Effectiveness of Coconut Shell Ash for Corrosion Control in Concrete – An Experimental Approach

The significant contribution of the carbon dioxide emission from the production of Portland cement which is the main binder used in concrete has called for an imminent need to find environmentally friendly materials as alternatives. The availability of large quantities of agricultural wastes such as coconut shell in most developing countries opens a pathway to explore how these materials can be recycled into concrete as the binder composition. The combustion of most solid agricultural wastes results in the production of ash which can be used to replace Portland cement as a binder in concrete. This paper presents the results from the experimental investigation of the effect of coconut shell ash on the workability, mechanical properties, and embodied carbon of concrete. A total of five mixtures were made with coconut shell ash replacing Portland cement up to 20%. Results from this paper showed that coconut shell ash can be incorporated into concrete mixtures to reduce its embodied carbon. A reduction in embodied carbon of about 15% was achieved when 20% of Portland cement was replaced with coconut shell ash. The incorporation of coconut shell ash into concrete mixtures also resulted in an increase in the mechanical properties up to 10% replacement of Portland cement. The compressive, tensile, and flexural strength of mixtures incorporating 10% coconut shell ash as replacement of Portland cement is 12%, 10%, and 9% higher than that of the control mixture without coconut shell ash.

This study investigates the potential of coconut shell ash (CSA), an agricultural waste product, as a supplementary cementitious material (SCM) for sustainable concrete production. CSA, obtained from calcined coconut shells and rich in reactive silica, alumina, and iron oxides, was used to replace ordinary Portland cement (OPC) at 0%, 10%, 20%, and 30% by weight. A total of 224 concrete cubes were prepared using a 1:2:4 mix ratio and a constant water-to-cement ratio of 0.5, and were tested over 14 curing periods ranging from 3 to 91 days. Workability was measured using slump tests, while the elastic modulus was estimated based on compressive strength using the ACI 318-14 formula. Findings revealed that increasing CSA content led to reduced slump, indicating lower workability due to the ash’s porous and high-surface-area characteristics. However, the mix containing 10% CSA demonstrated an enhanced elastic modulus, peaking at 19.34 GPa on day 28, surpassing the control. This improvement is attributed to CSA’s pozzolanic activity, which promotes additional calcium silicate hydrate (C-S-H) formation, thereby densifying the concrete matrix. Higher replacement levels (20–30%) resulted in performance decline due to cement dilution. The study concludes that 10% CSA substitution offers an optimal balance between mechanical performance and sustainability in concrete.

Owing to the superior qualities, aluminum metal matrix composites (AMMC) have recently been accepted and suggested as a replacement for traditional materials in a variety of sectors, including automotive, agriculture, aerospace, sports, marine, and many more. To satisfy the industrial requirement, it is necessary to develop economical material with higher mechanical properties like strength, hardness, impact resistance etc. To minimise the environmental impact and depletion of natural resources , it is necessary to Reduce, Recycle and Resuse the solid waste created across the world. This work aims to study the mechanical behavior of hybrid composite of Al6061 reinforced with coconut shell ash (CSA) and granite dust solid waste. Hybrid composite specimens were successfully manufactured using stir casting method. The proportion of granite dust was kept constant at 2 wt percent, whereas the percentage of CSA varied, ranging from 0% to 12% with a multiple of 3. Tests for tension, compression, hardness, and impact were performed to examine the mechanical behavior of the created hybrid composites. SEM & EDAX analysis were carried out to study the microstructure and elemental composition of the hybrid composites. Experimental testing shows that, when the percentage of CSA in the hybrid composite increased, its tensile strength, compressive strength, hardness, and impact strength increased maximum upto 23.65%, 10.12%, 60.89% and 17.38% respectively as compared to base alloy. The experimental findings demonstrated that when compared to matrix and other hybrid composites, the Al6061 alloy reinforced with 2% granite dust and 12% CSA hybrid composite had superior mechanical properties.

