Investigating Optimum Conditions for Developing Pozzolanic Ashes from Organic Wastes as Cement Replacing Materials (original) (raw)
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Evaluation of Rice Straw Ash as a Pozzolanic Addition in Cementitious Mixtures
Applied Sciences
Rice husk ash is one of the most widely studied biomass ashes used in pozzolanic addition. Given its lower silica content, rice straw ash (RSA) has been explored less often, despite the fact that, according to the United Nations Food and Agriculture Organization (FAO), rice straw (RS) production is estimated at 600 million tons/year. In this work, RSA was physically and chemically characterized, and its pozzolanic properties were assessed. A controlled conditioning, burning, homogenization and grinding procedure was carried out to obtain RSA from RS. Chemical composition, insoluble residue, reactive silica, chloride content and particle size distribution were assessed for ash characterization. To determine RSA pozzolanicity, Frattini, electrical conductivity and pH measurements in an aqueous suspension of hydrated CH/RSA mixtures were obtained. Portland cement (PC) mortars with 15% and 30% RSA substitutions evaluated. The mechanical tests showed specimens with a strength activity in...
Crimson Publishers LLC, 2020
In this research work a synthetic review of the quantitative characterization of various materials (sugar cane waste ashes, bamboo leaf ash, calcined paper sludge, loessic soils, zeolite, fly ash and silica fume) based on the computing of the kinetic parameters of the pozzolanic reaction in pozzolan/calcium hydroxide(CH) systems is offered. The paper presents of more relevant results in the quantitative characterization (computing of the kinetic parameters) of the pozzolanic reaction of different materials originated from agriculture, mining or industry activities carried out by the authors.Two pozzolanic activity tests (conductometric method and accelerated chemical method) are employed. A kinetic-diffusive model (published by the authors in previous works) is used to describe the pozzolanic reaction. The kinetic parameters that characterize the process (in particular, the reaction rate constant and free energy of activation) are determined with relative accuracy in the fitting process of the model. The pozzolanic activity is quantitatively evaluated according to the results obtained for the kinetic parameters. This allows the comparison in a direct way of the pozzolanic reactivity of the materials, which is very useful for the employment of these materials for envisaged applications. The values of the reaction rate constant jointly with the free energy of activation give a precise index of the reactivity or pozzolanic activity of the materials. Complementary experimental techniques, such as X-ray diffraction (XRD) and scanning electron microscope (SEM), were also employed, but not shown in the paper for space reason since that would necessitate a much larger paper.
Materials
Supplementary cementitious materials (SCM) can reduce the total amount of Portland cement clinker in concrete production. Rice husk ashes (RHA) can be converted from an agricultural by-product to a high-performance concrete constituent due to a high amount of reactive silica with pozzolanic properties if they are burnt under controlled conditions. The way and duration of combustion, the cooling process as well as the temperature have an effect on the silica form and thus, the chemical and physical performance of the RHA. Various studies on the best combustion technique have been published to investigate the ideal combustion techniques. Yet, the process mostly took place under laboratory conditions. Investigating the difference between the performance of RHA produced in a rural environment and laboratory conditions is useful for the assessment and future enhancement of RHA production, and its application both as building material, for example in rural areas where it is sourced in lar...
An investigation of the effectiveness of the utilization of biomass ashes as pozzolanic materials
Construction and Building Materials
h i g h l i g h t s Evaluation of biomass ashes as SCMs, for concrete strength and chloride penetration. High SiO 2 content of biomass ash does not imply a pozzolanic material with a high efficiency factor. Concentration of other compounds, even for high SiO 2 content is responsible for low k-values. Biomass ash from agro-industrial by-products can be used as pozzolanic material in concrete.
Use of Rice Straw Ash as Pozzolanic Material in Cement Mortar
International Journal of Engineering and Technology, 2013
In this paper an experimental study was made on the effects of using Rice Straw Ash (RSA) as a partial replacement of cement in mortar. Control specimens with ordinary Portland cement (OPC) was made and in other specimens cement were replaced with 5%, 10% and 15% of RSA by weight of cement. Locally available rice straw was burnt to ash in uncontrolled manner in the earthen oven used by the rural people for cooking purpose, which were used in this study. The setting times and compressive strength of that mortar mix using RSA at different percentage of cement replacement was investigated and compared with the control specimen. The tests results obtained shows that setting times are delayed with increased amount of cement replacement and there is enhancement of strength of mortar with certain quantity of replacement of cement with RSA which will lead to reduction of construction cost.
Partial Replacement of Cement with Rice Husk Ash and its Pozzolanic Activity: A review
Rice husk ash (RHA) is a supplementary cementitious material (SCM) and precise study has been done so as to be incorporated in cement concrete as a partial replacement of cement. This paper reviews the insertion of Rice husk ash (RHA) in ordinary Portland cement in cement concrete by some certain amount and its pozzolanic activity due to which innovation and advancement can be seen in physical, mechanical, and structural properties of the concrete. Rice husk ash gives two effects in the mortar or cement concrete i.e., filler effect and pozzolanic effect. This study reviews the pozzolanic contribution of RHA towards cementitious system. The percentage replacement of the rice husk concrete used in the earlier studies were taken as arbitrarily like 5%, 10%, 20% so on to observe and calculate the total effect of the rice husk ash. Previous studies gave clear cut result about the better performance of rice husk ash concrete than conventional concrete. The hydration reaction which occurs due to cement and the additional pozzolanic reaction of RHA with the hydrated products generated earlier innovates and advances the various properties of rice husk ash concrete.
