Utilization of Agricultural wastes as biochar’s and pozzolanic ashes in cementitious blends

doi:10.21203/rs.3.rs-4979519/v1

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Utilization of Agricultural wastes as biochar’s and pozzolanic ashes in cementitious blends

https://doi.org/10.21203/rs.3.rs-4979519/v1

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Agricultural activities tend to produce a lot of waste in their operation. These wastes, if not properly disposed of, cause environmental pollution. This agricultural waste (biomass) can be utilized into valuable materials like rice husk ash (RHA) and biochar. Ordinary Portland Cement (OPC) is the primary binder in standard cementitious mixes and a significant contributor to CO₂ emissions. This study investigates the utilization of RHA and biochar as supplementary cementitious materials to minimize the need for OPC. This research adopts pyrolysis and controlled combustion to convert rich husk (agricultural waste) to produce RHA and biochar. In order to establish RHA and Biochar's suitability as SCM, chemical composition techniques (X-Ray Diffraction analysis, X-Ray Fluorescence analysis, and Ultrasonic Pulse Velocity test) and mechanical performance testing (compressive strength tests of various mortar mixes with varied percentages (0%, 5%, 10%, and 15%) replacement of RHA and Biochar by weight of cement) were conducted. The findings showcased that partially replacing OPC with RHA and biochar in cementitious mixes improves mechanical performance and durability while maintaining a lower carbon footprint. Utilization of agricultural waste in cementitious materials encourages efficient circular economy principles as well as environmentally sustainable infrastructure. This study highlights how using bio renewable resources can lead to sustainable development.

Rice Hush Ash (RHA)

Biochar

supplementary cementitious materials (SCMs)

Ordinary Portland Cement (OPC)

Pyrolysis

Cementitious materials serve numerous uses in the construction industry due to their cost-effectiveness, high performance, adaptability, and ease of access. The number of people living in cities has significantly increased as a result of increased industrialization, urbanization, and economic growth. Cementitious materials are utilized in urban areas to improve housing standards by enhancing their durability and serviceability. Ordinary Portland Cement (OPC) is the primary ingredient in cementitious mixes and cementitious building materials. OPC is mostly composed of clay and limestone, which harden hydraulically when burned at temperatures above 1450° and crushed into fine cementitious clinker. OPC is blended using both additional natural resources, like pozzolanic clays or limestone filler, and industrial wastes, including fly ashes and slag. (1). Furthermore, a shortage of resources is already a problem in some parts of the world. Additionally, the manufacture of cement alone is responsible for 5–7% of the world's annual CO₂ emissions; one tonne of cement produces 800–1100 kg of CO₂-eq./t (2). Innovative technologies have been developed to reduce carbon emissions. One such technique is carbon capture and storage, which has the potential to be extremely important in mitigating climate change. It involves capturing carbon dioxide that is released during industrial activities, such as the making of cement, moving it, and storing it underground. However, (3) suggested that the environmental impact of cement on the production of concrete is substantial and goes beyond CO₂ emissions and climate change. Polluted water, health concerns from extremely high concentrations of cement kiln dust, and depletion of drinking water supplies are all possible consequences as reduced carbon emissions alone will not be enough to avert the negative consequences.

Supplementary cementitious materials (also known as pozzolanic materials) such as rice husk ash (RHA) according to (4) can increase cementitious material qualities while also lowering building costs. RHA is a kind of agricultural waste that is prevalent in many regions of the world, particularly in rice-growing countries.

Biochar is one of the unique bio-renewable resource technologies that has shown to be a viable solution to the problems associated with biomass-modified cementitious composites.