High cost of cement used as binder in the production of concrete has led to a search for alternative. Using a mix design ratio of 1:2:4 and water binder ratio of 0.63, concrete cubes were casted using varying ordinary Portland cement (OPC): palm kernel shell ash (PKSA) and ordinary Portland cement (OPC): coconut shell ash (CSA) ratios of 100:0, 90:10, 80:20, 70:30 , 60:40 and 50:50 respectively. This research reveal that partial replacement of cement with 20% PKSA and CSA in concrete gives an average optimum compressive strength of 15.4 N/mm2 and 17.26 N/mm2 respectively at 28 days. While, the optimum value of compressive strength obtained at 28 days is 20.58 N/mm2 at 10% replacement with CSA. The value obtained is suitable for both light weight and heavy weight concrete respectively. Thus, the research show that the use of PKSA and CSA as a partial replacement for cement in concrete, at lower volume of replacement, will enhance the reduction of cement usage in concretes, thereby reducing the production cost and the environmental pollution caused by the dumping of the agricultural waste.

Many construction projects have encountered issues where the soil does not meet the necessary specifications for use as a subgrade layer. The high compressibility and low shear strength of these soils can lead to significant distortion when exposed to traffic loads. To address these issues, this study evaluated the impact of using natural additives namely coconut shell ash (CSA) admixed with lime. The research looked at how different types of treated soil and the quantity of chemicals used impacted the effectiveness of these additives. Variation portions of 2 %, 4 %, 6 %, 8 % and 10 % CSA with a constant 6% lime were used in the investigation. The study also examined how different variations of CSA and lime impacted the soil’s mechanical properties. Unconfined compressive strength (UCS) test was incorporated with curing times of 7, 14 and 28 days. The study's results found that using a combination of CSA and lime effectively improved the soil’s strength and durability. It conclusion, treated soil admixed with 6 % CSA and 6 % lime significantly improved the UCS as the value achieved 230.82 kN/m2 at 7 days. It's proven that untreated soil is more susceptible to water compared to treated soil.

Hybrid Alkaline Cement (HAC) has the potential to reduce carbon dioxide (CO2) and improve concrete structure. The durability of a hybrid alkaline mortar made from a mixture of calcined clay brick waste (CBW) and coconut shell ash (CSA) was compared with that of ordinary Portland cement (OPC) and pozzolanic Portland cement (PPC), which are the two common types of Portland cement. In an open furnace, CSA was obtained by burning coconut shells collected from Kilifi County, Kenya. At the same time, CBW was sampled from brick production and construction sites in Kibwezi sub-county, Kenya, and ground using a laboratory ball mill. Various cement blends were prepared by mixing different mass ratios of OPC:CSA: CBW and activated with 0.5 M and 2 M Sodium sulfate solutions, maintaining a solution-to-cement ratio of 0.5. Control mortar prisms were cast using distilled water and cured in distilled water. Principle Component Analysis (PCA) was used for correlation analysis. Compressive strength development, water sorptivity, Porosity, oxygen permeability index, and thermal resistance were investigated for durability properties. Accelerated chloride ingress and chloride ion diffusion coefficients were determined. Results show that alkali-activated samples exhibited lower sorptivity, Porosity, chloride ingress, and higher compressive strength, oxygen permeability index, and thermal resistance than the cement mix prepared with water. The mix designs 5-1-4, 5-4-1, 3-1-6, and 3-6-1 demonstrated a decreasing optimum performance comparable to OPC in that order. The formulation 5-1-4, prepared with 2 M Sodium sulfate, showed the highest durability in all tests. Moreover, mortar durability was highly influenced by the amount of cement substituted, the kind of precursor, and the concentration of alkali activator.