Study on Pozzolana Activity of Wheat Straw Ash as Potential Admixture for Blended Cements
Ceramics - Silikaty, 2017
Wheat straw ash coming from combustion of packed wheat straw was studied as a potential pozzolana active admixture for blended cements. X-Ray fluorescence, X-Ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy were used to examine chemical and mineralogical composition, morphology and elemental distribution of a raw untreated ash. Due to high carbon content, the wheat straw ash was thermally treated for 2 hours at 700°C and analyzed again using the same analytic techniques. Thermal treatment process was monitored using simultaneous thermal analysis and Fourier Transform infrared spectroscopy. The pozzolana activity was assessed using Chapelle and Frattini tests. In the next step, wheat straw ash was used for preparation of blended cement pastes. The content of ash in the blends was 10, 15, and 20 % by mass. For the hardened pastes, basic physical properties, mechanical parameters, and pore size distribution were measured. For fresh past mixes, workability was tested. Moreover, leachability of chlorides, nitrates, sulfates and alkalis from paste samples was studied. The experimentally obtained data pointed to the high pozzolana activity of wheat straw ash and sufficient mechanical properties of cement pastes with the ash content up to 20 mass % of cement. In summary, the analyzed waste product from biomass combustion was found to be applicable as a part of cement-based blended binder providing economic and environmental benefits for concrete industry.
Utilization of Sugar Mill Waste Ash as Pozzolanic Material in Structural Mortar
Minerals
Bagasse is produced as a waste in the sugar production process, which is used as fuel to stoke boilers in the sugar mills. The concluding product of this burning is residual sugarcane bagasse ash (BA), which is normally dumped or used as low-quality fertilizer. The ash for this study was collected from a reputed sugar mill located in the northern region of Bangladesh. Type I Portland cement (PC) was partially replaced with that finely ground bagasse ash without any pretreatment. The ground BA was used as a replacement for Portland cement at 5, 10, 15, 20, 25 and 30% of BA, respectively, in structural mortar. In addition, chemical characterization, specific gravity, X-ray diffraction (XRD), scanning electron microscopy (SEM), setting time, a strength activity index, compressive strength, water absorption, density and durability in a chloride environment of mortar were determined. The strength activity index result indicates that the used BA has the pozzolanic properties to be used as...
Development of Local Bagasse Ash as Pozzolanic Material for Use in Concrete
Pakistan Journal of Engineering and Applied Sciences, 2016
Concrete is one of the extensively used materials in construction industry. General construction uses ordinary Portland cement, however for specialized projects specific properties of concrete are tailored using different pozzolans. Sugarcane bagasse ash is abundantly available in Pakistan as being obtained from sugar mills which uses sugarcane bagasse as fuel. This research is focused to determine the maximum pozzolanic activity of sugarcane bagasse ash. Raw bagasse ash was calcined at temperatures of 500, 600 and 700 degree Celsius for 1, 2 and 3 hours heating duration. ASTM C 618 and C 311 were used to determine the suitability of sugarcane bagasse ash for its pozzolanic activity. It was found that maximum pozzolanic activity is achieved at a temperature of 500 degree Celsius for 1 hour heating duration and same was verified by X-ray diffraction analysis of calcined sugarcane bagasse ash
Pozzolanic Characteristics of Municipal Solid Waste Ash
Journal of Agricultural Science and Technology, 2013
Earth as a building material has been used over the years in the construction industry. However its strength characteristics have been inadequate. Therefore, stabilizers are used to enhance its strength. Where conventional stabilizing agents like cement and lime have been used, they have considerably increased the cost of construction. It is with this backdrop that this paper describes the pozzolanic characteristics of municipal solid waste ash (MSWA) and its use as a stabilizing agent. The total elemental concentration in the MSWA was determined by use of Total X-ray Florescence method, while the laser particle analysis method was used to determine the particle size distribution of the ash. X-ray Diffractometer method was used to measure the level of molecular compounds including the oxides of silicon, aluminium and iron. The Total X-Ray Florescence (TXRF) analysis indicated that the ash contained high levels of calcium (220,240 mg/kg) and mercury (23.76 mg/kg). According to the Canadian Public Health guidelines, this concentration of mercury exceeded the acceptable limit of 23 mg/kg. Calcite was the main oxide (57.6%) with its glass halos occurring between 20° to 50° two-theta. The total amounts of SiO2, Al2O3, and Fe2O3 were less than 70%, categorising the ash as Class F pozzolana meaning that MSWA was not self-cementing. Laser diffraction particle size analysis showed that the ash was mainly composed of particles finer than 0.002 mm (55.82%), with its probability distribution function depicting a bimodal curve. The municipal solid waste (MSW) had a high loss of ignition (83.49%), an indication that it contained high amounts of un-burnt carbon. Despite the low quartz (SiO2) content as compared to that of pozzolana cement, MSWA had high calcite (CaCO3) content enabling it to contribute to bonding effect of the ash. From the study, it is recommended that MSWA has to be used as a bonding agent and not as a cementing ash. Also the ash has to be finely ground prior to use as a pozzolanic material in soil stabilization, so as to increase both its filler and bonding effect.