696 research outputs found
Economic assessment of use of pond ash in pavements
The paper introduces a new type of industrial waste-based subbase material which can replace conventional subbase material (CSM) in pavement construction. Utilisation of this industrial waste, namely pond coal ash produced from a thermal power plant in road construction will help to reduce the disposal problem of this waste and also will help to reduce the problem of scarcity of CSM. Lime and fibre were also added to the pond ash at various percentages to improve the suitability of this type of mix as subbase material. The optimum service life of pavement is studied with the help of numerical modelling and the cost benefit is also presented in the current study. The study reveals that stabilisation of the coal ash with 2% lime may produce an optimal material and, even though a greater thickness may be required to deliver the same pavement performance, direct cost savings of around 10% may be achieved in addition to less easily quantifiable environmental benefits. Design charts are provided to exploit the findings
Geotechnical properties of fiber reinforced pond ash
In the recent past huge amount of Fly ash and Pond ash are generated by the thermal power plants. It is a major cause of concern for the people living around the power
plants. The current rate of deposition of Pond ash in India has reached 170 million tons per annum. About 90,000 acres of precious land is used for the storage of abandoned
Pond ash. But current rate of utilization of ash is only about 35-40%.The unused ash leads to an ever increasing ponding area for storing ash and related environmental
issues for the people around the power plants.
Besides this, over the last few years, the construction of highways and roads has taken a boost. This requires a huge amount of natural soil and aggregates to excavated or to
be deposited. Again this is an environmental issue and economical too. These are some issues now-a-days which motivates in development of alternative methods to overcome
those environmental and also the economic issues. This leads to the reuse of suitable industrial byproducts which can fix those issues and also fulfill the specifications. Pond ash is one such byproduct. It is a non-plastic and lightweight material. During this work, the effect of moisture content, degree of compaction, synthetic fiber
as a reinforcement etc. on various geotechnical properties of pond ash are studied. A series of tests such as direct shear test, CBR test, light compaction as well as heavy
compaction test, Unconfined compression test are done to estimate the strength characteristics of compacted pond ash using synthetic fiber as a reinforcement as well as
tests like specific gravity test, grain size distribution test by mechanical sieve analysis and hydrometer test etc. are performed to obtain some physical properties of the pond
ash.These results will be very much helpful for the successful application of pond ash in different fields such as embankment construction, road base and sub-base construction, designing of retaining walls etc. as well as the disposal of pond ash in an ecofriendly manner
Strength characteristics of fibre reinforced compacted pond ash
At present about 130 million tonnes of ash is being produced annually from the coal based thermal power plants in India. The power requirements of the country are rapidly increasing in pace with in industrial developments. Nearly, 73% of India’s total installed power generation capacity is thermal of which coal based generation are nearly 90% (by diesel, wind, gas and steam adding about 10%). Indian coal gives 35 to 45% ash which is responsible for large volumes of pond ash. Construction of large ash disposal areas results in resettlement issues and loss of agricultural production, grazing land and habitat as well as other hand use impacts from diversion of large areas of land to waste disposal. The current practice in most of the power plants is to use large ash ponds, and nearly 75,000 acres of land is presently occupied by ash ponds sometimes in excess of 80,000 acres, which usually involves resettlement issues. Since, land holdings are typically small in size; a large ash pond development can cause hardships through loss of land-based subsistence and livelihood for literally thousands of people.
Considering these factors, effective utilization of pond ash in geo-technical constructions as a replacement to conventional earth materials needs special attention. The inherent strength of the compacted pond ash mass reduces considerably due to saturation. In this context to improve and retain the strength of compacted pond ash, cementing agents like cement or lime may be very much beneficial. The stress-strain behavior of compacted pond ash mass can be modified by inclusion of fibre reinforcements. Fibre reinforcements also improve the strength characteristics of the mass. Although, the use of reinforced earth materials has been widely accepted in many areas like embankments, foundations medium, railroads, retaining walls but the utilization of pond ash in place of earth material has not drawn much attention of researchers.