Furthermore, supplementation of less than 2% of the weight of cement by biochar can be used to make cementitious materials that perform better or equally well as conventional cementitious materials. Assimilation rates can be increased by up to 10% using pretreatment biochar without degrading the characteristics of cementitious composites. (5). Biochar for concrete is pretreated using a variety of techniques to improve its qualities. The application of 0.1 N HCl pretreatment at room temperature has been shown in research by Vikram R. Tirpude to enhance the pozzolanic activity of biochar, increasing its potential for sequestering carbon without affecting the strength of the concrete(6)

Biomass includes materials like sludge, animal dung, waste wood, and living organisms (7). On the other hand, there are limitations to employing biomass compounds as well, for instance increased ash content and longer setting times resulting to a decrease in compressive strength.(8)

This research is aimed at ensuring that appropriate, less costly, and locally available bio-materials reduce dependence on cement and therefore lead to the production of more sustainable building materials that meet the relevant demands. The research in the construction industry is important for economic development based on sustainable construction through low costs and through the reuse of agricultural waste, hence increasing the economic viability of the activities of green practice and reducing the environmental impacts of the activities.

The objectives of the study were (1) to investigate the physical properties of mortar made using rice husk ash and rice husk char, (2) to incorporate agricultural wastes involved in creating a cement replacement from mortars, and more importantly, (3) this study is aimed at developing an environmentally benign approach toward the production of rice husk ash and rice husk char that can contribute to a reduction in the emission of greenhouse gases from cement.

2.1 Production and utilization of biochar’s

Biochar is a black, porous, carbon-rich solid (similar to charcoal) that can be produced by thermochemically converting biomass in the absence of oxygen(9). Biochar has a long history in environmental applications. Pre-Columbian Amazonians used a method involving burning biomass covered with soil to create "terra preta de índio," a dark soil that boosts soil fertility (10). Biochar has some excellent properties including High Porosity and specific gravity (11), Cation Exchange Capacity (12), and high carbon content. The physical characteristics of biochar are directly influenced by both the type of biomass used and the conditions under which pyrolysis occurs, which encompasses any pretreatment and handling of the biomass (13).The nutrient levels in biochar derived from animals might not necessarily surpass those found in biochar derived from plants that have been pyrolyzed at the same temperature (14). According to (10) biochar can be produced by the Direct pyrolysis, Gasification, hydrothermal carbonization, microwave pyrolysis and flash carbonization methods.

Pyrolysis is the process by which organic material is thermally decomposed in an oxygen-deprived state. The output is said to be pyrolytic oil or bio-oil, gaseous components, carbon, and ash residue that are solid in nature. (15). Pyrolysis originated in ancient Egypt to make tar for boat sealing. In North America and Europe, wood-based tar became more significant economically. Pyrolysis yields important byproducts such as methanol and acetic acid in addition to tar. Later, charcoal was produced via pyrolysis and is esteemed for having superior fuel properties to wood. Biochar, is more manageable in smaller amounts, resists decomposition, and generates the same amount of heat with less smoke than wood (16). (17).

Pyrolysis is a versatile technique for producing biochar since it is influenced by various factors, such as feedstock moisture content, pyrolysis residence time, and chimney inclination angle (18). The quality of the biochar is greatly impacted by the temperature during pyrolysis. Higher pyrolysis temperatures mostly result in lower biochar yields, calorific values, carbon content, hydrogen content, and concentrations of some elements like K2O, CaO, P₂O₅, MnO, and TiO₂ according to (19) The pyrolysis reactors have an influence not only on the pyrolysis procedure but also on the structural characteristics of the final biochar carbon. Other than that, the agricultural residues and the process parameters of pyrolysis, including temperature, heating rate, and pressure during the pyrolysis, affect the final chemical composition of the biochar's, as well as physical parameters such as pore size volume, pore size distribution, raw density, and particle sizes. (20). Generally, biomass is pyrolyzed at or above 500°C so that enough heat is available for deconstructing the robust bio-polymers as noted above.

Biochars have been used to enhance the physical properties to improve plant growth (21), In water treatment, biochar’s have been used in in the adsorption of heavy metals such aiding in the process of environmental remediation and water purification (22). In Agriculture, by improving soil fertility, raising crop yields, and securing carbon in the soil, biochar’s are added to soil to support sustainable farming methods (23). Additionally, adding biochar to concrete mixtures can enhance mechanical performance, aid in the carbon sequestration of building materials and, thus, lower the calculated carbon footprint of concrete (24).

