rice husk ash

Rice husk as an agricultural waste material has a large amount of amorphous silica, adding its ash to concrete increases the pozzolanic property of concrete and consequently increases the strength and durability of reinforced concrete structures. The quality and method of rice husk ash preparation greatly influence the final properties of the concrete prepared from it. In this article, rice husk ash has been burned in controlled, semi-controlled, and uncontrolled conditions in terms of temperature conditions, and the resulting ash has been used as a 10% substitute for cement in self-compacting concrete. Properties related to concrete performance and compressive strength of samples containing rice husk ash at different ages have been evaluated. The properties of rice husk ash powder have been determined through XRF, FESEM, and the determination of grain size range. The results show that in all cases the sum of SiO2, Al2O3 and Fe2O3 is higher than 70%; which indicates being within the standard range of pozzolanic cement materials. In the semi-controlled state, the amorphous silica is more than 8%. Based on the results, adding rice husk ash increases the long-term compressive strength (90 days) and decreases the short-term compressive strength of self-compacting concrete. The increase in long-term strength for samples with ash produced in controlled conditions was more and up to 18%. The reduction of short-term compressive strength for samples with uncontrolled ash has been obtained up to 25%.

Sustainable materials in the field of road paving have become a research direction in recent years. In this study, rice husk ash with a small percentage of styrene-butadiene-styrene-1 (SBS) was added to base asphalt as a bio-additive to improve its properties. Different percentages (0, 2, 5, 10 and 15%) of rice husk ash 2 (RHA) and 1% SBS were selected to prepare modified bitumen. Penetration, softening point, ductility, rotational viscosity test and temperature sweep test were performed to investigate the properties of modified with SBS/RHA. To evaluate the performance of asphalt mixture modified with SBS/RHA, rutting, moisture sensitivity and low temperature cracking tests were used. The results showed that the penetration decreased and the softening point and rotational viscosity increased while the ductility decreased slightly with the incorporation of rice husk ash. The SBS/RHA modified asphalt mixture had better high temperature performance than the control asphalt mixture, but slightly lower moisture stability and lower temperature performance. The tensile strength ratio of the control and modified asphalt mixture meets the specification requirements. The tensile strain of the SR15 mixture was lower than the specification asphalt mixture requirement. For bitumen modified with SBS/RHA based on comprehensive properties, the percentage of rice husk ash should not be more than 15%.

Heavy metal contaminants are the most important and most hazardous type of pollution that needs to be studied both environmentally and geotechnically. There are different concentrations of heavy metals in the soils (Zhang et al, 2019). Engineering properties of contaminated soil tend to significantly change due to chemical reactions between the soil mineral particles and the contaminants (Arasan and Yetimoglu 2008). Chu et al. estimated the shear strength parameters of contaminated soil by lead, zinc and cadmium. The direct shear experiment was performed and results indicated that increase of heavy metal concentration increases shear strength and cohesion. Also, the electrical resistivity of soils decreased with the increase in concentration (Chu et al, 2016). Based on the spreading of the heavy metals such as Lead and Zinc in the most parts of China, Li et at. conducted research on lead contaminated soil in these areas. Samples were made in OMC and MDD and cured for 2 days. Obtained results showed that the increase of the concentration decreased the thickness of diffuse double layer (DDL) and particles were in a flocculated micro structure form. Increasing the flocculation, increased the permeability coefficient of samples (Li et al., 2015). In this study, the effects of zeolites and rice husk ash were investigated. It should be noted that the soil mixture was sand with 20% kaolinite and also sand with 20% bentonite. After determining the performance of these two types of clay minerals in contaminated and uncontaminated conditions, 10% of the fine-grained fraction were reduced and the equivalent of 10% of zeolite or rice husk adsorbents were added.

