Fly Ash Mixtures Research Articles

Evaluation of the Effect of Binary Fly Ash-Lime Mixture on the Bearing Capacity of Natural Soils: A Comparison with Two Conventional Stabilizers Lime and Portland Cement.

This study evaluates a binary mixture of fly ash and lime as a stabilizer for natural soils. A comparative analysis was performed on the effect on the bearing capacity of silty, sandy and clayey soils after the addition of lime and ordinary Portland cement as conventional stabilizers, and a non-conventional product of a binary mixture of fly ash and Ca(OH)2 called FLM. Laboratory tests were carried out to evaluate the effect of additions on the bearing capacity of stabilized soils by unconfined compressive strength (UCS). In addition, a mineralogical analysis to validate the presence of cementitious phases due to chemical reactions with FLM was performed. The highest UCS values were found in the soils that required the highest water demand for compaction. Thus, the silty soil added with FLM reached 10 MPa after 28 days of curing, which was in agreement with the analysis of the FLM pastes, where soil moistures higher than 20% showed the best mechanical characteristics. Furthermore, a 120 m long track was built with stabilized soil to evaluate its structural behavior for 10 months. An increase of 200% in the resilient modulus of the FLM-stabilized soils was identified, and a decrease of up to 50% in the roughness index of the FLM, lime (L) and Ordinary Portland Cement (OPC)-stabilized soils compared to the soil without addition, resulting in more functional surfaces.

Microstructural and Mechanical Characteristics of Alkali-Activated Binders Composed of Milled Fly Ash and Granulated Blast Furnace Slag with µ-Limestone Addition.

Concrete is the most used construction material, needing large quantities of Portland cement. Unfortunately, Ordinary Portland Cement production is one of the main generators of CO2, which pollutes the atmosphere. Today, geopolymers are an emerging building material generated by the chemical activity of inorganic molecules without the Portland Cement addition. The most common alternative cementitious agents used in the cement industry are blast-furnace slag and fly ash. In the present work, the effect of 5 wt.% µ-limestone in mixtures of granulated blast-furnace slag and fly ash activated with sodium hydroxide (NaOH) at different concentrations was studied to evaluate the physical properties in the fresh and hardened states. The effect of µ-limestone was explored through XRD, SEM-EDS, atomic absorption, etc. The addition of µ-limestone increased the compressive strength reported values from 20 to 45 MPa at 28 days. It was found by atomic absorption that the CaCO3 of the μ-limestone dissolved in NaOH, precipitating Ca(OH)2 as the reaction product. SEM-EDS analysis showed a chemical interaction between C-A-S-H- and N-A-S-H-type gels with Ca(OH)2, forming (N, C)A-S-H- and C-(N)-A-S-H-type gels, improving mechanical performance and microstructural properties. The addition of μ-limestone appeared like a promising and cheap alternative for enhancing the properties of low-molarity alkaline cement since it helped exceed the 20 MPa strength recommended by current regulations for conventional cement.

Increasing the Reliability of Formation Factor-Based Transport Property Prediction for High Performance Concrete Mixtures Through Innovative Matching Pore Solution Curing

Recent specifications for concrete bulk resistivity tests (ASTM C 1876 and AASHTO TP 119) recommend a submerged standard (simulated) pore solution (SPS, solution conductivity = 78.74 mS/cm) for curing concrete specimens. The rationale for the bucket test is that immersing concrete specimens in a soak solution similar to their pore solution would eliminate the need to determine pore solution resistivity for calculating the formation factor (FF) of concrete mixtures. However, the thermodynamic modeling predictions of 91-day pore solution concentration (PSC) for eight high performance concrete (HPC) mixtures evaluated in the current study showed SPS to be a close representation only for reference ordinary Portland cement (OPC) and binary silica fume mixtures. In contrast, the average PSC of Class F and Class C fly ash mixtures was approximately 12% to 20% lower and 20% to 40% higher, respectively, than the SPS. Accordingly, an innovative matching pore solution (MPS) curing approach was developed in which mixtures are grouped based on the influence of supplementary cementitious materials (SCMs), that is, their type and replacement levels of the long-term PSC of concrete mixtures and, thereby, cured in a simulated solution matching the average PSC of a particular group. Based on experimental work in the current study, HPC mixtures under MPS demonstrated a lower coefficient of variation (COV) and more comparable (<10% difference) bulk resistivity (BR) and surface resistivity (SR) measurements compared with SPS. Moreover, the MPS improved the reliability in FF determination and FF-based transport property prediction for HPC mixtures, as verified by lower mean absolute error and improved R2 between FF-predicted diffusion coefficients and experimental measurements.

