Effect Of Rice Husk Ash Research Articles

Mechanical properties and durability assessment of rice husk ash concrete

The effect of rice husk ash (RHA) on concrete properties and durability was studied. To establish the suitable proportion of RHA for the partial replacement of cement, concrete mixtures with 0–30% RHA were produced and their mechanical properties were determined. The effect of RHA on the uniformity of concrete was also examined. The durability of the specimens exposed to aggressive environments (5% NaCl with wet-dry cycling) was evaluated for a total of eleven months. The degree of damage was studied by determining the percentage of reduction in compressive strength and chloride ions penetration as compared with control specimens that had cured normally. The results indicate that the partial replacement of cement by RHA improved durability and homogeneity but did not increase the early age compressive strength of concrete. However, concrete containing RHA showed higher compressive strength at the later ages. The scanning electron microscopy (SEM) studies of the microstructure of mortar specimens showed that the RHA filled up the pores and this explained the superior mechanical performance of the mortar with RHA.

Effect of rice husk ash (RHA) on the properties of Ibaji burnt clay bricks

Effect of rice husk ash (RHA) on the properties of Ibaji burnt clay bricks

Effect of rice husk ash on the strength and durability characteristics of concrete

This work investigates the effects of adding residual rice husk ash (RHA) from South Vietnam, generated when burning rice husk pellets in the boiler, to cement. To improve pozzolanic reactivity, RHA was ground for 1 h. The non-ground RHA and ground RHA were used to test strength activity index according to ASTM C311. The properties of the concrete were investigated, including compressive strength, concrete electrical resistivity, and ultrasonic pulse velocity. Results show that the non-ground RHA can be applied as a pozzolanic material. Decreasing the non-ground RHA average particle size provides a positive effect on the compressive strength of mortar. Compressive strength of cylindrical concrete in the 47–66 MPa range was obtained in this study. The results also indicate that up to 20% of ground RHA could be advantageously blended with cement without adversely affecting the strength and durability properties of concrete.

The study of using rice husk ash to produce ultra high performance concrete

The limited available resource and the high cost of silica fume (SF) in producing ultra high performance concrete (UHPC) give the motivation for searching for the substitution by other materials with similar functions, especially in developing countries. Rice husk ash (RHA), an agricultural waste, is classified as “a highly active pozzolan” because it possesses a very high amount of amorphous SiO 2 and a large surface area. The possibility of using RHA to produce UHPC was investigated in this study. The result shows that the compressive strength of UHPC incorporating RHA, with the mean size between 3.6 μm and 9 μm, can be achieved in excess of 150 MPa with normal curing regime. The interesting point is that the effect of RHA on the development of compressive strength of UHPC is larger than that of SF. Besides, the sample incorporating the ternary blend of cement with 10% RHA and 10% SF showed better compressive strength than that of the control sample without RHA or SF. This blend proved to be the optimum combination for achieving maximum synergic effect.

Long Term Effect of Rice Husk Ash on Strength of Mortar

Long Term Effect of Rice Husk Ash on Strength of Mortar

Flowing ability of the mortars formulated from self-compacting concretes incorporating rice husk ash

This paper presents the flowing ability of the mortars formulated from various self-compacting concretes (SCCs) incorporating rice husk ash (RHA). The mortars were produced with different RHA contents and water–binder (W/B) ratios, as used in their parent SCCs. The flowing ability of the mortars was determined with respect to the flow spread at various dosages of a polycarboxylate based high-range water reducer (HRWR). The effects of RHA, W/B ratio, and HRWR on the flowing ability of mortars were observed. The mortar flowing ability decreased with the higher RHA content and W/B ratio, but increased with the greater HRWR dosage. However, the excessive HRWR dosages were not conducive to the mortar flowing ability due to the segregation problem in the form of bleeding. The overall mortar flowing ability results were useful to examine the suitability of RHA, and to fix the HRWR dosages for different SCCs.