In this research, the mechanical properties of concrete in the conditions of using natural aggregates and comparing the results with the replacement of recycled aggregates with values of 10, 20, 30 and 40% have been investigated. In the first part of the study, the results showed that the specific gravity of concrete in the presence of 40% of recycled sand and gravel was 1.02% and 2.38%, respectively. Also, in terms of compressive strength, the lowest decrease in compressive strength occurred in 10% of recycled sand and the highest decrease in compressive strength occurred in 40% of recycled sand. Then, the mechanical properties of ordinary concrete with concrete containing waste plastic (PET) were compared with 2, 4, 6, 8 and 10% of concrete volume. In this regard, the results of the study indicate a decrease in compressive strength of concrete compared to control concrete. In this regard, the lowest reduction in compressive strength was 2.01% in the presence of 2% waste plastic (PET) and the highest reduction in compressive strength was 16.39% in the presence of 10% waste plastic (PET). Regarding flexural strength, the results showed an increase in flexural strength; So that the lowest increase in flexural strength of 6.27% occurred in the presence of 2% waste plastic (PET) and the highest increase in flexural strength of 39.49% occurred in the presence of 10% waste plastic (PET). In the end, the results showed that increasing the presence of waste plastic (PET) has led to a decrease in water absorption of samples. In this regard, the lowest decrease in water absorption by 5.26% and the highest decrease in water absorption by 23.08% occurred in the presence of 2 and 10% waste plastic (PET), respectively.

Ever-growing concern to protect the environment concentrated the attention of the society on the possible re-use of different agricultural and industrial wastes in road construction. This research study depicts the effect of using wastes like rice husk ash (RHA) and fly ash (FA) as a replacement of conventionally used hydrated lime (HL) as fillers in hot-mix asphalt (HMA). Primarily, the dense graded bituminous macadam (DBM) mix specimens were made in the laboratory with varying proportions ranging from 2% to 8% of HL, RHA and FA by following design mixes according to the Marshall method and compared the results with control mix as prepared by utilizing 2% HL. The performances of the said mixes were studied through the Marshall Quotient, indirect tensile strength and tensile strength ratio. Results of investigation show better performance of HMA with the addition of RHA and FA and also proved to be economical as the optimum bitumen content is reduced by 7.5% from that of control mix when added at 4% filler ratio. Further, RHA shows a greater affinity to the bitumen attributing the highest stiffening effect of the bituminous mastic droplets compared to that of other used fillers with good compatibility at the micro level by satisfying the essential criterion.

In this paper, using rice husk ash (RHA) in hot mix asphalt (HMA) as filler was evaluated. The main aim of replacing mineral filler is enhancing the performance of asphalt mixes and producing an economical asphalt mix. For this purpose, five different mixes were prepared; the first was a control mix (traditional mix) containing 100% Lime Stone Dust (LSD) as filler and 0% RHA. While, the other mixes contain 25%, 50%, 75% and 100% of RHA as a percentage of the filler weight. Optimum bitumen content (OBC) was determined using Marshall test, also all Marshall parameters (Stability, Air Voids, Voids in Mineral Aggregate, Unit Weight and Flow) were examined. Indirect Tensile Strength Test (ITST) and Wheel Tracking Test (WTT) were conducted and their results were analyzed. Dynamic modulus (│E*│) is considered an important parameter used in mechanistic-empirical pavement design. The │E*|is measured at different temperature/frequency combinations. Dynamic modulus (│E*│) and phase angle (δ) are used for the visco- elastic characterization of HMA. Thus, these properties were measured for mixes with and without RHA. The results indicate that RHA has the potential to be used as partial substitution of mineral filler LSD in pavement construction. Adding RHA enhances Marshall stiffness, reduces rut depth and increases indirect tensile strength values. Further, a significant change has been occurred in OBC for all mixes and the optimum replacement ratio is recorded as 50% RHA: 50% LSD. Finally, mixes containing RHA show higher dynamic modulus values and flow number.

This paper aims to investigate and compare the properties of highly plastic clay soil stabilized by geopolymers synthesized from various industrial residues and rice husk ash. To this end, steel slag, fly-ash and diatomite were used as the base material, and NaOH solutions of 8.68 M and Na2SiO3 solutions extracted from rice husk ash were used as an alkaline activator for stabilization. Stabilization was performed using 10, 20 and 30 percent of base materials by dry weight of soil. Samples were compacted at optimum moisture content and were cured for 7, 28 and 90 days. The results of the experiments show that the application of geopolymer as a stabilizer improve the compressive and tensile strength, increase Young's modulus and reduce the failure strain of the stabilized clay soil. The highest increase in the unconfined compressive strength (UCS) was related to stabilized clay with geopolymer synthesized using 30% of steel slag, its UCS was 25.2 times higher than the untreated clay soil. Also, the samples stabilized with geopolymer synthesized using 30% of fly-ash and 30% of diatomite showed the UCS of 4.05 and 12.72 times more than the untreated clay soil, respectively. The results of this study also showed that the stabilization of clay using geopolymer significantly increases the indirect tensile strength (ITS) of the samples, so that the samples stabilized with geopolymers based on the 30% of steel slag, 30% of fly-ash and 30% of diatomite, had an ITS of  23.14, 7.58 and 12.5 times more than untreated clay soil, respectively.