The present work aims at evaluating the geo-engineering properties of compacted pond ash and also the effectiveness of fibre inclusions in the strength characteristics of compacted pond ash specimens through a series of shear test, unconfined compression test and CBR test. For this purpose, a polyester fibre (Recron-3s) of 6mm and 12mm in length size is used with the pond ash, collected from Rourkela Steel Plant (RSP). The fibre content was varied as 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.75, and 1.0% of the dry weight of pond ash. The effect of fibre reinforcement on compacted density has been studies using the light and heavy compaction test. Compressive strength and shear strength behaviour of compacted samples were studied using unconfined compressive strength test and direct shear test respectively. The suitability of compacted pond ash fibre mixes as a road base and sub-base material have been studied by conducting laboratory CBR tests. The results have been interpreted in terms of stress-strain behavior, variation of failure stress, variation of failure strain, effect of degree of saturation, effect of fibre content, strength ratio, and secant modulus and strength parameters and are presented in this thesis.
Based on the experimental findings the following conclusions are drawn:
The pond ash consists of grains mostly of fine sand to silt size with uniform gradation of particles. The specific gravity of particles is lower than that of the conventional earth materials.
An increase in compaction energy results in closer packing of particles resulting in an increase in dry density where as the optimum moisture content decreases.
Dry unit weight of compacted specimens is found to change from 10.90 to 12.70kN/m3 with change in compaction energy from 357 to 3488kJ/m3, whereas the OMC is found to decrease from 38.82 to 28.09%.
Both the unit cohesion and angle of internal friction increase with increase in compaction energy. A nonlinear relation between these parameters is found to exist with compaction energy.
For unreinforced compacted pond ash specimens, the value of unit cohesion increases with degree of saturation up to the OMC and thereafter the same decreases. The highest value of unit cohesion occurs at OMC for samples compacted both at standard and modified densities. However, there is a continuous decrease of angle of internal friction value with degree of saturation. Initially there is a sharp decrease which gets stabilized at moisture contents higher than OMC.
The unit undrained cohesion of reinforced specimens is found to increase with the fibre content. However, the rate of increase of unit undrained cohesion with fibre content is not linear. Initially the rate of increase is high thereafter the increase in unit cohesion is not that prominent.
For a given compacted density and fibre content, the 12mm size fibre gives higher strength than 6mm size fibres.
The highest value of unconfined compressive strength is found to be 12kPa and 29kPa at a degree of saturation of 13% and 14 % for samples compacted at standard and modified proctor density. Moisture content either higher or lower than the said value results in decrease in the compressive strength.
The failure stresses as well as initial stiffness of unreinforced samples, compacted with greater compaction energies, are higher than the samples compacted with lower compaction energy. However the failure strains are found to be lower for samples compacted with higher energies. The failure strains vary from a value of 0.75 to 1.75%, indicating brittle failures in the specimens.
An almost linear relationship is found to exist between the compaction energy and unconfined compressive strength.
The UCS value of unreinforced specimens is found to change from 1.2 to 17.0kPa with change in compaction energy from 357 to 3488kJ/m3 indicating that the strength can be modified suitably by changing the compactive effort. It revealed from the test results that a linear relationship exists between the initial tangent modulus with unconfined compressive strength and deformation modulus.
The trend observed in the CBR value with moisture content is very much similar to that observe with unconfined compressive strength value of specimens. This shows that for a given compacted dry density higher unconfined compressive strength as well as CBR value can be obtained with moulding water content much lower than the OMC value.
At low strain levels the bearing resistance is found to remain almost constant with fibre content. However at higher strain level the bearing resistance is found to increases substantially with increase in fibre content. It is observed that for a given compacted density an increase in fibre content results in decrease of initial stiffness whereas the failure strain increases.
The inclusion of fibre gives ductility to the specimens. The reduction in post peak stress of a reinforced sample is comparatively lower than the unreinforced sample.