2.2 Production and utilization of agricultural waste ashes

The agricultural cycle leaves behind enormous volumes of garbage once harvests are harvested. The major constituents of biomass generated from plants or crops include husks, bagasse, and straws. (25). Agricultural waste, also known as agro-waste, can take on any shape depending on the sort of agriculture that is practiced. It can be liquid, slurry, or solid. It consists of animal excreta and carcasses from livestock farming, crop production residues like corn stalks, and sugarcane bagasse and by-products of food processing industries; for example, if maize is a food crop, then only 20% is used, and the remaining 80% goes as a waste. It also contains poisonous and dangerous materials such as herbicides, insecticides, and pesticides.(26). Production of ash from agricultural wastes has become considerably promising because of environmental problems and urging needs for activities that are less damaging to nature. There is a number of usual agricultural wastes - rice husk, neem seed husk, coconut shell that can be destructive in case they are not effectively well disposed of and managed (27)

Agricultural waste can be put to effective use by production of biogas and biochar, composting and providing a use for animal feed, and production of eco-friendly construction materials. This includes crop residues composting, repurposing of the waste into animal feed, and development into sustainable building material, which will manage waste and maximize on available resources (28). A glaring portrayal is in the use of agricultural waste for developing biodegradable polymers and water purification processes, among others, which point to the importance of recycling agricultural wastes for furthering contemporary green technologies.(29)

Agricultural wastes have been known to contribute directly to the formation of aggregates or ash to be developed into concrete, which will foster eco-friendly construction materials including bio-bricks and lightweight concrete. Additionally, agricultural waste ashes like bio ash can be used for soil amelioration, wastewater purification, and engineering applications with a view to resource efficiency and environmental protection (30). These ashes contain high amounts of silica and alumina, which are important oxides for a majority of their applications. Studies have reported that AWAs, such as rice husk ash and Areca sheath ash, contain 74–92% of silica and moderate alumina (31, 32) Incorporating agricultural waste ashes into building materials, such as cement blocks, actually enhance the properties of these materials further and simultaneously work as a solution to solve the various environmental problems created by the dumping of those wastes in landfills(33). These are the ashes derived from agricultural wastes, which can be put to efficient uses in different applications. They reduce pollution created in the environment and thus ensure sustainability.

2.3 Biochar’s and bio ashes as SCMs

Emerging as prospective supplemental cementitious materials, biochar and bio ashes have the potential to lessen cement production's negative environmental effects.

Incorporating biochar into cementitious composites can help mitigate greenhouse gas emissions by sequestering carbon and reducing the overall carbon footprint of the materials(34).Studies have indicated that the addition of biochar to concrete composites can improve their mechanical characteristics, strength, and water absorption(35), and even support the effective heavy metal removal (36). (37). Consequently, carbon footprint of cementitious building materials and concrete could be reduced by using ashes from agricultural waste as supplement for the aforementioned clinker.(38). On the other hand, physicochemical complexity nature of ashes is a challenge that needs to be faced in their characterization, management before utilization in construction field to harness relevance value and reduce environmental risk (39). Further research is needed in this area to mitigate these challenges and improve the adoption, acceptance, application of bio ashes within construction industry.

Rice husk is an agricultural waste majorly generated at about 20% of the 750 billion tonnes of paddy produced globally. China and India combined generate 70–80 million tonnes of rice husk waste annually(40). Rice husk ash (RHA) comes about by burning rice husks either in open fields or controlled incineration. Open field burning is discouraged because of its harm to the environment and RHA with high carbon content, low reactivity. Controlled incineration produces more reactive RHA, whose structure is influenced by both burn temperature and duration; thus, amorphous silica suitable for use in mortar compared to crystalline silica can be produced under properly-controlled conditions. Indeed, facilitating the production of amorphous silica RHA is important for its performance as a supplementary cementitious material.(4). Extensive research has demonstrated that when rice husks are fully burnt, the resulting ash has a high SiO2 content which ranges from 87–97%. (41).