Utilization of fly ash and bottom ash for tailings stabilization

To anticipate the problem of acid mine drainage generation from the tailings, the experiments on the use of fly ash (FA) and bottom ash (BA) were carried out by considering the neutralizing potential contained in these materials. The basic characteristics of the tailings, FA, and BA materials were tested through mineralogy and geochemical test. Geochemical static tests were carried out on various compositions and rates of FA and BA mixtures added to the tailings. Based on the results of these tests and the results of the Toxicity Characteristic Leaching Procedure (TCLP) test, a kinetic geochemical test was carried out using a column to determine the neutralization performance of FA and BA. The results of the quality test of leachate water coming out from the column for 6 weeks test period showed that a mixture of FA and BA with a ratio of 9:1, which was added to the tailings at the rate of 15 kg/ton of tailings was the optimum mixture that could neutralize the acidity formed, and also reduced the Pb and Cu content in the leachate.

Recovered Fly Ashes as an Anthropogenic Raw Material

Poland is a country where the commercial power industry mainly uses coal to produce energy. As a result of energy production processes, by-products of combustion are generated, primarily fly ashes. In Poland, these are mostly obtained from conventional coal combustion boilers. Fly ashes from coal combustion account for 1.2% of all industrial waste generated in Poland. In addition, fly ashes are produced by fluidized-bed boilers. These are classified as a mixture of fly ashes and solid calcium-based reaction waste from flue-gas desulphurization, and constitute almost 2% of Polish industrial waste. This paper describes the amounts of fly ashes generated in Poland and considers activities related to their recovery and disposal. The high recovery levels of fly ashes (about 90%) and fluidized ashes (about 98%) mean that these waste products can also be considered anthropogenic raw materials. The use of these materials in the cement industry is an example of industrial symbiosis. Such usage benefits not only the economy but also the environment and, therefore, society as a whole. To describe the use of recovered fly ashes in cement plants, the authors use the anthropogenicity index, which characterizes the level of technological advancement and the substitutability of primary raw materials for secondary raw materials.

Experimental investigation of the mechanical properties and large-volume laboratory test of a novel filling material in mining engineering

In this paper, a novel filling material was developed that consisted of a coal gangue and fly ash mixture as the main material and a ground slag, quicklime and plaster mixture as the cementing material. Moreover, an auxiliary agent was added as an activator. The test results showed that the optimum composition of the filling material included coal gangue and fly ash at a 2:1 ratio, accounting for 85% of the total mass, ground slag (G), quicklime (Q) and plaster (P) at a 5:3:2 ratio, accounting for 15% of the total mass, an expansive agent content of 0.01%, and a modifier additive content of 1.0%. A large-volume sample (1 m × 1 m × 1 m) was evaulated with this optimized material composition. The experimental temperature, mechanical performance, regeneration strength, and failure characteristics were determined. The results showed that the temperature of the middle part of the filling body was the highest and peaked at 40.2 °C. The filling material had a high compressive strength and exhibited ideal plastic deformation characteristics. The strength could be restored after damage had occurred and the fracture surface was destroyed along a certain angle.

Characteristics, microstructures, and optimization of the geopolymer paste based on three aluminosilicate materials using a mixture design methodology