Portland cement is one of the most common materials for improving the mechanical properties of soils; however, it has a lot of detrimental effects on the environment. Cement production releases million tons of carbon dioxide gas (CO2) to the air and uses million tons of raw material such as clay and limestone. For this purpose, geotechnical engineers are looking forward to using a new friendly environment material instead of cement. Geopolymers are new alternative materials that have some advantage such as high resistance, friendly environment, long durability, and low cost. Two materials need to make a geopolymer matrix. First, any materials have silicate and Aluminium oxide and Second Alkaline activators. In this study, a geopolymer based on rice husk ash and iron ore tailings (IOT) are used for sandy soil stabilization. Two types of alkaline activators are used: 1) Type I sodium hydroxide and 2) Type II carbide calcium residue. Various parameters such as type of material consumed, percentage of compound composition, type of alkaline activator, and processing time are considered as influencing factors in the behavior of the stabilized specimens. Unconfined Compressive Strength (UCS) and splitting tensile strength tests (Brazilian test) are the main criteria for a comparison of the specimens to evaluate the effect of a geopolymer on the mechanical behavior of the specimens. X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) analyses are performed to investigate the microstructures of the stabilized soil. The results show that by adding the optimum amount of additives and handling the specimens under ambient conditions, the unconfined compressive strength of the specimens increased. The optimum percentage of selected specimens is a combination of 10% of rice husk ash and 24% of iron ore tailings for activator I and 18% of iron ore tailings for activator II. The use of type I activator indicates that it is highly effective in the formation of aluminosilicate gels in geopolymer compounds.

The purpose of this paper is to investigate the effect of coal waste ash and rice husk ash on mechanical properties of the stone matrix asphalt mixtures. In this study, of coal waste ash and rice husk ashes was used as a substitute for limestone powder in percentages (0 %, 25 %, 75 %, 75 % and 100 %)in the stone matrix asphalt mixtures. also to prevent drain down of this mixture, the cellulose fibers and SBS polymer fibers were used. in order to investigate the performance characteristics of mixtures the Marshall stability test,  Resilient modulus, indirect tensile strength, moisture  sensitivity, dynamic creep, and wheel tracking tests were performed. the results showed that the replacement of rice husk ash with limestone powder has improved the performance characteristics of the mixture. While the use of coal waste ash is only enhanced the moisture sensitivity of mixtures and it has a negative effect on the performance properties of mixtures.

The purpose of this paper is to investigate the effect of coal waste ash and rice husk ash on mechanical properties of the stone matrix asphalt mixtures. In this study, of coal waste ash and rice husk ashes was used as a substitute for limestone powder in percentages (0 %, 25 %, 75 %, 75 % and 100 %)in the stone matrix asphalt mixtures. also to prevent drain down of this mixture, the cellulose fibers and SBS polymer fibers were used. in order to investigate the performance characteristics of mixtures the Marshall stability test,  Resilient modulus, indirect tensile strength, moisture  sensitivity, dynamic creep, and wheel tracking tests were performed. the results showed that the replacement of rice husk ash with limestone powder has improved the performance characteristics of the mixture. While the use of coal waste ash is only enhanced the moisture sensitivity of mixtures and it has a negative effect on the performance properties of mixtures.