3.1 Scope of investigation

Therefore, this study aims to obtain biochar and reactive ashes from rice husk; use them as supplementary cementitious materials (SCMs) in mortar thereby improving its physical properties and reducing the environmental pollution due to production of cement as well as agricultural waste management. The objectives of this research work are: investigation of physical properties of mortar with RHA and biochar; testing feasibility of using agricultural waste for partial cement replacement purposes; development of eco-friendly methods for production of RHA and biochar. Chemical composition analyses by X-Ray Fluorescence (XRF) Analysis, crystalline phases determination by X-Ray Diffraction (XRD) Analysis as well as Ultrasonic pulse velocity and compressive strength tests were used to study chemicals components in Rice Husk Ash (RHA) and Biochar so that they could be used as supplementary cementitious materials.

The experimental mixtures vary in RHA and biochar percentages to evaluate their effects on compressive strength, water absorption, and overall mortar performance.

3.2 Equipment and Apparatus Used

3.2.1 Pyrolysis System for Producing Rice Husk Ask (RHA) and Biochar

The locally constructed pyrolysis system consists of the kiln (an insulative membrane made of clay), reactor, condenser, connecting tubes and a collector. The kiln houses the reactor, it serves as an insulator. The system's specifications include the volume capacity of 5369 cm³, the reactor operates at temperatures ranging from 0°C to 800°C and above, depending on the desired properties of the end product, and the system is designed to operate under limited oxygen conditions to facilitate the pyrolysis process rather than combustion. Controlled oxygen supply ensures the conversion of agricultural waste into high-quality RHA and biochar.

This approach is being used because of its circularity, energy efficiency of 75% and above less fuel and retrieving all the by-products in the value chain, without emitting poisonous gases and particulate matter into the atmosphere as compared to the performance of traditional cookstoves.

The RHA and char were broken down into tiny pieces using a pulverizer from the Ceramics department at KNUST; 75 micron-sized mesh was employed to obtain the materials' finer particles. The materials used were measured using an electronic scale. The amount of water to be added to the components was measured using a volumetric flask. Additionally, the materials were stored and stirred in beakers.

3.3 Materials

3.3.1 Cement, sand and water

The sand (Atuabo Sand) was already available at the Ceramic department's laboratory at the Kwame Nkrumah University of Science and technology in its raw, unprocessed state. It was then crushed and sieved into 115 micron-sized mesh The sand has a superior water holding capacity. The cement used was the ‘GHACEM Portland Limestone Cement ‘with a strength grade of 42.5R.

3.3.2 Pyrolysis and Combustion

The initial step involved the pyrolysis of rice husk. This process was carried out at a temperature of 250℃. During pyrolysis, the rice husk was pyrolyzed at a temperature of 250℃, breaking down into a variety of byproducts, including gases, liquids (bio-oil), and solid residues (char). A portion of resulting rice husk char was subjected to a combustion process. This involves heating the char in the presence of oxygen to remove the remaining organic content, leaving behind the inorganic mineral components. The combustion was performed over a temperature range of 400℃ to 700℃. The primary rice husk ash, was attained at a temperature of 700℃.

3.4 Mixture compositions

Table 1

*Mixture Composition of mortars*.
Sample names	Sand (g)	Cement (g)	Ash (g)	Char (g)	Water (g)	w/c (-)	w/f (-)	s/f (-)
A0	750	250	0	0	500	2	2	3:1
A50	750	200	50	0	600	3	2.4	3:1
A100	750	150	100	0	600	4	2.4	3:1
A150	750	100	150	167.9	600	6	2.4	3:1
C50	750	200	0	50	500	2.5	2	3:1
C100	750	150	0	100	500	3.67	2	3:1
C150	750	100	0	150	550	5.5	2.2	3:1

3.5 Chemical analysis and Performance Tests

3.5.2 Chemical Analysis

X-Ray Fluorescence (XRF)

The elemental composition was quantified using XRF for which the RHA, biochar, sand and cement samples were used to make pellets or fused into glass beads. After that, they were put in a sample chamber of a spectrometer. The spectrometer emitted X-rays that bombarded the sample hence causing fluorescence. Secondary x-rays that were emitted by the samples were scanned so as to determine and quantify the elements present. By analyzing data, the chemical composition of RHA and biochar was determined. The analysis was conducted at the Earth science Laboratory, University of Ghana.