The strength parameters achieved in the present study is comparable to the good quality, similar graded conventional earth materials. Hence, it can be safely concluded that reinforced pond ash can replace the natural earth materials in geo-technical constructions
Concrete in the low carbon era:proceedings of the International Conference held at the University of Dundee, Scotland, UK on 9 - 11 July 2012
Investigation on the glass fiber reinforced geopolymer concrete made of M-sand
This research work investigates the effect of utilization of glass fibers in geopolymer concrete made of Manufactured sand (M-sand) over its fresh and hardened properties and understand the influence of fibers over reducing the brittleness of the matrix. Geopolymer concrete synthesized in this study is Fly ash- GGBS blend type with optimum molarity cured under heat condition. Fresh property of the fiber reinforced geopolymer concrete was accessed using compaction factor test. Mechanical properties such as compressive strength, split tensile strength, flexural strength, impact strength, ductility factor, first crack toughness, failure crack toughness and ultimate failure toughness were measuredand their results are analyzed and discussed in this work. Later, SEM analysis was carried out over the optimum fiber reinforced geopolymer concrete samples to understand the bonding and the effectiveness of the fiber reinforced geopolymer concrete made of M-sand. Incorporation of glass fiber s proved to be more beneficial and yielded a hybrid concrete with increased strength properties. The performance of fiber s could be measured precisely in increasing the ductility and impact strength. Scanning Electron Microscopy (SEM) analysis showed better bonding between the fiber s and the matrix. This study unleashes an enormous scope for the practical implication of fiber reinforced geopolymer concrete as a building material
Research on Chloride Penetration Resistance of Hybrid Fiber Reinforced Self-Compacting Concrete
The properties of chloride penetration of hybrid fiber reinforced self-compacting concrete (SCC) were investigated in this study. The results show that, the chloride penetration resistance of concrete can be improved by single incorporation either carbon or cellulose fibers. The concrete chloride diffusion coefficient DRCM of 12-cm length carbon SCC with fiber content of 1.7 kg/m3, 2.72 kg/m3, and 3.4 kg/m3 decreases by 10.3%, 25.5%, and 18.2% compared to reference concrete without any fibers, respectively. Moreover, the concrete chloride diffusion coefficient DRCM of cellulose SCC with fiber content of 1.2 kg/m3, 1.6 kg/m3, and 2.0 kg/m3 decreases by 18.8%, 22.4%, and 26.7% compared to reference concrete, respectively. Based on the results of orthogonal experimental design, the chloride diffusion coefficients DRCM of hybrid fiber reinforced SCC are listed in order of importance, as follows: length of carbon fiber \u3e content of carbon fiber \u3e content of cellulose fiber; furthermore, the hybrid of 2.72-kg/m3 carbon fiber with length of 12mm and 2.0-kg/m3 cellulose fiber exhibits the most significant effect on chloride diffusion coefficients DRCM of SCC
Influence of Random Reinforcement on Strength Properties of Fly Ash
Soil reinforcement is a successful and solid procedure for expanding the quality and strength of soils. The system is utilized today as a part of a mixture of uses running from holding structures and banks to sub level adjustment underneath footings and asphalts. In correlation with methodically strengthened soils, arbitrarily appropriated fiber reinforced soils display a few favorable circumstances. Arrangement of arbitrarily disseminated fiber strengthened soils speaks to soil adjustment by admixture. Discrete filaments are essentially included and blended with the dirt, much like concrete, lime, or different added substances. In current study strength analysis of fly ash reinforced with two types of fibers separately, is done. Recron fiber and Coir fiber are used as reinforcement of different length and quantity varying from 0.2 % to 2 %.Thus reinforced fly ash samples are prepared and tested. Based on the findings of the present investigation the main conclusion arrived was Both Coir and Recron fibers are effective in increasing the strength of the compacted fly ash. This also modifies the stress-strain behavior of the mass.Increase in fiber content by mass causes increase in strength. In case of using coir fiber as reinforcement material, when the length of the fiber is increased, there is an increase in strength as well. Samples prepared under modified proctor conditions tests to show more strength than the samples prepared under standard proctor conditions at same fiber content
