability, but the heating capability decreased after exposed to the cyclic loadings which is deduced from the damage of CNT networks during cyclic loadings. In this regard, the authors concluded that the heat-generation stability can be significantly affected by the applied loadings. Thus, the future research will be conducted to improve the heat-generation stability of the cement-based electrical heating systems as exposed to artificial deteriorations.

Comparative Study of Mechanical Properties of Self Compacting Concrete Using Binary Pozzolanic Materials

Abstract: The study examined the viability of using waste supplementary cementing materials (SCMs), such as fly ash (FA) and silica fume (SF), as partial replacement of Ordinary Portland cement. The way SCC's fresh properties and hardened were impacted by FA and SF. The study examined the fresh characteristics and hardened characteristics of various distinct SCC mixes using SCC with partial replacement of Ordinary Portland Cement with FA (class F) and SF. First, the cement was replaced by percentages in the mixes 0%, 10%, 15%, 20%, 25%, and 30% by FA and constant replacement of 10% by SF. Then cement was replaced by percentages in the mix with 25% FA constant and 4%, 6%, 8%, 10%, and 12% by SF. For every combination, the water/binder (w/b) ratio was set at 0.43. The EFNARC (Specification and Guidelines for Self-Compacting Concrete) standards were met by the slump flow, T50, and viscosity of the SCC. After 28 days of curing, the blend consisting of 65% PC, 25% FA, and 10% SF had a maximum compressive strength of 41.22 MPa which is 12.07% greater than the compressive strength of the control specimen which is 36.78 MPa. The Split Tensile Strength of the same blend is 4.37% is greater than the control specimen. Non-destructive tests were also performed after 28 days of curing and the regression equations give the excellent relationship between Rebound Number, Ultrasonic Pulse Velocity, and Compressive Strength. This is due to the formation of the proper matrix as the particle size of SF and FA is less than that of cement and the free lime of cement reacts with FA and SF to form C-S-H gel which provides strength.

Shrinkage reduction mechanism of low Ca/Si ratio C-A-S-H in cement pastes containing fly ash

Understanding the drying shrinkage of low Ca/Si ratio cement pastes is crucial for promoting the use of low-clinker ratio cementitious materials and reducing the environmental impact of cement production. We prepared well-hydrated cement paste samples with various fly ash replacement and water-to-cement ratios. The long-term drying shrinkage was measured by 1 mm-thick samples. Results showed that fly ash containing samples exhibited lower shrinkage and the irreversible part of drying shrinkage was less compared to those without fly ash. Chemical composition analysis of the calcium aluminate-silicates hydrate (C-A-S-H) was conducted using X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDS). Additionally, water vapor sorption isotherms and proton nuclear magnetic resonance (1H NMR) relaxometry were used to determine specific surface area and pore structure. By analyzing these results in conjunction with the C-A-S-H model, we attributed the reduced and more reversible drying shrinkage in fly ash cement to lower Ca ion amounts in the interlayer space and fewer trapped larger pores.

Improvement of properties of high volume fly ash based self-compacting mortar with dolomite and ground granulated blast furnace slag

Usage of filler with inert or pozzolanic property has been crucially required for fabricating the practicalself-compacting mortar or self-compacting concrete. The current study investigates the influence of usingthe dolomite powder on the enhanced properties of the high volume Class F fly ash self-compacting mortarwith/without addition of ground granulated blast furnace slag (GGBFS/slag). Experimental results showed thatpartial replacement of low calcium Class F fly ash with the dolomite powder not only increased the workability of the fresh modified self-compacting mortars but also enhanced the ordinary Portland cement hydrationprocess at early. The adjustment of dolomite powder addition as partial replacement of fly ash resulted in themodified self-compacting mortars with the compressive strength increased after 7 days of curing. 30 masspercent of dolomite powder partially replacing fly ash was considered as the optimum value to induce the hardened modified self-compacting mortars with the compressive strengths increased at 4.2, 10.4, and 10.5% at3, 7, and 28 days, respectively. With the content of dolomite powder being fixed at 30 and 50 mass percent,partial replacement of fly ash with slag at 50 mass percent induced the modified self-compacting mortars withsignificant enhancement of the engineering properties.