The cost of cement used in concrete works is on the increase and unaffordable, yet the need for hydraulic cement concrete and other cement concrete based infrastructures keeps growing with increasing population, thus the need to find alternative binding materials that can be used solely or in partial replacement of cement. The use of waste materials with pozzolanic properties in concrete production is a becoming a worldwide practice. The assessment of the pozzolanic activity of cement replacement materials is becoming increasingly important because of the need for more sustainable cementing products. In this study, a mixture of coconut shell ash and eggshell powder is used as partial replacement of hydraulic cement in ranges of 0%, 5%, 10%, 15%, and 20%. The concrete specimens were prepared at 1: 3: 2.5 mix ratio of cementitious material, fine aggregate and coarse aggregate. The mix ratio satisfied the minimum cement content of 148.32kg/m3 (250Ib/yd3) and the minimum cementitious material content of 267 kg/m3 (450Ib/yd3) for roller compacted concrete pavement. The compressive strength, splitting tensile strength and flexural strength tests were carried out to assess the strength characteristics of ternary concrete mixture containing coconut shell ash and eggshell powder and the feasibility of using coconut shell ash and eggshell powder as partial replacement of cement in industrial plant access concrete roads and parking lots. The results indicate that a mixture of coconut shell ash and eggshell powder can be used up to 20% by weight for replacement of cement in roller compacted industrial plant access concrete roads and parking lots.

<title>Abstract</title> Concrete is essential in construction, but its production is energy-intensive and polluting. This study investigates using coconut shell ash (CSA) as a supplementary cementitious material (SCM). This approach not only prevents waste but also recovers energy from the combustion of coconut shells. India was selected as a case study, being the third-largest coconut producer and the second-largest cement manufacturer.The research employs a Consequential Life Cycle Assessment (LCA) to systematically evaluate the environmental performance of these novel concrete mixes, alongside a comprehensive assessment of the pozzolanic activity of the ashes, and mechanical properties to confirm structural suitability. We conducted an extensive global sensitivity analysis (GSA) on the system parameters, since we are assessing a future scenario and the model is uncertain, particularly concerning the current treatment in India.Including CSA in the concrete mix significantly reduces flexural and compressive strength, primarily because the ash lacks effective pozzolanic properties and acts mainly as an inert filler that retains water, hindering optimal cement hydration. Results demonstrate significant reductions in environmental impacts across 13 of 16 assessed impact categories, primarily due to the substitution of heat and electricity from incineration. These results are confirmed by the GSA.While incinerating coconut shells in India significantly reduces the GWP, primarily due to energy recovery, the resulting ashes are not suitable as a SCM due to their poor mechanical performance, lack of pozzolanic reactivity, and high carbon content.

Geopolymer is an environmentally attractive Portland cement substitute, owing to its lower carbon footprint and its ability to consume various aluminosilicate waste materials as its precursors. This work describes the development of geopolymer formulation based on biomass-coal ash blends, which is predicted to be the prevalent type of waste when biomass-based thermal energy production becomes mainstream in Indonesia. The ash blends contain an ASTM Class F coal fly ash (FA), rice husk ash (RHA), and coconut shell ash (CSA). A mixture of Na2SiO3 and concentrated KOH is used as the activator solution. A preliminary experiment identified the appropriate activator/ash mass ratio to be 2.0, while the activator Na2SiO3/KOH ratio varies from 0.8 to 2.0 with increasing ash blend Si/Al ratio. Both non-blended FA and CSA are able to produce geopolymer mortars with 7-day compressive strength exceeding the Indonesian national SNI 15-2049-2004 standard minimum value of 2.0 MPa stipulated for Portland cement mortars. As...

The escalating environmental burden of ordinary Portland cement (OPC) Grade-53 production, accounting for 8-10% of global industrial CO2 emissions, has necessitated the exploration of sustainable alternatives through supplementary cementitious materials (SCMs). This comprehensive review synthesizes 52 peer-reviewed studies (2020-2025) to establish systematic material selection criteria for cement replacement using different types of ash, including coal bottom ash (CBA), fly ash (FA), rice husk ash (RHA), wood bottom ash (WBA), sugarcane bagasse ash (SCBA), coconut shell ash (CSA), and agricultural residue ashes. The research develops a multi-dimensional selection framework encompassing chemical composition analysis (SiO2, Al2O3, CaO content), physical properties (particle size, water absorption, bulk density), pozzolanic activity assessment, mechanical performance metrics (compressive, flexural, and tensile strength), durability characteristics, and environmental/sustainability parameters. Key findings reveal optimal replacement percentages: coal bottom ash (20-35%), fly ash (25-30%), rice husk ash (5-10%), wood bottom ash (5-15%), and sugarcane bagasse ash (10-15%), with coal bottom ash demonstrating 28.78% strength improvement at 35% replacement and 34% CO2 emission reduction. The framework incorporates application-specific selection algorithms, quality control protocols, durability testing methodologies, and practical implementation guidelines. Challenges identified include inconsistent properties in agricultural ashes, early strength loss, water demand increases, alkali-silica reaction (ASR) risks, and batch-to-batch variability, with corresponding mitigation strategies detailed. This study establishes a decision-support system enabling engineers and researchers to systematically select appropriate ash materials based on specific project requirements, environmental goals, and performance standards. Future research directions emphasize standardization of agricultural waste ashes, development of hybrid ash systems, integration of machine learning for property prediction, and long-term durability validation (&gt;10 years), supporting the transition toward circular economy principles in sustainable construction.