Effect of rice-husk ash on durability of cementitious materials

Abstract In this paper the effects of partial replacements of Portland cement by rice-husk ash (RHA) on the durability of conventional and high performance cementitious materials are investigated. Different percentages of RHA replacement levels, two RHAs (amorphous and partially crystalline optimized by dry-milling) and several water–cementitious materials ratio are studied. The following durability aspects were tested: air permeability, chloride ion penetration, alkali-silica expansion, sulfate and acid resistance. The results were compared with those of cementitious materials without RHA. It is concluded from the tested properties that the incorporation of both RHAs in concretes show different behaviors for air permeability and chloride ion penetration depending on the water/cementitious materials ratio used; in mortars, it reduces the mass loss of specimens exposed to hydrochloric acid solution and decreases the expansion due to sulfate attack and the alkali-silica reaction. The results of durability aspects due to physical or pozzolanic effects after the addition of both RHAs, and its chemical composition, in general indicate an enhanced performance, proving the feasibility of its rational utilization as a supplementary cementing material.

Hardened properties of self-consolidating high performance concrete including rice husk ash

This paper mainly presents the key hardened properties of self-consolidating high performance concrete (SCHPC). Various SCHPCs were produced with different water/binder (W/B) ratios, rice husk ash (RHA) contents, and air contents. The required filling ability and air content were achieved in all freshly mixed SCHPCs. The hardened SCHPCs were tested for compressive strength, ultrasonic pulse velocity, water absorption, total porosity, and true electrical resistivity. The effects of W/B ratio, RHA content, and air content on these hardened properties were observed. Test results revealed that the compressive strength, ultrasonic pulse velocity, and electrical resistivity increased whereas the water absorption and total porosity decreased with lower W/B ratio and higher RHA content. In addition, the air content decreased the compressive strength, ultrasonic pulse velocity, water absorption, and total porosity but increased the electrical resistivity. Based on the overall effects of rice husk ash, the optimum RHA content for SCHPC has been defined.

Studies on the Effect of Rice Husk Ash as Cement Admixture

Compressive strength tests were carried out on six mortar cubes with cement replaced by rice husk ash (RHA) at five levels (0, 10, 20, 30, 40 and 50%). After the curing age of 3, 7, 14 and 28 days. The compressive strengths of the cubes at 10% replacement were 12.60, 14.20, 22.10, 28.50 and 36.30 N/mm2 respectively and increased with age of curing but decreased with increase in RHA content for all mixes. The chemical analysis of the rice husk ash revealed high amount of silica (68.12%), alumina (1.01%) and oxides such as calcium oxide (1.01%) and iron oxide (0.78%) responsible for strength, soundness and setting of the concrete. It also contained high amount of magnesia (1.31%) which is responsible for the unsoundness. This result, therefore, indicated that RHA can be used as cement substitute at 10% and 20% replacement and 14 and 28 day curing age.

Effect of rice-husk ash on exchange acidity, growth and yield of groundnut (<i>Arachis hypogaea</i> l.) in an acid ultisol.

Response of groundnut grown on acidic soil to rice-husk ash applied at 0, 1, 2, 3 and 4 t ha-1 was studied in two field experiments in 2005 and 2006 at Ishiagu in the derived savanna zone of southeast Nigeria. Treatments were fitted in a randomized complete block design (RCBD) replicated three times. Effects of treatments on some soil fertility and productivity parameters were evaluated. The rice-husk ash used contain 64.00 g kg-1Ca, 12.20 g kg-1 Mg, 12.50 g kg-1 P, 9.00 g kg-1 K, 2.10 g kg-1 N, 1.23 g kg-1 organic carbon and had a pH of 10.86. Soil pH increased from initial values of 5.16 to 6.20, while levels of exchangeable acidity correspondingly decreased from initial values of 0.80 to 0.26 cmol kg-1 with 3 t ha-1 applied rice-husk ash. Estimation of linear and quadratic curves respectively for soil pH and exchange acidity show values of r2 = 0.95 for soil pH and R2 = 0.98 for exchange acidity. Significant increases (P < 0.01) in soil P, K and Ca status relate significantly (P = 0.05) to patterns of growth and kernel yield of the crop. The 3 t ha-1 rice-husk ash is recommended. No significant yield advantage was observed at 4 t ha-1.