Numerical and experimental analysis of the effect of multi-ion electrical coupling on the sulfate convection zone in hydraulic concrete

This study centers on investigating the effects of multi-ion electrical coupling on sulfate profiles in the convection zone of hydraulic concrete under drying-wetting cycles. Considering the moisture ingress triggered by capillary negative pressure and electrical potential gradients generated due to the varying speeds of the charged solutes, a coupled numerical model framework for moisture and multi-component ions transport is established. The influence of drying and rewetting conditioning regimes, electrochemical coupling between multi-species ions, sulfate adsorption-binding mechanism, fly ash replacement and porosity of concrete on moisture and multi-ion transport behavior is numerically analyzed. Our findings reveal that more than 60 % of the sulfate ions that penetrate the concrete matrix engage in chemical reactions. After 30 cycles, the sulfate ion content differs by approximately 21 % depending on the presence of the electrical coupling effect. Moreover, the electrostatic potential in the pore solution fluctuates sharply in the ion-rich area near the concrete surface, interacting with ion distribution in the convection zone. The knowledge gleaned from this investigation offers a robust framework for the design of concrete structures that need to withstand challenging aqueous environmental conditions marked by multi-component ions and cyclic drying-wetting processes.

Apparent Influence of Anhydrite in High-Calcium Fly Ash on Compressive Strength of Concrete

This case study investigates five fly ashes with high CaO and SO3 levels in their chemical composition and compares the apparent influence of the presence and absence of anhydrite on compressive strength. Another distinguishing feature of the above ashes is that they, more or less, naturally contain anhydrite. Two different series of mixed proportions were adopted. Series 1 is designed to understand the maximum possible replacement level of fly ash. Series 2 is designed to understand the effect of anhydrite on compressive strength development. The mineral composition and glass phase of fly ashes were determined by X-ray diffraction Rietveld analysis. As a result of this study, we have found that concrete containing anhydrite-rich fly ash exhibits a higher strength than concrete containing anhydrite-free fly ash at all ages. The compressive strength increases with an increasing fly ash replacement ratio when anhydrite-rich ash is used, but strength decreases when the replacement level exceeds a certain point. The optimal amount of anhydrite was 2 ± 0.5 kg/m3 of concrete, excluding the anhydrite contained in cement.

Investigation on Cement-Stabilized Base with Recycled Aggregate and Desert Sand.

This paper mainly explores the feasibility of using desert sand (DS) and recycled aggregate in cement-stabilized bases. Recycled coarse aggregate (RCA) and DS serve as the substitutes of natural coarse and fine aggregates, respectively, in cement-stabilized bases. A four-factor and four-level orthogonal test is designed to analyze the unconfined compressive strength, splitting tensile strength, and compressive resilient modulus. Furthermore, this paper investigates the effects of cement content, fly ash (FA) replacement rate, RCA replacement rate, and DS replacement rate on the road performance of cement-stabilized bases composed of RCA and DS. The test results reveal that the performance of cement-stabilized bases with partial RCA instead of natural coarse aggregate (NCA) and partial DS instead of natural fine aggregate satisfies the road use. The correlation and microscopic analyses of the test results imply the feasibility of applying DS and recycled aggregate to cement-stabilized bases. This paper calculates and evaluates the life cycle of carbon emissions of desert sand and recycled coarse aggregate cement-stabilized macadam (DRCSM) and finds that both DS and RCA can reduce the carbon emissions of CSM, which has a positive effect on improving the environment and solving the climate crisis. It is hoped that this paper can offer a solid theoretical foundation for promoting the application of DS and recycled aggregate in road engineering.