WITHDRAWN: Analysis the effect of coconut shell ash powder on cement block

Process parameters optimization for eco-friendly high strength sandcrete block using Taguchi method

Materials selection and development for application in advanced systems is becoming highly complex involving the need for lower cost alternatives without compromising service performance. This paper investigated selected critical mechanical properties of ceramic matrix composites synthesized from coconut shell carbon (CSC) reinforced with silica particles (SP). Coconut shells (CCS) and silica sand (SS) were pulverized separately in a plate mill and a ball mill respectively to obtain a particle size of 250 μm. The CCS powders were calcined at 5000 C in an oven to obtain coconut shell ash (CSA) which was carbonized in a furnace from 5000 C-10000 C under argon gas controlled environment. The materials were mechanically blended while the SP additions varied from 10-40 wt. % and compacted using hydraulic press. The compacted mixture was sintered at 5000 C-12000 C, held for 2 hrs and the composites characterised for mechanical properties while the microstructural integrity was analysed using scanning electron microscope/energy dispersive x-ray spectroscopy (SEM/EDS). Microstructure showed that after sintering, coconut shell carbon developed strong cohesion with the silica particles which gave rise to effective load transfer. The mechanical properties that ensued demonstrated on the average 52.8 % comparability with conventional power plant structural materials in terms of hardness, compressive strength and impact energy.

The aim of this study is to investigate the effect of adding fly ash, an industrial by-product and coconut shell, an agricultural waste on the mechanical and flexural characteristics of eco-concrete. The study focuses on density, compressive strength, tensile strength and flexural behaviour of the coconut shell eco-concrete. Two different mixes are developed, one with coconut shell and the other with conventional aggregate and coconut shell as coarse aggregate. The cement content is replaced with class F fly ash at 0%, 10%, 20% and 30% by weight. The test result shows that the coconut shell concrete produced with 10% fly ash has recorded higher compressive, tensile strength than other proportions. Fly ash inclusion further reduces the density of coconut shell concrete. The higher deflection of coconut shell concrete before failure shows that it has failed in a ductile manner. The flexural behaviour is comparable with other lightweight concretes. It is suggested that an eco-friendly, cost effective structural lightweight concrete can be produced by using coconut shell and fly ash.

One of the most common types of waste produced by the agriculture sector all over the world is coconut shells. However, cement manufacturing in the construction industry is responsible for billions of tons of carbon dioxide emissions annually. This study investigated the feasibility of using coconut shell ash (CSA) as a cement substitute in concrete manufacturing to mitigate the aforementioned agro waste disposal issue and the environmental consequences of the expanding construction sector. In addition, treated and untreated coconut fibers were used as reinforcements in concrete. The CSA proportions in the blend designs used in the investigation varied from 0-20 % at 5 % increments, while the coconut fiber reinforcements varied from 0-1 % at 0,25 % increments. Tests were performed on both fresh and hardened concrete, including slump tests and mechanical property evaluations after 28 days of curing. The results indicated that adding more than 10% coconut shell ash decreased the workability and compressive strength of the concrete when compared to conventional mixes. At 28 days of curing, the compressive strengths of concrete mixes with 5, 10, 15 and 20 % replacement levels were 29,50; 26,50; 24,80; and 22,67 MPa, respectively.