International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 12 Issue: 05 | May 2025 www.irjet.net p-ISSN: 2395-0072
Investigation of The Mechanical Properties of Concrete With And Without the Addition of The Rice Husk Ash As An Additive
Anish Baral
Undergraduate Student, Civil Engineering Department, Oxford College of Engineering and Management, Nepal
Abstract - The potential of using rice husk ash (RHA) in substitution of some of the cement in M35 grade concrete is investigated in this study. The goal is to preserve or improve concrete's performance while lessening cement's negative environmental effects. RHA was usedatweightpercentages of 5%, 10%, 15%, and 20% in place of cement. Compressive strength (CS) and flexural (FS) were tested at 7, 14, and 28 days, and workability was assessed using the slump test. Results show that the optimal performance was achieved at 15% RHA replacement, which provided higher compressive (46.5 N/mm²) and flexural strength (4.76 N/mm²) compared to control. However, workability reduced as RHA content increased. This indicates that RHA can effectively enhance strength properties if used in controlledproportions. Thestudy concludes that RHA is a viable supplementary cementitious material in concrete production.
Key Words: CompressiveStrength(CS),FlexuralStrength (FS), Slump Test (ST), Specific Gravity (SG), Cement Replacement,SustainableConcrete,PozzolanicMaterial
1. INTRODUCTION
Concrete is the most widely used building material worldwide, and cement is its main binding agent (Aïtcin, 2000).However,themanufacturingofcementhasamajor impactonenvironmentaldeteriorationandCO2emissions. Tocutdownoncementusage,therehasbeenanincreasing interest in investigating supplemental cementitious materials (SCMs) in recent years. One such promising materialisRHA,aby-productofricemillingindustries.RHA isrichinsilicaandpossessespozzolanicproperties,making it suitable for use in concrete (Antiohos, Papadakis, & Tsimas, 2014). This study examines how using RHA in different amounts to partially replace cement affects the qualitiesofconcretebothwhenitisfreshandwhenithas hardened.
2. OBJECTIVES
To examine how concrete's compressive and flexuralstrengthsareaffectedwhenRHAisusedin placeofsomeofthecement.
To assess the workability of RHA-based concrete usingtheslumptest.
Toverifythespecificgravity(SG)ofcementusedin themixes.
3. LITERATURE REVIEW
RHA'shighsilicacontentandpozzolanicqualitieshaveledto yearsofresearchintoitsuseasanadditionalcementitious material. Chopra, Siddique, and Kunal (2015) emphasized that finely ground RHA enhances the durability and impermeability of concrete, making it more resistant to chemical attacks. According to Sathawane, Vairagade, and Kene (2013), adding up to 15% RHA in place of cement enhanced concrete's mechanical properties, especially its compressive strength, while lowering bleeding and segregation. ExperimentsbyBuietal.(2005)showedthat RHAhelpstoimprovetheporestructureofconcrete,which increasesitsstrengthanddecreasesitspermeability.Zahedi, Ramezanianpour, and Ramezanianpour (2015) found that incorporatingRHAincreasedflexuralstrengthandreduced chloridepermeability,especiallywhenusedinproportions less than 20%. These studies support the hypothesis that RHA can be a viable alternative to conventional cement, particularlywhenusedinoptimalamounts.However,itis also widely acknowledged that excessive replacement of cementwithRHAmayleadtoadeclineinworkabilityand strength,primarilyduetohighwaterdemandingnatureand surfacearea.
4. MATERIALS AND METHODS
4.1
MATERIALS
• Cement: OrdinaryPortlandCement(OPC), specificgravity:3.15
• RHA) Finepowderform
• Aggregates: Standard fine and coarse aggregates
• Water: Clean potable water used for mixingandcuring
4.2 CONCRETE MIX DESING
• Concretegrade:M35
• Application of RHAs: 0%, 5%, 10%, 15%, 20% by weightofcement
International Research Journal of
Volume: 12 Issue: 05 | May 2025 www.irjet.net p-ISSN: 2395-0072
• Water-cementratiomaintaineduniformly
• Fivemixdesignations(Mix1–Mix5)basedonRHA percentage Table -1:
4.3 TESTING PROCEUDRE
The performance of RHA-blended concrete was assessed usinganumberofcommonlaboratorytests. Theslumptest, whichmeasuresthefreshconcrete'scompactionandeaseof installation,wasusedtoevaluateworkability. Toseehow concretestrengthchangesovertime,cubeexamples were inspected after seven, fourteen, and thirty-eight days of curing.Inordertodeterminehowtheconcretewillrespond to bending strains, FS tests were also conducted on beam specimens at the same curing times. Using a Le Chatelier flask,thestudymeasuredtheSGofcementbycomparingthe weightofcementinagivenvolumetotheweightofanequal volumeofwater.Theygaveusaclearpictureofhowfresh and hardened concrete behave at different replacement ratesofRHA
5. RESULTS
5.1
Specific Gravity Test
In this investigation, the Le Chatelier flask method was employedtoevaluatethecement'sSG. Acomparisonwas madebetweentheweightofanequivalentvolumeofwater (23.81 g) and the volume displacement of 75 grammes of cement. The specific gravity, as determined by the conventional formula, was 3.15, falling within the typical rangeforOPC.Thevaluewasincludedinthemixdesignto helpdeterminethecorrectamountofeachmaterialinevery concretemix.