Investigation on the Hydration Properties of the Rice Husk Ash Cement Using Ftir and Sem

Effect of Rice husk ash on hydration properties of rice husk ash cement paste are reported in this paper. Rice Husk Ash (RHA) is used to replace 20% of Portland cement and water to solid ratio is 0.4. The hydration products observed due to rice husk ash addition were confirmed using the characteristic peak of Fourier Transform Infrared (FTIR) spectra and the micro structural changes were noted using Scanning Electron Microscope (SEM) micrographs. The rice husk ash cement paste gains more strength due to the production of more Calcium Silicate Hydrate (CSH) gel (pozzolanic reaction products).

Effects of RHA on autogenous shrinkage of Portland cement pastes

In this work, the effects of partial replacements of Portland cement by rice-husk ash (RHA) on the autogenous shrinkage were investigated. Pastes with water/binder ratio 0.30 and substitutions of 5% and 10% cement by RHA were tested. Two RHAs, both amorphous and partially crystalline, were studied. Comparisons between pastes with silica fume, and control pastes (without RHA or silica fume) are presented. Autogenous deformations, internal relative humidity and compressive strength were recorded. The RHA, amorphous or partially crystalline, when used in an appropriate way, reduces autogenous shrinkage.

Effect of rice husk ash (RHA) in the synthesis of (Pr,Zr)SiO 4 ceramic pigment

In this work the screening results of the scientific activity conducted on the possibility to use rice husk ash as silica precursor for ceramic pigments are reported. Ceramic pigments were synthesized by solid-state reactions and the color developed in a suitable ceramic glaze was investigated in comparison with the color developed by the pigments prepared from pure SiO 2.

Design and analysis of single-factor experiments: Analysis of variance of the effect of rice husk ash and commercial fillers in NR compounds

White rice husk ash (WRHA) and black rice husk ash (BRHA) were incorporated into natural rubber (NR) using a laboratory-sized two-roll mill. A conventional vulcanization system was used for curing and physical tests of the NR vulcanized involved determining of tensile and tear resistances. For comparison purposes, precipitated silica (Zeosil-175) and carbon black (N774) were used too. Using the analysis of variance of single-factor experiments, it can be concluded that: BRHA is non-reinforcing filler and its use is limited to 20 phr; WRHA is semi-reinforcing filler and the variation of filler loading (0 up to 50 phr) causes the maximum variation upon tensile strength of NR compounds; and, that although carbon black and silica are reinforcing fillers, a real reinforcement is reached up to 20 phr for tensile strength.

THE EFFECT OF STEEL FIBERS ON THE MECHANICAL PROPERTIES OF HIGH PERFORMANCE CONCRETE

The present investigation considers the effect of steel fibers content and the combined effect of rice husk ash (RHA) and high range water reducing agent (HRWRA) on the mechanical properties of the produced matrix. The experimental results showed the using steel fibers in High-performance concrete led to a considerable improvement in mechanical properties of concrete. The results exhibited that the addition of steel fibers to high performance concrete up to 1% with 6% (HRWRA) and 8% (RHA) as a partial replacement by weight of cement, increases the compressive strength significantly. Also, the results showed that the addition of 1.5% steel fibers with 6% (HRWRA) and 8% (RHA) increases the splitting and flexural strengths significant. At 28 days, the compressive, splitting and flexural strengths were increased to 11.57%, 63.86%, and 32.93% more than High performance concrete without steel fibers, respectively. Key words: Concrete, Mechanical properties, High performance concrete, Strength, Admixtures

Effect of Rice Husk Ash and Phosphorus on Some Properties of Acid Sands and Yield of Okra