This study focuses on the application of mixture design as a novel approach to developing a geopolymer paste with optimized mechanical properties. It also aims to utilize the abundance of natural or industrial aluminosilicate precursors through their combination for synthesizing high-performance geopolymers. The synthesis factors studied are kaolin (K), metakaolin (MK), and fly ash (FA) as aluminosilicate sources. Different mixture proportions were prepared by adopting an augmented simplex-centroid design. Twelve geopolymer pastes were synthesized by activating the mixtures with an alkaline solution of sodium hydroxide and sodium silicate. After 28 days of solidification under ambient conditions, the compressive strength (MPa) and bulk density (g/cm3) of the geopolymer samples were measured. The structural and microstructural properties of the raw and elaborated materials were analyzed using a range of physicochemical techniques, including X-ray Fluorescence (XRF) spectroscopy, X-ray Diffraction (XRD), Fourier Transform Infra-Red (FTIR) spectroscopy, Scanning Electron Microscopy combined with Energy Dispersive Spectroscopy (SEM/EDS), and Transmission Electron Microscopy (TEM). The results showed that the compressive strength and bulk density of the geopolymeric pastes ranged from 7.59 to 19.48 MPa and from 1.52 to 1.82 g/cm3, respectively. According to the validated special cubic models and optimization results, the optimum mixture of FA (75 %) and MK (25 %) was found to develop the optimized geopolymer (GPO) paste with the best performance. The optimized geopolymer matrix had a non-porous structure mainly formed by a dense amorphous sodium aluminosilicate gel, which gave excellent mechanical properties (1.82 g/cm3 and 20.80 MPa). The practical application of the results of this study includes the development of an efficient geopolymer paste with excellent mechanical properties that can be employed in construction and civil engineering applications. The significance of this work lies in its potential to reduce environmental impacts and minimize waste disposal by utilizing abundant natural resources and industrial waste in the formulation of practical and efficient products. Overall, this study provides valuable insights into the development of an improved geopolymer paste through the application of a mixture design methodology, which can have a significant impact on the construction and civil engineering industries.

ПРИМЕНЕНИЕ МЕХАНОАКТИВАЦИИ ДЛЯ ПОЛУЧЕНИЯ ГЕОПОЛИМЕРНЫХ МАТЕРИАЛОВ НА ОСНОВЕ ЗОЛООТХОДОВ СЖИГАНИЯ УГЛЯ С ДОБАВКАМИ КАРБОНАТНЫХ МИНЕРАЛОВ

The results of studies on the synthesis of geopolymers based on mechanically activated mixtures of fly ash from Apatitskaya Thermal Power Plant with magnesium, calcium, strontium, and barium carbonates are presented. It has been shown that in terms of geopolymer strength, calcite CaCO3 is the most effective additive to the fly ash. The influence of the carbonate addition to the fly ash on the physical-mechanical properties of geopolymers has been considered from the standpoint of the reactivity of alkaline earth metal carbonates with respect to the alkaline agent.

Waste Clay Brick as a Part Binder for Pavement Grade Geopolymer Concrete

AbstractGeopolymer concrete (GPC) was developed using one-part binders made from a mixture of waste clay brick (WCB) powder, fly ash, and slag in the precursor. Its suitability for use in rigid pavement construction was evaluated based on fresh properties, hardened properties, and durability characteristics. The effects of sealed and unsealed ambient curing and the size of the WCB particles on the strength of the GPC were also examined. Sealed ambient curing significantly increased the strength of the GPC, with longer sealing periods resulting in even stronger concrete. Sealing prevented water loss from the samples and reduced carbonation, protecting the concrete from microcracks caused by dehydration. The GPC created in this study met the basic strength requirements for use in rigid pavement applications, with 28-day compressive strengths above 40 MPa and flexural strengths above 4.5 MPa. All GPC samples had a water absorption of more than 5%, with a maximum of 7.4%. The apparent volume of permeable voids was less than 14%, which is the maximum allowable value for a 40 MPa pavement-grade concrete. The GPC was resistant to abrasion and cyclic wetting and drying, and experienced only a slight reduction in compressive strength after being subjected to these cycles. There were no significant differences in the wearing depth of the top and bottom surfaces of the slabs, indicating better compaction and homogeneity of the mix.

Efficiency comparison of mixture formulations in the stabilisation/solidification of the loess silt contaminated with zinc in terms of mechanical properties

The effectiveness of various types of binders in stabilizing/solidifying (S/S) contaminated soils is strongly dependent on the type of soil and contaminants present. The literature abounds with studies of stabilisation/solidification of clayey soils, which provides a background for initial assumptions in design of the method application for contamination of this type of soil. However, studies on the stabilisation/solidification of loess silt contaminated with heavy metals are not available. Filling this deficiency is important in order to ensure the rapid adoption of the most effective remedies in case of contamination and their immediate implementation in the subsoil. This paper has enabled the determination of the most effective mixture among the examined for the remediation of loess silt contaminated with zinc in terms of compressive strength. Strengths were determined with the implementation of 30% Portland cement (2.63 MPa), 30% of fly ash-cement mixture (2.21 MPa), an incinerated sewage sludge ash-cement mixture (0.93 MPa) and mixtures in which cement was replaced by an MgO activator (0.18 MPa for fly ash and 0.63 MPa for incinerated sewage sludge ash). In addition, the determination of strength was carried out for samples containing a mixture of fly ash, activator and cement (0.26 MPa) and incinerated sewage sludge ash, activator and cement (0.26 MPa), with weight ratios of 5:4:1 respectively. In summary, fly ash and cement in a 2:1 ratio can be considered the most effective binding mix in terms of unconfined compressive strength increase.