5.2 Slump Test
The workability of fresh concrete for varying RHA replacementlevelswasassessedusingtheslumptest. With themaximumslumpvalueof83mm,thecontrolmix(Mix1) demonstratedexceptionalworkability.Asthepercentageof RHAincreased,theslumpvaluedecreased,reaching58mm forMix4(15%RHA).However,Mix5(20%RHA)showeda slight increase in slump to 63 mm. This variation is attributed to the high porous and fineness nature of RHA, which increases the water demand and thereby reduces
workability. Despite the reduction, all mixes maintained acceptableworkabilityforplacementandcompaction.
Table -2: Slump Test
5.3
Compressive Strength Test
To evaluate the strength growth over time with different RHA content, CS was measured at 7, 14, and 28 days. According to the data, strength generally improved when RHAwasraisedby15%. Themaximum28-daystrengthof 46.5 N/mm² was attained by Mix4, which had 15% RHA replacement,outperformingthecontrolmix(Mix1),which had 40.83 N/mm². This improvement is likely due to the pozzolanicreactionofRHAwithcalciumhydroxide,leading toadditionalC–S–Hgelformation.Mix5(20%RHA)showed aslightreductioninstrengthto43N/mm²,suggestingthat beyondacertainlevel,thedilutionofcementitiouscontent beginstoaffectperformancenegatively.
Table -2: Compressive Strength Test
5.4
Flexural Strength Test
TheFSofconcretebeamswastestedat7,14,and28daysto examinehowRHAimpactsthebendingcapacityofconcrete. Likecompressivestrength,flexuralstrengthimprovedwith increasing RHA content up to 15%. Mix4 recorded the highest28-dayflexuralstrengthof4.76N/mm²,compared to the control mix’s 4.47 N/mm². This indicates that RHA contributes to better matrix densification and enhanced bondingwithintheconcrete.Mix5showedaslightdropto 4.59N/mm²,consistentwiththetrendseenincompressive strengthtests.
International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 12 Issue: 05 | May 2025 www.irjet.net p-ISSN: 2395-0072
Table -3: FlexuralStrengthTest
6. CONCLUSION
This study assessed how the properties of M35 grade concrete, whether it was in fresh or hardened state, were affectedwhenRHAwasusedinpartinplaceofcement. The experimentalresultsallowforthedrawingofthefollowing conclusions:
1. In comparison to the control mix, the addition of RHA up to 15% increased both CS and FS. The maximum28-dayCSof46.5N/mm²andFSof4.76 N/mm²weredemonstratedbythemixcontaining 15%RHA(Mix4).
2. Theincreaseinmechanicalperformanceisdueto thepozzolanicactivityofRHA,whichpromotesthe formation of additional C-S-H and densifies the concretematrix.
3. The high surface area and water absorption properties of RHA were the main causes of the slumptest'sfindingthatworkabilitydecreasedas RHA concentration increased. Nevertheless, the slumpvaluesremainedwithinacceptablelimitsfor constructionpurposes.
4. Aslightdecreaseinstrengthwasobservedat20% RHA replacement, indicating that excessive substitutionmaydilutethecementitiousmatrixand negativelyaffectperformance.
REFERENCE
1) Chopra, D., Siddique, R., & Kunal. (2015). Strength, permeabilityandmicrostructureofself-compactingconcrete containingricehuskash.BiosystemsEngineering,130,72–80.https://doi.org/10.1016/j.biosystemseng.2014.12.005
2) Sathawane, S. H., Vairagade, V. S., & Kene, K. S. (2013). Combineeffectofricehuskashandflyashonconcreteby 30%cementreplacement.ProcediaEngineering, 51,35–44. https://doi.org/10.1016/j.proeng.2013.01.009
3)Zahedi, M.,Ramezanianpour, A.A., & Ramezanianpour,A.M.(2015).Evaluationofthemechanical
properties and durability of cement mortars containing nanosilicaandricehuskashunderchlorideionpenetration. ConstructionandBuildingMaterials, 78, 354–361. https://doi.org/10.1016/j.conbuildmat.2015.01.045
4) Aïtcin, P.-C. (2000). Cements of yesterday and today: Concrete of tomorrow. Cement and Concrete Research, 30(9), 1349–1359. https://doi.org/10.1016/S00088846(00)00365-3
5)Antiohos,S.K.,Papadakis,V.G.,&Tsimas,S.(2014).Rice husk ash(RHA)effectivenessincement and concrete asa functionofreactivesilicaandfineness.CementandConcrete Research, 61–62, 20–27. https://doi.org/10.1016/j.cemconres.2014.04.001