Nowadays, cement is broadly applied to stabilize the soil to improve the mechanical and engineering properties of different soils and to control their deformations and swelling behavior. Nevertheless, due to the high expenses, civil engineers have always been trying to find an economic pozzolanic alternative for cement. In this regard, lots of construction materials such as fly ash, lime, blast furnace ash, pond ash, rice husk ash, etc are added to differentsoil materials to find an optimum replacement for the cement. Among the mentioned materials, rice husk ash (RHA), which is widely available in Guilan, Iran, is an environmentally dangerous material (if dumped in the nature). Hence, application of this material will be both economically and environmentally useful. Also, due to its high applicability, it can be easily applied in civil constructions. Hence, application of RHA in civil/construction projects will be considerably useful. On the other hand, different fibers (e.g. plastic, polyester, polypropylene, etc) are used for engineering purposes to both control the process of crack initiation and increase the material mechanical properties. the length of applied fibers, also, their percentage is two famous controlling parameters of applying fibers in soil stabilization programs. In this paper, a new soil stabilization method is introduced to stabilize Anzali sand using the combination of cement and RHA. Also, the possibility of cement replacement with RHA is investigated. Polypropylene fibers in 0.2 and 0.4 percentages are also added to the samples to control the growth of tensile cracks and to evaluate their effect on the compressive strength of stabilized samples. Hence, cement in 3, 5, 7.5, 10 percentages, also, RHA in 3, 5, 7.5, 10, 12 and 15 percentages are added to the sand samples to increase their compressive strength. Samples are cured for 28 days and unconfined compressive strength tests are conducted on the stabilized and reinforced samples. Based on the test results, compressive strength of all the samples were increase as cement and RHA percentages were increased. Also, RHA is introduced as a capable replacement additive for the cement. In order to make a generalization and provide a relationship for practitioners to use the results of the present study, different techniques can be adopted. Among them, artificial intelligence techniques are most in demanding ones. Neural networks, gen programming languages, genetic algorithms and evolutionary approaches can be applied to provide such relationships. In this paper, evolutionary approaches are considered and using evolutionary polynomial regression technique, simple predictive equation for forecasting UCS is proposed. In this regard, based on the results of conducted un-confined compressive strength tests, Evolutionary Polynomial Regression (EPR) technique is applied and a high accuracy predictive relationship for forecasting UCS of cement-RHA stabilized and polypropylene reinforced sand is presented (coefficient of determination of 94.4%). In addition, sensitivity analysis based on Cosine Amplitude Method (CAM) is carried out to investigate the most and the least effective materials on the compressive strength of samples. CAM analysis showed that although cement and RHA have meaningful effect on the determination of UCS, polypropylene percentage is the most sensitive additive controlling the variation of UCS.

Sulfate attack is a series of physico-chemical reactions between hardened cement paste and sulfate ions. Sulfate ion penetration into the cement results in the formation of voluminous and deleterious phases such as gypsum and ettringite which are believed to cause deterioration and expansion of concrete; However, there is no direct relationship between Ettringite or solids formation during the sulfate attack and the amount of expansion. Concrete deterioration due to sulfate attack depends on multiple elements, however, in experimental studies, the implementation of the elements and obtaining the results in a short time are very difficult. Therefore, the significance of theoretical and software modelling along with in experimental studies, reducing the time and cost, increases so much as to achieve reliable results. Thermodynamic simulations, in this research, are employed according to the method of minimizing Gibbs free energy in order to better understand the external sulfate attack and the behaviour of mortar samples made of ordinary Portland cement and blended cements.GEM software helps in studying the microstructure of cement, volume and type of phases formed in sulfate solutions under different conditions. With this software, a virtual laboratory of materials could be created, which simulates natural processes such as hydration, sulfate attack, and factors that affect them with less time and cost. This modeling type could be utilized for cement systems in order to calculate sets of stable phases. A system achieves thermodynamic equilibrium when there is no more spontaneous tendency for change. GEM software which is able to calculate the stable phase as a function of reactants, temperature and pressure is employed. In this software chemical interactions involving solids, solid solutions, metls, gas/fluid mixture, aqueous electrolyte, (non-)electrostatic surface complexation, and ion exchange can be considered simultaneously in the chemical elemental stoichiometry ( electrical charge) of the system, i.e. without any mass balance constraints for ligands or surface sites. GEMS simulates various mass-transfer processes and reaction paths, such as mixing; But this software cannot replace our knowledge of physical chemistry. Type and volume of phases formed during the sulfate attack and factors affecting that such as cement chemistry, rice husk ash and sulfate solution with different concentrations were studied With the help of this method. Simulation of mortar samples was performed in sodium sulfate with concentrations of 4 and 44 g per liter and 10 and 15 percent rice husk ash substitution. Mortar samples at 20 ° C and water-cement ratio of 0.5 is assumed. Rice husk ash substitution has an effective role in microstructures improvement, reduced impermeability, and volume of forming products. Sodium sulfate is more dangerous and destructive compared to other sulfates like calcium sulfate or potassium sulfate and forms phases with higher volumes. The results clearly indicate that rice husk ash, consumed portlandite completely and produced maximum volume of calcium silicate hydrate(C-S-H) by 15 percent replacement and also there is not a simple relationship between the increase of formed phases by the penetration of sulfate ions and the observed expansion. Generally, the results correspond to the studies and in experimental results which have examined micro structure.

