Role of sugarcane biomass ash on the precursor and silicate part-activator phases of geopolymer concrete

Influence of repeated heating–cooling cycles and exposure duration on mechanical, electrical, and durability properties of geopolymer concrete

Sugarcane bagasse ash (SCBA) is a by-product of the sugar factories produced after burning sugarcane bagasse in the production of electricity. The sugarcane bagasse is produced after the extraction of all economical sugar from sugarcane. The disposal of this material is a common environmental problem in factories producing electricity from sugarcane. In Kakira Sugar Limited (KSL) about 61,000 tons / yr. of SCBA is produced and only about 30,000 tons / yr of this is utilized, and the remaining is damped which becomes an environmental hazard. This research was, conducted to examine the potential of bagasse ash as a cement replacing material in construction industry. The idea of using SCBA as a building material has generated additional cash flow for the sugarcane processing mills. Bagasse ash samples were collected from KSL and its chemical properties were investigated. The compressive strength of mortars containing ordinary Portland cement and SCBA in proportions of 0%, 10%, 15%, 20%, 25%, 30% and 40% as a cement replacement were investigated. Three replicates with the bagasse ash replacing ordinary Portland cement in the above mentioned proportions were prepared and tested. The results showed that ordinary Portland cement can be replaced by SCBA up to 20% without affecting the compressive strength of the mortar at a test age of 28 days. These findings suggest that replacement of cement with SCBA could results in the reduction in cost of construction. Hence it can be concluded that it is safe to replace cement with sugar cane bagasse ash up to 20%.

Large amount of waste ash are produced by various industries. Some of the major waste ashes produces by industries include fly ash (FA), ground granulated blast furnace slag (GGBFS), Red mud (RM), ferrochrome slag (FS), Metakaolin (MK). Waste ashes also include agricultural residues like rice husk ash (RHA), sugarcane bagasse ash (SBA)andpalm oil fuel ash (POFA). These waste ashes plays an enormous challenge while it comes to the dumping of these materials. On other hand, conventional cement concrete consumes huge amount of cement which generates huge amount of CO2 during the production phase. To overcome these problems, utilization of these waste materials is necessary. Thus geopolymer concrete has been developed as a substitute to conventional cement concrete, where alkali activators react with the binder along with fine and coarse aggregates. The binder for geopolymer concrete can be any industrial or agricultural wastes which are rich in silica and alumina that collectively not only lead to the reduction in the environment pollution and waste management problem but also in enhancement of the properties of concrete. The purpose of this paper is to review the durability performance (like Sorptivity, Water absorption, Acid attack, Chloride attack, Wetting-drying cycles) of geopolymer concrete utilizing waste materials like FA, GGBFS, MK, VA, POFA, RM, FS, SBA and RHAetc. as binder to determine its suitability in the construction industry. The durability of geopolymer concrete utilizing fly ash and slags as binder have shown good resistance than other binder combinations and therefore proves to be better replacement to the conventional cement concrete.

This research aimed at exploring the effects of a mixture of sodium hydroxide (NaOH) and potassium hydroxide (KOH) activators in a sugar cane bagasse ash (SCBA)-based geopolymer cement paste. Bagasse ash replacement was 20% of cement by weight. The mixture of NaOH and KOH comprised 4, 8, and 12 M solutions with mixing percentages of 0%, 20%, 40%, 60%, 80%, and 100% for all possible combinations. A pH test was performed on each possible combination of solutions. A Chapelle’s test, XRD, X-ray fluorescence (XRF), and SEM analysis were used to check whether the SCBA exhibited pozzolanic reactivity. Subsequently, the SCBA geopolymer cement paste was tested for compressive strength, water absorption, permeable porosity, and sorptivity. It was estimated that the geopolymer cement paste exhibited higher absorption and sorptivity values than control mixtures when molarity increased. However, the samples prepared with combinations of the 8 M activator solution exhibited consistent absorption, sorptivity, and compressive strength values when compared to the control and other geopolymer mixtures with 4 and 12 M activator solutions. Thus, the two activator solutions G8N408K60 and G8N208K80—where GxNayKb represents the geopolymer concrete sample prepared by adding solutions of two bases, i.e., ‘xNayKb’ showing an ‘a’ percentage of ‘x’ molar NaOH and a ‘b’ percentage of ‘y’ molar KOH—were obtained as the optimum molar ratio of the activator in geopolymer concrete. The geopolymer cement pastes, along with the optimum and control samples, were further tested for concrete durability, SEM, and TGA tests. The G8N208K80 sample exhibited a better mechanical and durability performance than the G8N408K60 sample. The durability performance of the geopolymer concrete was also superior to ordinary concrete. Moreover, the geopolymer concrete achieved a 21% reduction in global warming potential compared to the control mixture. Thus, it can be concluded that the use of SCBA in geopolymer concrete can address the ash disposal and CO2 emission problems with enhanced durability.