Behavior of controlled low-strength material incorporating industrial by-products fly ash, quarry waste and concrete waste

The widespread generation of concrete waste from demolished structures presents a significant challenge in construction waste management. However, its integration into Controlled Low Strength Material (CLSM) presents a promising avenue for sustainable construction for utility fill or backfilling applications when suitable granular fills are not available. A low strength flowable fill mix necessitates a mix design that achieves a compressive strength below 0.7 MPa after 28 days for easy excavatability using hand tools. This study delves into the feasibility of replacing fly ash by incorporating concrete waste and quarry waste into CLSM formulations with minimal amounts of cement through laboratory investigations to engineer CLSM blends optimized for easy excavation, particularly for utility fills. Results indicate that the inclusion of concrete waste reduces the water demand and mitigates bleeding in CLSM, thereby enhancing the overall stability of the mix. Moreover, CLSM compositions exhibit densities akin to the density of sand. The addition of 10 % and 20 % of concrete waste led to substantial increases in unconfined compressive strength (UCS). The impact was more pronounced at lower cement contents, with significant early strength development observed when concrete waste was included.The split tensile strength was found to have a linear correlation with the UCS and the dry density of the mix. The formation of pozzolanic hydration products, particularly in mixes with higher fly ash content, was identified as a key factor contributing to strength development, while increased friction between particles of quarry waste further increased the strength and the same has been confirmed using scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The findings also revealed that a CLSM blend composed of, 30 % fly ash, 50 % quarry waste and 20 % concrete waste supplemented with an extra 3 % cement at 250 mm flowability could be used for backfilling applications where sufficient strength and excavatablity with hand tools is required.

STUDY ON PERFORMANCE OF CONCRETE BY PARTIAL REPLACEMENT OF CEMENT WITH FLY ASH AND INCLUDATION OF NANO MATERIAL

STUDY ON PERFORMANCE OF CONCRETE BY PARTIAL REPLACEMENT OF CEMENT WITH FLY ASH AND INCLUDATION OF NANO MATERIAL

Development of eco-friendly engineered cementitious composites (ECC) with both waste glass powder and aggregate: A comprehensive investigation

This study investigated the micro-macro properties of engineered cementitious composites (ECC) with both waste glass powder (WGP) and waste glass aggregate (WGA) as substitutes for binder and silica sand, aiming to achieve sustainable ECC materials and recycle waste glass in a high-value approach. The results indicate that a high volume of WGP used as a replacement for cement leads to a loose microstructure in ECC, whereas ECC prepared with 100 % WGA replacing silica sand exhibit a better microstructure compared to the reference ECC. Replacing cement with a high volume of WGP reduces the compressive and flexural strengths, but replacing silica sand with WGA increases the compressive and flexural strengths of ECC. Under tensile loading, both WGP replacing binders and WGA replacing silica sand enhance the strain capacity of ECC at substitution rates not exceeding 25 %. As the substitution rate increases, replacing 50 % of cement with WGP reduces the strain capacity and ultimate tensile strength of ECC by 18 % and 32.5 %, respectively. Nevertheless, substituting WGA for silica sand can enhance the strain capacity of ECC. Substituting WGP for the binders increases the transport properties and water-permeable porosity of blended ECC, while the replacement of silica sand with a moderate dosage of WGA reduces the water transport properties and water-permeable porosity. The simultaneous substitution of binder and silica sand with WGP and WGA, respectively, enables the production of sustainable ECC with desirable micro-macro properties. The complete replacement of silica sand and fly ash with WGA and WGP, respectively, is feasible, whereas the substitution of cement with a high-volume WGP should be limited.