X-Ray Diffraction (XRD) Analysis

For mineralogical phase analysis, a high precision XRD diffractometer was used. Fine ground RHA and biochar were pressed into sample holders. The surface was smoothed to ensure even diffraction. These samples were put on a sample stage. From the diffractometer, the samples received X-rays at different angles. Diffracted x-rays were detected and recorded as intensity peaks. The peaks were analyzed for their crystalline/ amorphous phases that existed in them. The analysis was conducted at the Physics Laboratory, University of Ghana.

Ultrasonic pulse velocity

The same procedure of preparation and curing of mortar specimens used during compressive strength testing was followed here. Transducers were attached at either end of the mortar specimens. The immersion gel ensured proper contact. An ultrasonic pulse passed through the specimen of interest. The time taken by this pulse to pass through it gave its thickness. The test was conducted at the civil engineering laboratory, Kwame Nkrumah University of science and technology

3. 5. 3 Performance tests

Compressive Strength Test

The methods for assessing the compressive strength of mortar samples were based on standard procedures. This testing is critical because it determines whether Rice Husk Ash and biochar can be considered viable substitutes for OPC in making cementitious mixes. The mortar test samples were prepared using varying proportions of RHA and biochar in order to evaluate their suitability as a SCM. The mortar samples' biochar and RHA contents ranged from 0–15%, with a 5% increment between each mortar sample. Each test sample contained an equal ratio of sand and "binder" (cement + RHA or biochar) to assure that the supplementary materials could serve in the same capacity as mortar made with just OPC. Water was then added gradually to the dry mix while continuously stirring to form a homogenous mortar. Mortar samples were cast into cube molds, measuring 50 mm x 50 mm x 50 mm. The composition was fed into the molds and compressed to shape using a hydraulic press. The surface of the molds was leveled and smoothed for consistency. The molds were then kept in a humid environment for 3 days to ensure proper setting. Following that, the demolded samples were cured in water for 28 days at a temperature of 20 ± 2°C prior to carrying out any further destructive testing (compressive strength tests).

A universal compressive testing machine capable of exerting loads up to 200 kN, was used for the compressive strength test. Once the curing was complete, the mortar cubes out of the tank and let them dry until the surface moisture was gone. A smoothing technique was used on any irregularities that appeared on the surface of the cubes. Even load distribution during the testing was paramount the cubes were made to be perfectly smooth. The cubes were then placed in the testing machine and was set to apply a load that would increase at a uniform rate. The machine was predetermined to stop when the cube reached its moment of failure. It was then recorded how much load the cube had taken at the point of failure. After that, it was calculated with what the compressive strength of the cube was. The compressive strength was calculated using the formula:

$$\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:{f}_{\left(C\right)}=\frac{F\left(N\right)}{A\left(m{m}^{2}\right)}$$

where: f _c = compressive strength (N/mm²); F = maximum force applied; A = cross sectional area of the specimen.

4.1 XRF analysis

Char, Atuabo sand, RHA, and cement underwent X-ray fluorescence (XRF) studies to ascertain the elemental makeup of the components. The chemical makeup of the main materials used after the X-ray florescence test is shown in the table below. The x-ray florescence equipment was able to determine the element after the RHA was crushed into a very fine powder and shaped into pellets. The main oxides SiO₂, Al₂O₃, Fe₂O₃, and CaO, as well as the minor oxides K₂O and SO₃, were visible when the pellets were put into the x-ray florescence apparatus. Iron, aluminum, and silicon dioxide together made up 96.49% of the mixture, exceeding the > 50% required specified in ASTM (C618-844) for pozzolans. It is therefore a class "C" pozzolans strength booster in the production of mortar. Biochar also contains small amount of Cao, Fe₂O₃,and K₂O the hydration rate, setting time, (5) found that biochar with a greater potassium concentration might speed up the hydration process, which affects the mechanical characteristics of the resultant cementitious materials. This is due to the potassium salt reaction that occurs when cement particles and biochar are in contact during the hydration cycle. Similarly, silica was found in the chemical composition of biochar