The construction industry has been struggling to reduce its carbon emission, and hence the pressing interest in exploring low-carbon alternatives to conventional cement-based products. A sustainable solution is geopolymer concrete (GPC) which exploits industrial and agricultural by-products. This present research explores the viability of replacing a part of fly ash in a GPC mixture with sugarcane bagasse ash (SCBA). The binder system is made of 70% fly ash (FA) and 30% ground granulated blast furnace slag (GGBFS), which are used in combination with 8 and 10 molar alkaline solutions. The SCBA is substituted with fly ash in 5%, 10%, 15%, 20%, and 25%. Twelve mixes are tested on workability, strength, and durability properties. The findings indicated that at 15 percent replacement of SCBA exhibited the most favourable performance in mechanical strength characteristics. The highest 28-day compressive strength achieved is 41.76 MPa in the mix that includes 10 M alkaline solution and 15% SCBA. Furthermore, it was concluded that the interior structure is more compact and refined in comparison to other mixtures. The findings substantiate that SCBA may be efficiently utilized in geopolymer concrete to minimize carbon footprint while ensuring high performance.

Mechanical Strength and Microstructure of GGBS-SCBA based Geopolymer Concrete

Geopolymer concrete (GPC) became the substitute for conventional Portland cement-based concrete in recent years. In this work, fly ash (FA) and sugarcane bagasse ash (SBA) are used to create geopolymer concrete. The percentages of fly ash replacement with SBA at 0%, 10%, 20%, 30%, 40%, and 50%, respectively, are indicated by the designations FS0, FS10, FS20, FS30, FS40, and FS50. Whereas FS0 indicates the traditional mix with no fly ash replacement, FS50 indicates a 50% replacement of fly ash. Compressive strength, flexural strength, and split tensile strength were among the mechanical characteristics that were tested. At 12 M NaOH, the geopolymer concrete FS30 had compressive strengths of 46.88 MPa after 28 days. This effect is consistent with fly ash’s geopolymerization reaction, which helps to generate more binding phases and produces denser and stronger concrete. Random forest (RF) algorithm demonstrated the most robust performance, achieving strong testing R² values of 0.8368, 0.7861, and 0.8199 for compressive, flexural, and split tensile strength, respectively. In contrast, the XGBoost model was, evidenced by its near-perfect training R² scores of approximately 0.9999, which plummeted to significantly lower testing R² values of 0.7378, 0.7136, and 0.7140 for the three strength properties. Similarly, the ANN also showed with high training R² values around 0.94, but a poor ability to generalize, resulting in considerably lower testing R² values of 0.4836, 0.5199, and 0.5424.

Exploring nonconventional cementitious materials is vital for enhancing material performance, reducing construction industry's environmental footprint, and promoting sustainable resource management. This study investigated the potential of minimally processed sugarcane bagasse ash (SCBA) as a supplementary cementitious material in mortar mixes, examining its effects on compressive strength, ultrasonic pulse velocity, density, water absorption, and microstructure. Notably, the SCBA used in this study was processed with minimal energy input, involving only sun drying, coarse sieving through a 150-μm mesh, and gentle oven drying to remove residual moisture. In this view, seven cementitious mixes were prepared, comprising a control mix and six mixes with SCBA replacement levels ranging from 5 % to 30 % by weight of binder (Cement + SCBA). Initially, the 7-day compressive strength decreased with increasing SCBA replacement, whereas 28-day strength increased for mixes containing 5–15 wt% SCBA, with a maximum 12.67 % increase at 5 wt% replacement, and all mixes up to 15 wt% SCBA met ASTM C270 specifications. Up to 5 wt% SCBA substitution enhanced both ultrasonic pulse velocity (UPV) and density, but further additions led to decreased UPV and density values due to the formation of a porous microstructure resulting from increased SCBA content. However, despite this decrease, mortars containing up to 15 wt% SCBA achieved UPV values surpassing the literature-defined thresholds for good (3500 m/s) and excellent (3800 m/s) quality cement mortar at 28 days, indicating yet a well-packed microstructure. The incorporation of upto 15 wt% SCBA resulted in reduced water absorption at 28 days, meeting the requirements of ASTM C62. A quadratic regression model was employed to investigate the relationship between SCBA content and mortar properties, including compressive strength, ultrasonic pulse velocity, density, and water absorption. The analysis revealed a statistically significant fit (p < 0.05) with a high coefficient of determination (R2 > 0.90), indicating a strong relationship between SCBA content and mortar properties. Microstructural evaluation confirmed beneficial effects of SCBA incorporation on mortar morphology, within moderate dosage ranges (up to 15–20 wt% SCBA). The study highlights the potential of using energy-efficient SCBA as a sustainable supplementary cementitious material to improve mortar mix performance and contribute to the development of environmentally friendly cementitious materials.