Transport Properties of Internally Cured Self Compacting Concrete with Fly Ash

Proper curing of concrete has a major beneficial effect on the transport properties of concrete which in turn influences its durability. This paper attempts to study the effect of fly ash on the transport properties of internally cured Self-Compacting Concrete specimens under ambient conditions. Two internal curing materials, Lightweight Expanded Clay Aggregates [LECA] and Superabsorbent Polymer [SAP] were chosen for the study. Properties such as sorptivity, resistance to chloride ion penetration and chloride ion migration specimens with varying percentages of fly ash replacement from 30% to 50% are presented under different curing conditions namely conventional curing, sealed curing with internal curing materials and ambient curing with internal curing materials. The results showed that the impermeability of concrete improved with an increasing percentage of fly ash replacements owing to the presence of internal curing water to improve hydration along with fly ash that moderates the heat of hydration and drying. The internal curing efficiency also improved with the increase in the percentage of fly ash replacement. Under ambient conditions, the mixes with fly ash above 45% replacement have shown very good mechanical and durability properties indicating a refined pore structure leading to enhanced transport properties.

Unleash the potential of mechanically activated Iron ore tailings in cement mortar containing silica fume and fly ash

This paper presents the effects of mechanically activated Iron Ore Tailings (IOT) in cement mortar containing silica fume, fly ash, and Ordinary Portland Cement (OPC). Five different mixes (i.e. M1- M5) were prepared which include control mix (M1), replacement of cement with IOT (M2), replacement of cement with IOT and silica fume (M3), replacement of cement with IOT and fly ash (M4), and replacement of cement with IOT, fly ash and silica fume (M5). Results reveal that utilization of mechanically activated IOT with 30% replacement of cement, 20% replacement of fly ash, and 10% replacement of silica fume performs well in flowability and compressive strength of cement mortar.

Physical, mechanical, and microstructural characteristics of fly ash replaced cement deep mixing columns

The novel approach of the study is implementing the installation procedure of fly ash (FA) replaced cement deep mixing (DM) columns to field cases aiming at managing FA waste and reducing cement utilization. FA replaced cement DM columns (diameter of 30 cm and length of 80 cm) were installed on clayey soils using a laboratory type DM machine. The effect of installation parameters such as the binder dosage, FA replacement ratio, superplasticizer content, water/binder ratio, and the liquidity index (LI) of the soil on column performance was investigated. The design of experiments and optimization process were conducted using the Taguchi method, S/N and ANOVA analyses, and the desirability function method. Observations have shown that the mixing time required for a homogeneously mixed column depends on the LI of the soil and the volume ratio (VR) of the slurry. A key parameter (LI∙VR) is defined to decide the minimum number of the mixing process. The blade rotation number should be minimum of 252 rev/m to obtain a homogeneous soil-slurry mixture. The highest strength of the column was obtained when LI of fresh soilcrete (LImix) is 1.25∙LI. Optimum installation parameters were determined as binder dosage of 425 kg/m3, FA replacement ratio is 40%, superplasticizer content is 3%, water/binder ratio is 0.8, and LI of the untreated soil is 1. In the optimum design, the mixing efficiency of the soil-slurry mixture increased and the best column performance was obtained. In addition, cement utilization and binder cost decrease 40% and 33%, respectively, in FA-replaced cement DM columns. SEM images prove the increase in column performance due to the cementation products (CSH and CAH gels) formed in the microstructure of the column.

Prediction of the heat of hydration of fly ash concrete by adiabatic temperature rise test and regression analysis

This paper deals with the proposal of a model that can predict heat of hydration of concrete containing fly ash and the adiabatic temperature rise test results that are the basis of the model. For the adiabatic temperature rise tests, total of twelve concrete mixtures were prepared with variables of the percentage of fly ash replacement and w/cm. The test results indicate that the replacement of fly ash significantly reduces the adiabatic temperature rise and delays the early hydration of fly-ash blended cements. Additionally, w/cm was found to influence not only the maximum adiabatic temperature rise but also the slope of the temperature rise. Therefore, a regression analysis was conducted to propose three parameters (hydration time parameter, hydration slope parameter, ultimate degree of hydration) for the heat of hydration model of concrete containing fly ash. The developed heat of hydration model was validated using test data. Models that did not consider w/cm, similar to those proposed by other researchers, failed to accurately predict the test results. However, the final model developed, which incorporates w/cm, accurately predicted the test results, as confirmed through this study.