Table 2

Elemental composition (wt.%)
Elemental Composition	Cao	Al₂O₃	Fe₂O₃	SiO₂	SO₃	MgO	Na₂O	K₂O
RHA	0.517	0.694	0.196	95.6	-	-	-	1.29
CHAR	2.7	1.68	0.987	89.3	0.9	0.682	-	2.69
ATUABO SAND	0.111	1.17	0.127	97.6	-	-	-	0.0319
CEMENT	54.5	5.77	3.07	23.3	-	6.7	-	1.12

4.2 XRD results

The RHA indicated that amorphous reactive silica predominated, but there was also a very little quantity of crystalline silica (quartz) present. The x-ray diffraction pattern of RHA demonstrating the amorphous phase of rice husk ash is given in Fig. 1. Because it included 95.6% reactive silica, the RHA can be thought of as an amorphous phase.

The char did not produce any sharp diffracting peaks, therefore indicating that amophous silica phases predominated. The x-ray diffraction pattern of CHAR demonstrating the amorphous phase of rice husk a biochar is given in Fig. 2 below.

4.3 Ultra sonic pulse velocity test

Using ultrasonic pulse velocity (UPV) to assess the uniformity and quality of cementitious materials correlates well with the presence of voids and cracks and the effectiveness of repairs. The technique works because sound waves travel well through a dense, uniform medium but encounter resistance and lose energy when they hit a void or crack(42). A pulse velocity of 4500 m/s or higher is indicative of very good quality concrete; a pulse velocity of 3500 to 4500 m/s is indicative of good quality concrete, a pulse velocity of 3000–3500 m/s is considered of good quality ; a pulse velocity of 2000–3000 m/s is considered doubtful, and a pulse velocity of less than 2000 m/s is considered bad quality. (43). All specimens, including the control, 5%, 10%, 15% RHA, and CHAR as shown in the table below, were deemed doubtful.

4.4 Fourier-transform infrared spectroscopy(ft-ir)

FTIR analyses is an analytical technique used to identify organic and polymeric materials. The FTIR analysis method uses infrared light to scan test samples and observe chemical properties. The FTIR test was conducted to determine functional groups of each of the compositions. The FTIR conducted on the samples contained alcohol OH stretch, CH3 bend, N-H stretch and also contained CH2 bend being the functional groups in the sample. These functional groups are highly electrophilic, meaning they accept electrons to form a covalent bond. They have the ability to accept electrons thereby allowing bonding which helps in the compactness of the materials.

4.5 Compressive strength analysis

The compressive strength tests were performed on mortars according to ASTM C109/C109M-20. Flexural strength was tested on three specimens for each mortar type; then, seven samples were obtained which were used for compressive strength testing.

The measured compressive strength of the cubes was calculated by dividing the maximum load applied to the cubes during the test by the cross-sectional area, calculated from the mean dimensions of the section and shall be expressed to the nearest 0.5 N/mm²

The compressive strength test results for the various specimens have been summarized, indicating averages for 21 specimens. The compressive strength of the mortar cubes was tested 28 days after curing was properly done. The compressive strength values of the various compositions and their average are indicated below. Except for the control and 15% compositions, all exhibited a higher compressive strength. The average compressive strength of the control mix is 5.9 N/mm², and for a 5% replacement of cement with RHA, the average compressive strength is 9.2 N/mm². For a 10% replacement of cement with RHA, the average compressive strength of the cubes is 12.1 N/mm², for a 15% replacement of cement with RHA, the average compressive strength of the cubes is 3.0 N/mm², and for a 10% replacement of cement with CHAR, the average compressive strength is 7.2 N/mm², for a 15% replacement of cement with CHAR, the average compressive strength of a cube is 1.9 N/mm², and for a 5% replacement of cement with RHA, the average compressive strength is 6.3 N/mm².

After the testing of the cubes, it was concluded that for the RHA the mortar cube containing 10% replacement had the highest compressive strength followed by 5% and 15% of RHA. For the CHAR the mortar cube containing 10% replacement had the highest compressive strength followed by 5% and 15% of CHAR after 28 days of curing.

The value of the compressive strength of the specimen containing RHA and CHAR as a partial replacement of cement satisfied the criteria of IS 2250 − 1981, i.e., with a minimum compressive strength for 1:3 cube at the age of 28 days of 7.5 MPa and 3 MPa respectively.