Biomasses are organic materials that are derived from any living or recently-living structure. Plenty of biomasses are produced nationwide. Biomasses are mostly combusted and usually discarded or disposed of without treatment as biomass ashes, which include wood and sugarcane bagasse ashes. Thus, recycling or treatment of biomass ashes leads to utilizing the natural materials as an economical and environmental alternative. This study is intended to provide an environmental solution for uncontrolled disposal of biomass ashes by way of recycling the biomass ash and replacing the soils in geotechnical engineering projects. Therefore, in this study, characteristic tests of wood and sugarcane bagasse ashes that are considered the most common biomass ashes are conducted. The test of chemical compositions of biomass ashes is conducted using energy dispersive X-ray spectroscopy (EDS), and Scanning Electron Microscope (SEM), and heavy metal analysis is also conducted. Engineering behaviors including hydraulic conductivity, constrained modulus and shear modulus are examined. Also, coal fly ash Class C is used in this study for comparison with biomass ashes, and Ottawa 20/30 sands containing biomass ashes are examined to identify the soil replacement effect of biomass ashes. The results show that the particle sizes of biomass ashes are halfway between coal fly ash Class C and Ottawa 20/30 sand, and biomass ashes consist of a heterogeneous mixture of different particle sizes and shapes. Also, all heavy metal concentrations were found to be below the US Environmental Protection Agency (EPA) maximum limit. Hydraulic conductivity values of Ottawa 20/30 sand decrease significantly when replacing them with only 1%–2% of biomass ashes. While both the constrained modulus and shear modulus of biomass ashes are lower than Ottawa 20/30 sand, those of mixtures containing up to 10% biomass ashes are little affected by replacing the soils with biomass ashes.

This study explores the durability of green cementitious material of geopolymer concrete. Geopolymer concrete is produced from the polycondensation reaction of aluminosilicate materials (fly ash, Ground Granulated Blast furnace Slag (GGBS)) with alkaline activator solutions. Geopolymer concrete has excellent mechanical properties and its production requires low energy and results in low levels of CO2 emission. Due to the high demand for river sand, manufactured sand is used as a replacement material in geopolymer concrete under ambient curing conditions. In this study, the durability of G30 grade geopolymer concrete has been investigated using tests acid resistance, water absorption, sulphate resistance, Rapid Chloride Penetration Test (RCPT), and rate of absorption (Sorptivity) test. The sulphuric acid, sodium sulphate, and water absorption tests were carried out at 28 days, 56 days, and 90 days for both the geopolymer and the conventional concrete. The reduction percentage in water absorption and compressive strength loss was found to be better in geopolymer concrete than in conventional concrete. Geopolymer concrete’s chloride penetrability and rate of absorption were analogous to conventional concrete. Regression analysis for geopolymer and conventional concretes in the rate of absorption test showed a good relationship between absorption and the square root of time.

The reduction of the carbon footprint and the preservation of natural raw materials in the construction industry is crucial for the improvement of the environment. Geopolymer is a novel approach that has recently come to the limelight for sustainable and greener construction development due to its lower greenhouse gas emissions. This study focuses on utilizing industrial waste products like Ground granulated blast furnace slag (GGBS), Sugarcane bagasse ash (SBA), and Micronized biomass silica (MBS) for the production of geopolymer concrete. The geopolymer concrete’s performance is assessed by testing various combinations of materials at different percentages to measure compressive and flexural strength, water absorption, water sorptivity, Rapid Chloride ion Penetration test (RCPT), carbonation, resistance to acid attack, and characteristics studies. The results revealed that the combination of 10% of SBA and 8% of MBS on GGBS-based geopolymer improves strength and durability compared to the control mix. The role of MBS has been highlighted, which serves its purpose by densifying the matrix by extending C-S-H gel formation and filling voids caused by incorporating SBA, which is validated through characterization studies—feasibility of agro waste in the geopolymer production.

Biomass ashes from agricultural wastes as supplementary cementitious materials or aggregate replacement in cement/geopolymer concrete: A comprehensive review

One of the main staples in the construction industry is Portland cement-based concrete, which currently contributes to 8% of global CO2 emissions during cement production. In this respect, the geopolymer technology shows considerable promise for application in the concrete industry as an alternative binder to Portland cement. Still, there has not been a significant shift away from the use of Portland Cement due to the demand for additional necessary precautions and the requirement of high temperature to bring about rapid strength gain. The mechanical and durability properties of class F fly-ash (FA), based Alkali Activated Concrete (AAM) with varying percentages of Ground Granulated Blast Furnace Slag (GGBS), Rice Husk Ash (RHA), and Sugarcane Bagasse Ash (SCBA) cured at ambient weather conditions are discussed. The results of the tests further indicate the possibility of using ambient cured AAM Concretes for construction purposes.KeywordsFly ashGround Granulated Blast Furnace Slag (GGBS)Geopolymer Concrete (GPC)Rice Husk Ash (RHA)Sugarcane Bagasse Ash (SCBA)Agricultural wasteSustainable concreteConcreteAlternative construction materials

Environmental impact assessment of fly ash and silica fume based geopolymer concrete

Rheological properties of cement paste blended with sugarcane bagasse ash and rice straw ash