Investigations were conducted to determine the effects of rice husk ash (RHA) and phosphorus (P) on soil pH, cation exchange capacity, base saturation, growth, and yield of okra [Abelmoschus esculentus (L) Moench]. The experiment was a 5×3×3 factorial in randomized complete block design. The soil used for the experiment was a Typic Paleudult within the “Acid Sand” soils of Calabar. Elemental analysis of RHA and fresh rice husk are also presented in this article. The results showed that organic carbon (OC) and total nitrogen (TN) were lower in the ash than in the fresh Rice Husk (RH) samples. The combination of 20 t RHA ha−1 and 40 kg P ha−1 gave the best yields of 4.80 t ha−1 fresh fruits compared to 2.69 t ha−1 in the control. Soil pH increased from 4.4 to 5.8 and from 4.9 to 6.0 in the pot and field experiments, respectively, at the optimum level (i.e., 20 t RHA ha−1, 40 kg P ha−1, and 50 kg N ha−1). The 50 kg N ha−1 was applied to all treatments to avoid N deficiency. The trends, however, followed a strong positive linear correlation. Increases in exchangeable magnesium (Mg), potassium (K), and effective cation exchange capacity (ECEC) were observed in the soil. A mean neutralizing value as low as 1.62% (calcium carbonate equivalent) and 19.35 g kg−1 OC, inherent in the RHA, was found to be responsible for ameliorating the soil acidity and thus, improving fertility of the acid sands. The RHA had no effect on the already adequate soil available P especially at high levels (RHA >20 t ha−1). In conclusion, because RHA could amend the soil acidity and keep the soil more fertile with increase in available nutrients and maintain optimum pH, it is recommended for trial as an invaluable, environmentally friendly, cheap and low‐input material for improvement of fertility of the “Acid Sands” of southeastern Nigeria.

Effect of Rice Husk Ash and Natural Zeolite on Reducing Expansion due to Alkali-Aggregate Reaction

Effect of Rice Husk Ash and Natural Zeolite on Reducing Expansion due to Alkali-Aggregate Reaction

Effect of rice husk ash in whiteware compositions

Quartz was progressively replaced by ground active silica obtained from rice husk ash (RHA) in a traditional whiteware composition and the effect of this replacement on the vitrification behaviour and mechanical and thermal properties in relation to the microstructure of specimens has been investigated. It has been found that the complete replacement of quartz by RHA drastically reduced both the maturing temperature and the percentage of thermal expansion, and increased the strength marginally. The improvement in the properties is attributed to sharp changes in the microstructural features as a result of significant reduction in the content of quartz phase and the simultaneous increase in glassy phase.

Low reoxidation tundish metallurgy at Fundia Koverhar steel plant

Production of Al killed steel grades at Koverhar began in 1992 after revamping the casting machine no. 1. The refractories and equipment of caster no. 1 were planned to prevent reoxidation. However, nozzle clogging problems with impaired inclusion cleanliness were occasionally observed. In order to clarify the rôle of reoxidation in continuous casting, a research project was carried out with the Helsinki University of Technology. The whole casting sequences of 3 steel grades were scrutinized. The changes of steel composition from ladle to mold as well as tundish slag composition were systematically investigated. The starts of casting sequences, ladle changes and cast endings were especially examined. The effects of rice husk ash as the tundish cover and the carryover of ladle slag to the tundish were studied as well. The research project clearly revealed different reoxidation phenomena during the casting process. Exchange reactions between the steel and the tundish slag caused reduction of silicon and manganese oxides from the slag to the steel and oxidation of aluminium, eventually titanium, from the steel, respectively. These reactions, however, did not impair steel cleanliness, as oxide inclusions produced by the reactions were formed in the vicinity of the metal‐slag interface, and thus inclusions were readily removed to the slag. Nitrogen pick‐up was observed especially during the cast starts, indicating atmospheric reoxidation. It had, however, neither any notable influence on steel cleanliness nor on castability. Any tendency to clogging was not observed during the campaigns.

The Effect of Rice Husk Ash as a Filler for Epoxidized Natural Rubber Compounds

The effect of rice husk ash (WRHA) as a filler in epoxidized natural rubber compounds has been studied. The mechanical properties viz tensile and tear strength were enhanced by the addition of WRHA. The optimum level of WRHA to obtain maximum mechanical properties was achieved at 20 phr after which there was deterioration in properties. Hardness and torque increased steadily with WRHA loading while scorch and cure time, t90 showed the opposite trend. The presence of silane coupling agent, γ-mercaptopropyl trimethoxy silane (A-189) has increased the effectiveness of WRHA as a filler for ENR compounds.