self-compacted concrete(SCC) is a concrete that can flow in the space between reinforcement without separation and compact only by their own weight. In this study, the effect of using silica fume, metakaolin, rice husk ash and fly ash with different ratios of 10% and 20% by weight of cement in self-compacting concrete containing magnetic water is concered. The fresh properties of self compacted concrete were's tested by means of slump flow, T50, V-funnel, L-box and visual stability index(VSI). The hardened properties were assessed, using compressive strength at the ages of 7 and 28 days. Also splitting tensile strength and water absorption test were assessed at the age of 28 days. In addition, concrete specimens were made using tap water and magnetic water, was passed through a magnetic field of 0.8 Tesla. The results show that pozzolanic materials are suitable in properties of self-compacting concrete containing magnetic water in terms of flowability and viscosity. Moreover, magnetic water can reduce the amount of superplasticizer, required for SCC, up to 45%. Also the results of hardened SSC show an improvement in mechanical and durability properties of concrete. The usage of silica fume with ratio 20% by weight of cement in self-compacting concrete containing magnetic water, increases the compressive and splitting tensile strengths by 48% and 35% respectively and decreases amount of water absorption by 55% at the age of 28 days.

Nowadays, by increasing of the load and volume of traffic passing through asphalt pavements, increase in the durability and resistance of these types of mixtures have become more of interest to researchers. Using appropriate filler is of the factors affecting the quality of asphalt production. Although low amounts of fillers are used for preparing asphalt mixtures, their significant influence has become specified and wide researches have been performed on this subject. As the fine part, filler has an effective role on the mechanical and behavioral properties of asphalt mixture and influences the interlock of materials, intensively. Some results indicate that most of biomass ashes are of various elements that are useful for asphalt. Rice husk ash, which is considered as a biomass ash, is one of the waste products obtained from furnaces at power plants, which is obtained due to the burning of rice husk. Currently, rice husk ash is widely used due to its beneficial properties in the concrete production industry. In this research, rice husk ash was used as a replacement for a part of filler (rock powder) in hot mix asphalt. First, Marshall Samples were prepared to determine the optimum bitumen content based on grading No. 4 and 5 in the percentages of 0, 25, 50, 75 and 100 of rice husk ash, as the replacement of the rock powder. Then, new samples with optimum bitumen content were obtained and prepared according to the previous gradation. Finally, the effect of using rice husk ash on rutting phenomena, moisture sensitivity and resilient modulus of hot mix asphalt was investigated. The results showed that using this additive by an optimum extent improves the asphalt performance, significantly.

Utilization of pozzolanic materials is one of the strategies applied to reduce pollution emitted during cement production. In this regard, rice husk ash produced through controlled incineration shows high pozzolanic performance which causes reasonable improvement in mechanical and durability properties of concrete materials. Moreover, acid treatment before incineration process is one of the most effective methods which is attracted less attention.
According to the above mentioned issues, in the current study, the influence of acid treated rice husk ash on mechanical and durability characteristics of concrete was investigated. In addition, to make an exact comparison, concrete mixtures incorporating untreated rice husk ash, zeolite, and silica fume were fabricated and tested. Testing program includes compressive strength, water penetration under pressure, electrical resistivity, half-cell potential, and rapid chloride permeability tests.
Results indicated that acid treated rice husk ash performed much better than untreated one and zeolite in increasing compressive strength and durability indices. Moreover, concrete containing silica fume had higher durability compared to concrete incorporating treated rice husk ash; however, the influence of treated rice husk ash on compressive strength was very similar to silica fume.