Co-vitrification of hazardous waste incineration fly ash and hazardous waste sludge based on CaO–SiO2–Al2O3 system

Based on the CaO–SiO2–Al2O3 system, the feasibility of co-vitrification of hazardous waste incineration fly ash (FA) and hazardous waste sludge (HWS) was verified. In the CaO–SiO2–Al2O3 ternary system diagram, the melting point of the system gradually decreases with an appropriate increase in SiO2 content when the CaO/Al2O3 ratio is determined to be approximately 1. The TG-DSC results revealed that the liquid phase generation temperature in the FA and HWS mixture system was significantly lower than those of FA and HWS individually owing to the different CaO, SiO2, and Al2O3 contents; this is consistent with the results of the theoretical melting characteristics analysis, which show that the melting characteristic temperatures can be reduced by controlling the CaO–SiO2–Al2O3 ratio in the system. The co-vitrification experimental results confirmed that a vitreous content above 92%, a loss ratio on acid dissolution less than 1.74%, and leaching toxicity of heavy metals lower than 0.15 mg/L could be obtained by adjusting the CaO, SiO2, and Al2O3 contents in the FA and HWS system to 20 wt%–32.5 wt%, 35 wt%–61 wt% and 14 wt%–32.5 wt%, respectively, and under a melting temperature of 1350 °C.

Amelioration Effect of Fly Ash and Powdered Ground Steel Slag for Improving Expansive Subgrade Soil

The utilization of fly ash (FA) and powdered granulated steel slag (PGSS) as additives in soil stabilization plays a crucial role in environmental, economic, and weak soil property improving advantages. In this study, the combined effect of FA and PGSS in improving expansive subgrade soil was investigated. The materials used for this study were expansive soils, FA, and PGSS. The study has applied an experimental research method. For this investigation, the index properties, Free Swell Index (FSI), unconfined compressive strength (UCS), optimum moisture content (OMC), California bearing ratio (CBR), and scanning electron microscope (SEM) tests were done for treated and untreated expansive soils. The findings indicated that as the mixture of FA (0 to 12.5% at 5% increment) and PGSS (0 to 25% at 5% at 2.5% increment) is added to the untreated expansive soils, the index properties, FSI, and OMC of the soils were significantly declined. The CBR values of expansive soils containing 20% FA and 10% PGSS mixture were 13.8% and 16.21%, respectively, which improved the quality of the soils by 85.43% and 84.82%, respectively. While the untreated expansive soils have a UCS value of 0.34 kg/cm2, the treated soil comprising 20% FA and 10% PGSS mixture has a UCS value of 13.42 kg/cm2, indicating that the soil strength is enhanced by 97.47%. The results of the studies demonstrate that adding FA and PGSS to expansive soil improves its stability and strength. The study concluded that disposals such as FA and PGSS might be effectively used in enhancing the characteristics of construction materials and used for the construction.

Investigation of the Effects of Mixtures of Fly Ash and Cement Types on Jet-Grout Columns

Investigation of the Effects of Mixtures of Fly Ash and Cement Types on Jet-Grout Columns

Calcium carbide sludge activated fly ash mixture for offshore construction and its crack repair using seawater-mixed bioslurry cement

This paper reports a mixture based on the calcium carbide sludge (CCS) activation of fly ash. The formed calcium silicate hydrate (C–S–H) gel binds sands and gravel particles to synthesize pozzolanic-lime mortars and concretes. In both seawater and tap water, Ca(CO3), Ca(OH)2, and C–S–H were the main phases of hydration, as determined by powder X-ray diffraction. The optimal mixture was obtained using a CCS to FA ratio of 0.8 and curing time of 14 d. The surface morphology of spherical FA in the tap water mixed pozzolanic-lime materials had relatively loose rod-like, flower-like, and block structures, which were different from the irregular and dense block structure in the seawater mixed pozzolanic-lime mixture. For the fiber-reinforced mortar, the optimal content of polypropylene fiber was 0.1%. The surfaces of the fiber reinforced pozzolanic-lime mortars prepared using seawater were more compact than those prepared using tap and distilled water. The strengths of the fiber-reinforced specimens soaked in both seawater and tap water were maintained after 14, 28, 60, 90, and 120 d. The water permeability of pozzolanic-lime mixture with cracks was effectively reduced by spraying a seawater-mixed bioslurry cement. This work demonstrates the potential of a seawater-mixed pozzolanic-lime mortar as an offshore road base material and a bioslurry cement as its crack repairing material.