Assessing viability and leachability in fly ash geopolymers incorporated with rubber sludge

This study explores the innovative use of rubber sludge (RS) from glove manufacturing as a partial replacement for fly ash (FA) in geopolymer production. The research investigates the physical properties, functional group analysis, microstructural analysis, phase analysis and compressive strength. The partial replacement of different types of RS, such as activated sludge (AS), pre-leaching sludge (PLS) and coagulant sludge (CS), will affect differently on the geopolymer integrity and performance. CS enriched with high calcium content, facilitated the formation of a denser geopolymer matrix with C(N)-A-S-H gel in conjunction with C-S-H, C-A-S-H and N-A-S-H gels, enhancing the compressive strength of FA/CS geopolymers up to 70.4 MPa, surpassing FA/AS and FA/PLS geopolymers. The fly ash/rubber sludge geopolymers exhibited compressive strengths ranging from 20.5 to 70.4 MPa, not only meeting ASTM standards for construction but also effectively immobilizing hazardous metals, particularly Zn (>98.4 %), the Zn leaching in geopolymers was reduced by more than 87.4 % compared to the rubber sludge itself, thereby mitigating environmental toxicity. This utilization addresses significant industrial waste management issues, providing a cost-effective and environmentally friendly alternative for construction. The findings contribute to advancing sustainable building materials and advocate for equitable utilization of industrial waste resources.

Developing geopolymer concrete using fine recycled concrete powder and recycled aggregates

To develop a sustainable geopolymer concrete (GC), the efficacy of using fine recycled concrete powder (FRCP) and recycled aggregates (RA) as partial replacements for fly ash (FA) and natural aggregates (NA), respectively, was investigated. The compressive strengths of different GCs were measured. The durability performance was assessed by means of capillary suction tests, initial surface absorption tests and acid attack performed at ambient curing. The compressive strength of the GC made with 50% RA (both coarse and fine) and FRCP was found to be comparable to that of GC made with NA. Similarly, the inclusion of FRCP in the GC mixes resulted in a pore-blocking effect, restricting water ingress to the GC through capillary suction and surface absorption, even with the use of 50% coarse RA and 25% fine RA. The results demonstrated that sustainable GC can be developed using appropriate doses of FRCP and RA.

Long-term and accelerated swelling of steel slag-glass powder and steel slag-fly ash mixtures as sustainable geo-materials

The volumetric instability of steel slag hinders its use in pavement layers and embankments. Accordingly, evaluating the swelling potential of steel slag and designing volumetrically stable steel slag mixtures is required to promote its sustainable utilization. This paper focuses on the comparison of the swelling response of basic-oxygen-furnace steel slag (BOFS), electric-arc-furnace steel slag (EAFS), BOFS-fly ash and BOFS-glass powder mixtures based on the results of three different types of tests: (i) long-term California bearing ratio (CBR) swelling, (ii) heated water bath swelling and (iii) autoclave tests. BOFS mixtures were prepared using glass powder or class F fly ash with 5%, 10%, and 20% replacement ratios. The compaction characteristics, permeability, and California bearing ratio (CBR) of steel slag and steel slag mixtures were also assessed within the framework of a detailed discussion of their swelling response. At the end of swelling tests, the measured maximum 1D strains of EAFS were all at negligible levels. Based on the test results, BOFS and BOFS-glass powder mixtures had ∼5.0–5.5% swelling strains after 20.5 months without signs of stabilization. 20% class F fly ash replacement stabilized the swelling strains of the mixture at about 0.75% after ∼3 months of monitoring in long-term tests. 1D swelling rates measured for all BOFS-class F fly ash mixtures decreased with increasing fly ash content. CBR and swelling response of BOFS-class F fly ash mixtures were more favorable compared to those of BOFS. The heated water bath tests provided higher estimates of the swelling strains compared to those obtained from autoclave tests for the steel slag mixtures that contain 15% or more fines. The results of this study showed that glass powder replacement is not effective in alleviating the swelling of BOFS. The volumetrically stable BOFS-class F fly ash mixtures indicated favorable mechanical properties for their use in pavement layers.