Incorporating rice husk ash (RHA) and biochar in cementitious materials provides great benefits to the environment a lot, because it reduces CO₂ emission due to cement production. RHA represents an important amorphous form of silica; it acts as a good supplementary cementitious material contributing to durability and reducing environmental impact. This research demonstrated that 10% of cement replacement with biochar and RHA, respectively, exhibited enhanced compressive strength in their distinguished categories. The reason can be attributed to the pozzolanic reactivity and fine particle size of these materials. This improvement highlights the potential of agricultural wastes to be incorporated in cementitious materials to enhance its mechanical properties

The results of the experiments prove the possibility of the use of RHA and biochar as partial replacements for cement in mortar formulations, which decreases the need for OPC and but also utilizes abundant agricultural wastes, thereby promoting sustainable practices in construction. The use of pyrolysis to produce RHA and biochar under controlled conditions ensures high-quality ash and char suitable for construction applications. This innovative approach enhances the economic viability and environmental sustainability of incorporating agricultural wastes into cementitious blends. The results of the present study are, therefore, far-reaching considering that such agricultural wastes as rice husk are available in abundance across the globe and that current sustainable construction practices in other parts of the world consider the importance of carbon footprint reduction.

The key challenges that must be resolved shortly are optimization of mix designs, variability in waste properties, and permitting in compliance with current building standards. For wide acceptance, additional research is needed to show evidence of material long-term durability and environmental impact. In conclusion, the use of agricultural waste such as RHA and biochar in the cementitious mix offers a promising pathway toward sustainable construction practices, environmental benefits, improved material performance, and, not the least, contributing to global efforts in climate change mitigation, through minimizing CO₂ emissions.

Conflicts of Interest: The authors have no conflicts of interest to disclose.

Data Availability: All relevant data are included within the manuscript.

Authors Contribution: Michael Commeh: conceptualization, supervision, validation, correcting, editing, proofreading of the manuscript. Mareike Thiedeitz: validation, correcting, editing, and proofreading of the manuscript. Benedict Acheampong: conceptualization, funding aquisition, and proofreading of the manuscript. Nkansah Nana Kwame Ashley: writing, methodology, experimental work, analysis, and results interpretation. Godsway Gafah: writing, methodology, experimental work, analysis, and results interpretation. Joshua Mawuli Tsitsi: writing, methodology, experimental work, analysis, and results interpretation. Seth Acheampong: writing, methodology, experimental work, analysis, and results interpretation. Edmond Tsekpo: writing, methodology, experimental work, analysis, and results interpretation. Rosemond Nyamewaa Van Ess: writing, methodology, experimental work, analysis, and results interpretation. Jason Okyeremah Barnor-Arthur: writing, correcting, editing, and proofreading of the manuscript.

Acknowledgement: The authors gratefully acknowledge the support and collaboration of SoulTerra Group throughout this project.

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Utilization of Agricultural wastes as biochar’s and pozzolanic ashes in cementitious blends

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Abstract

Figures

1.0 Introduction

2.0 State of the art: Processing and use of agricultural waste ashes

2.1 Production and utilization of biochar’s

2.2 Production and utilization of agricultural waste ashes

2.3 Biochar’s and bio ashes as SCMs

3.0 Materials and Methods

3.1 Scope of investigation

3.2 Equipment and Apparatus Used

3.2.1 Pyrolysis System for Producing Rice Husk Ask (RHA) and Biochar

3.3 Materials

3.3.1 Cement, sand and water

3.3.2 Pyrolysis and Combustion

3.4 Mixture compositions

3.5 Chemical analysis and Performance Tests

3.5.2 Chemical Analysis

3. 5. 3 Performance tests

4.0 RESULTS AND DISCUSSION

4.1 XRF analysis

4.2 XRD results

4.3 Ultra sonic pulse velocity test

4.4 Fourier-transform infrared spectroscopy(ft-ir)

4.5 Compressive strength analysis

5.0 Conclusion

Declarations

References

Additional Declarations

Status:

Version 1