Potential Usage of Rice Husk Ash-Cement Based Soil in Subbase and Base Courses in Road Construction
This paper presents an experimental study of rice husk ash-cement-based soil for layers in roadway construction. Rice husk ash (RHA) used in this study is a by-product of rice milling. In this work, twelve proportion mixes were used in this work with varying quantities of RHA (0-30%) and Portland cement blended amounts of 4, 6, 8%. The specimens were prepared by the Proctor mould method, conditioned at room temperature, and tested in soaked and unsoaked conditions. Specified curing periods of 7, 14, 28 days were applied for all types of specimens. Some engineering tests were carried out such as proctor compaction, unconfined compressive strength, splitting tensile strength, and the stiffness of stabilized soil. Test results indicated a general decrease in the maximum dry density (MDD) and increased optimum moisture content (OMC) with an increase in RHA content. Adding cement and RHA significantly improved the geotechnical properties of stabilized soils, including compressive strength, splitting tensile strength, elastic modulus. In addition, the combination of 80% soil and 20% RHA and 6% cement can be used as the optimum proportion which satisfied the grade 3 of soils stabilized with inorganic adhesive substances, chemical agents, or reinforced soil for road construction, as indicated in the current Vietnamese standard
Potential Usage of Rice Husk Ash-Cement Based Soil in Subbase and Base Courses in Road Construction
This paper presents an experimental study of rice husk ash-cement-based soil for layers in roadway construction. Rice husk ash (RHA) used in this study is a by-product of rice milling. In this work, twelve proportion mixes were used in this work with varying quantities of RHA (0-30%) and Portland cement blended amounts of 4, 6, 8%. The specimens were prepared by the Proctor mould method, conditioned at room temperature, and tested in soaked and unsoaked conditions. Specified curing periods of 7, 14, 28 days were applied for all types of specimens. Some engineering tests were carried out such as proctor compaction, unconfined compressive strength, splitting tensile strength, and the stiffness of stabilized soil. Test results indicated a general decrease in the maximum dry density (MDD) and increased optimum moisture content (OMC) with an increase in RHA content. Adding cement and RHA significantly improved the geotechnical properties of stabilized soils, including compressive strength, splitting tensile strength, elastic modulus. In addition, the combination of 80% soil and 20% RHA and 6% cement can be used as the optimum proportion which satisfied the grade 3 of soils stabilized with inorganic adhesive substances, chemical agents, or reinforced soil for road construction, as indicated in the current Vietnamese standard
A comprehensive study on the impact of human hair fiber and millet husk ash on concrete properties: response surface modeling and optimization
Revolutionizing construction, the concrete blend seamlessly integrates human hair (HH) fibers and millet husk ash (MHA) as a sustainable alternative. By repurposing human hair for enhanced tensile strength and utilizing millet husk ash to replace sand, these materials not only reduce waste but also create a durable, eco-friendly solution. This groundbreaking methodology not only adheres to established structural criteria but also advances the concepts of the circular economy, representing a significant advancement towards environmentally sustainable and resilient building practices. The main purpose of the research is to investigate the fresh and mechanical characteristics of concrete blended with 10–40% MHA as a sand substitute and 0.5–2% HH fibers by applying response surface methodology modeling and optimization. A comprehensive study involved preparing 225 concrete specimens using a mix ratio of 1:1.5:3 with a water-to-cement ratio of 0.52, followed by a 28 day curing period. It was found that a blend of 30% MHA and 1% HH fibers gave the best compressive and splitting tensile strengths at 28 days, which were 33.88 MPa and 3.47 MPa, respectively. Additionally, the incorporation of increased proportions of MHA and HH fibers led to reductions in both the dry density and workability of the concrete. In addition, utilizing analysis of variance (ANOVA), response prediction models were created and verified with a significance level of 95%. The models’ R2 values ranged from 72 to 99%. The study validated multi-objective optimization, showing 1% HH fiber and 30% MHA in concrete enhances strength, reduces waste, and promotes environmental sustainability, making it recommended for construction
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