Experimental Study on Liquefaction Characteristics of Saturated Sands Mixed with Fly Ash and Tire Crumb Rubber

The liquefaction of saturated sandy soils during dynamic loading can inflict excessive damage on the structures, leading to significant human and economic losses. Recycling and reusing industrial waste materials may offer a sustainable and economic solution to this problem. This study investigates the influence of two waste materials, namely, recycled fly ash and tire crumb rubber, on the liquefaction characteristics of sand. For this purpose, loose and medium-dense triaxial specimens were prepared using sand–fly ash mixtures containing 0–40% of fly ash and sand–tire crumb rubber mixtures containing 0–30% of crumb rubber. The liquefaction characteristics of the specimens were examined through a series of stress-controlled, undrained, dynamic triaxial tests. The tests were conducted at 1 Hz loading frequency and under initial effective confining stresses of 50 and 100 kPa. The experimental results showed that, at a similar relative density, the liquefaction resistance of the sand–fly ash specimens decreased as the fly ash content (FA) increased up to about 20%; then, it slightly increased until FA reached 40%. Sand-only specimens showed greater liquefaction resistance than sand–fly ash specimens. The liquefaction resistance of the sand–tire crumb rubber specimens was enhanced by increasing the rubber content (RC) in the mixtures. It was found that the increasing liquefaction resistance of sand with the addition of tire crumb rubber was more noticeable under higher confining stresses.

Effect of Mixing Coffee Husk Ash and as a Cement Replacement on The Strength of Concrete

Concrete is one of the materials used to strengthen structures. In addition, concrete technology is constantly evolving and is most frequently applied in the construction of buildings. As one of the components of concrete, cement has the potential to harm the environment, from the extraction of raw materials through manufacture to ash pollution. Coffee husks, which are abundant in the Takengon area in the Central Aceh district and are particularly festive, are one among the various organic wastes in Aceh. Silica, a key component in the creation of cement, can be found in coffee residue. In this study, the impact of using fly ash and coffee husk ash in place of OPC cement on concrete’s compressive strength was investigated. The research methodology followed SNI 7656-2012 guidelines. Coffee husk ash was baked for five hours at a temperature between 200 and 250 °C with 5%, 10%, and 15% fly ash by weight of OPC cement. There are 24 cylindrical specimens, each measuring 15 cm in diameter and 30 cm in height. Testing was done on concrete that was 7 and 28 days old. The study’s findings include the concrete’s seven-day age and compressive strengths of 0% (12.27 MPa), 5% (10.52 MPa), 10% (9.99 MPa), and 15%. (9, 09 MPa). Compressive strength with percentages of 0% (21.47 MPa), 5% (13.16 MPa), 10% (10.74 MPa), and 15% at the age of 28 days (5.13 MPa). The designed concrete has a compressive strength of 20 MPa at 28 days of age and a percentage of 0% of 21.47 MPa. The results of testing the compressive strength of concrete show that the lower the percentage of the mixture of coffee husk ash and fly ash, the less compressive strength of the concrete. This is because coffee husk ash contains an excessive amount of silica (SiO2), which prevents cement’s reaction with lime and prevents the concrete mixture from having enough water to achieve maximum bonding.