A comprehensive study on engineering and sustainability characteristics with emphasizing on 3R's approach in building construction

The study assesses the mechanical efficiency, long-lasting characteristics, microstructure, and sustainability of sustainable concrete (SC) samples through several optimization methods, emphasizing the significance of the 3Rs (recycle, reuse, reduce) approach in the construction sector. The study uses advanced techniques like the Taguchi method, grey relational analysis (GRA), analysis of variance (ANOVA), and signal-noise ratio (SNR) to optimize parameters affecting the performance of SC. In this study, the properties of SC are assessed by considering various parameters. These parameters include the use of 10 %, 20 %, and 30 % of ground granulated blast furnace slag (GGBFS) as a replacement for fly ash (FA). Additionally, six different binder contents ranging from 300 kg/m3 to 600 kg/m3 are examined. The study also investigates three different molarities of sodium hydroxide (NaOH) (8 M, 12 M, and 16 M), three different ratios of alkaline activators (AA) (1.5, 2.0, and 2.5), three different AA to-binder ratios (0.30, 0.35, and 0.40), and curing temperature (CT) of 30 °C, 60 °C, and 90 °C. The study includes fresh properties such as fresh density (FD) and slump, mechanical properties such as tensile strength (TS), flexural strength (FS), modulus of elasticity (MOE), and compressive strength (CS), and durability studies such as dry density (DD), impact strength, water absorption (WA), and sorptivity. The blended proportions were obtained using the Taguchi method. The study shows that GGBFS accelerates geopolymerization in FA-based concrete, reducing setting time and early-age CS. FA is crucial for setting time, workability, and CS enhancement. GGBFS increases the densities of fresh and hardened concrete, with a highly correlated increase, allowing accurate hardened density prediction with a coefficient of 0.9057. The CS of the cube SC surpassed 40 MPa, irrespective of variables such as the AA ratio, CT, and NaOH molarity. The trail mix with a binder concentration of 600 kg/m3, 30 % GGBFS content, 12 M NaOH molarity, 1.5 AA ratio, 0.35 AA to binder ratio, and 90 °C CT exhibited the greatest strength. Mixtures containing 10 % GGBFS can attain a CS above 30 MPa after 28 days, making them suitable for structural purposes. The T18 mix exhibited a compact Calcium (alumino) silicate hydrate (C-A-S-H) and N-A-S-H gel, whereas the T3 mix displayed a varied and permeable structure. The study used GRA, ANOVA, and SNR methods to analyze properties varying by six variables, finding GGBFS content as the most influencing parameter. The study found that the SC had a lower sustainability score than the OPC mix, but had better energy efficiency.

Effects of coal fly ash as partial replacement for cement towards concrete properties

Abstract The use of industrial waste, particularly fly ash (FA), as a substitute for ordinary portland cement (OPC) has gained attention due to global trends promoting the recovery and utilization of waste materials in construction. Previous research has demonstrated that fly ash has the potential to replace cement without compromising the strength of concrete, driving further exploration and validation of this concept. In a study investigating the effects of fly ash replacement in concrete, different percentages of fly ash were used to replace OPC in C25 grade concrete. Various tests were conducted, including X-ray fluorescent (XRF) analysis, sieve analysis, workability test, compression test, and water absorption test, to assess the characteristics, properties of the materials, fresh and hardened concrete. The results indicated that the replacement of FA in cement showed significant effects, with the strength at 12.5 % and 15 % replacements reaching the target strength of pure concrete at both 7 days and 28 days. These findings suggest that fly ash, at these replacement levels, exhibits desirable strength comparable to OPC, making it a viable alternative.