Approach to fly in roadbed cobnstrction

Nowadays, filling sand is mainly used for roadbed construction. However, this material resource is gradually depleting. At the same time, sand has loose grain structure and small elastic modulus (E ≤ 40Mpa) therefore it fails to meet the technical requirements of roadbed construction. Consequently, roadbed is often embanked with alternative materials such as soil reinforced with inorganic binders, natural aggregates, and macadam. leading to high cost and environmental pollution. Therefore, it is important to determine a new type of roadbed material. This study presents several laboratory tests on the mechanical and physical properties of sand mixed with fly ash in order to find an appropriate mixture for roadbed construction. The test results show that the mixture of sand and fly ash, which contains an optimal ratio of sand/fly ash of 70%/30% with a dry volume value of 1.821g/cm³, not only meets the requirements for roadbed materials, but also utilizes more fly ash. When adopting Geopolymer technology where alkaline solution is added to reinforce sand-fly ash mixture with the ratio of sand/fly ash of 70%/30%, fly ash will be activated by the alkaline solution to produce gelatinous material through a series of reactions. The gelatinous material is characterized by the high-strength and the tightly-linked molecules. Apart from being a suitable material for roadbed construction, sand fly ash material can also be used as a foundation layer for pavement structure

Evaluation of fly ash concrete in salt environment

Indonesia is an archipelagic country with many buildings located in the coastal area. Seawater contains 3.5% salt, which can eat away at the strength and durability of concrete. Sodium salts can be dangerous when combined with reactive alkaline aggregates, and the crystallization of salts in concrete cavities can destroy them due to crystallization pressure. Concrete porosity is important to study, especially in beachfront buildings and buildings that intersect with the ground. In Riau Province, several companies operate AMP (Asphalt Mixing Plant) or paved mixture production units, which produce a large amount of fly ash or AMP waste. Research suggests that using only alkaline cement, using only alkaline cement, a mixture of 15% and 20% fly ash, can be more durable than concrete. This study used fly ash additives with seawater curing to determine the compressive strength of concrete with a curing life of 7, 14, and 28 days. This research was conducted because there was limited compressive strength research on concrete using a mixture of fly ash with seawater curing.

Shear strength characteristic of geopolymer fly ash and egg shell powder stabilized clay soil

The clay soil can present various issues as a construction and infrastructure material. Clay soil is susceptible to shrinkage and swelling, limited bearing capacity, poor drainage, and erosion. Several techniques, including soil stabilization, drainage systems, and excavation techniques, may alleviate these issues and control the risks associated with clay soil. There is a growing interest in soil stabilization and developing environmentally friendly alternatives to Portland cement. Alternative utilization of waste with pozzolanic properties as a stabilizing material to replace cement and lime is increasing. In this field, the use of waste materials such as fly ash and eggshell powder is increasing. This study examines the properties of clay soil shear strength treated with a mixture of fly ash and eggshell powder geopolymer. The unconsolidated, undrained triaxial test was performed to determine the shear strength of the treated soil. In addition, the effects of sample variation, such as NaOH molarity, curing duration, and the ratio of eggshell powder to replaced fly ash, were studied. The results demonstrated that 5% eggshell powder might boost the shear strength of treated soil. In addition, increasing the NaOH molarity resulted in higher shear strength values, showing that the geopolymer has a more substantial binding effect. However, extending the curing period impacts the shear strength of stabilized soil. This study established the viability of eggshell powder geopolymer as a stabilizing agent for clay soil. Including 5% eggshell powder in the fly ash geopolymer mixture can enhance the shear strength of the soil.

Hydraulically manufactured cement and fly ash stabilized compressed soil block

This study aimed to assess the suitability of producing Compressed Earth Bricks (CEB) using a mixture of soil, cement, and fly ash as an alternative to traditional bricks that are currently available. The soil used for this study was red soil present in the Mangaluru region and the properties of the soil such as specific gravity, particle size distribution, Atterberg limits were tested. Further, compaction test was carried out on the soil to determine the water content needed for achieving the optimum density. The soil was stabilized using 8% OPC for manufacturing blocks of size 150 mm × 150 mm × 150 mm. The CEB were admixed with 20%, 30%, 40%, 50% and 60% Fly ash by dry weight of cement during casting, thus gradually replacing cement in the soil. Hydraulically operated Compression testing machine of capacity 2000kN was used to prepare the blocks and subsequent testing was also carried out by the same machine. The compressive strength and the water absorption on the 7 varieties of soil blocks were tested at 7 days, 14 days and 28 days curing time. Results revealed that replacement of cement by fly ash by 50% (4% cement and 4% fly ash combination) led to maximum compressive strength in the soil blocks and the average water absorption was 15%. It is concluded that the addition of fly ash in partial replacement to Ordinary Portland Cement (OPC) was effective in reducing the usage of OPC and thus the huge amount of waste generated from power plants will be a small way in reducing the carbon imprint on the planet.