Influence of Rice Husk Ash on Crystalline Phases and Mechanical Characteristics of Sustainable Bricks

Use of supplementary construction materials in concrete industries has become a great interest in recent years. Stringent guidelines of the Unites States Environmental Protection Agency (EPA) influence the use of recycled materials in construction industry. Furthermore, there is an eminent shortage of the predominately used fly ashes from local sources generated by coal plant industries in Arkansas. On the other hand, rice husk ash (RHA), a by-product of the rice milling process, has high potential of being a supplementary cementing material. The RHA generated by Riceland Foods, the largest grain processing industry in the United States located in Arkansas, is treated as waste materials. It has become a financial burden to local famers due to its ever increasing handling, storage and disposal costs. The RHA consists of non-crystalline silica, which proves it as a very reactive pozzolanic material in mortar and concrete. To this end, laboratory-based experimental study investigated the performance of a locally available RHA as a supplement of Type-I Ordinary Portland Cement (OPC). Properties of concrete with different percentages of RHA (10% and 20% by weight) were investigated in this study. Fresh concrete properties (slump, unit weight, air entrainment etc.) as well as mechanical properties (compressive, tensile, flexural strength) of hardened concrete were determined. Additionally, alkali-silica reaction (ASR) test was conducted on mortar bars to evaluate cracking and expansion of concrete while exposed to adverse weather. It was found that, RHA particles were 13 times coarser than the cement particles. Use of this bulk RHA yielded significant strength reduction of the RHA modified concrete compared to the control sample. The maximum compressive strength gained by 10% RHA-modified concrete was 56% of that of the control specimen. Tensile and flexural strengths achieved by 10% replacement level were 76% and 96%, respectively, of those of the control samples. Moreover, the ASR test revealed that the bulk RHA was very reactive. Local construction industries can use this RHA as flowable fill as an alternative of cement and fly ash.

Self compacting concrete is a recently developed concept in which the ingredients of the concrete mix are proportioned in such a way that it can flow under its own weight to completely fill the formwork and passes through the congested reinforcement without segregation and self consolidate without any mechanical vibration. The basis of SCC is high content of ultra fines which consists of one or more varieties of mineral admixtures and chemical admixtures. An attempt has been made in the investigation reported in this paper to study the influence of rice husk ash on the fresh, hardened properties and stress-strain behaviour of standard grade (M 30) SCC. Three SCC mixes with optimized quantities of mineral admixtures like fly ash(FA), ground granulated blast furnace slag (GGBS) and combination were designed based on Nan-Su method of mix design and are taken for investigation. To these optimized mixes rice husk ash (RHA) was added in different proportions and tested in fresh and hardened states. Incorporation of small quantity of RHA has shown considerable reduction in flowability of SCC. Significant improvement in the compressive, tensile and flexural strengths is observed due to the addition of RHA to SCC mixes. It is observed from the Stress-Strain response that blending of RHA to SCC mixes have shown improved stress values for the same strain levels

This paper examines studies on the use of rice husk ash (RHA) and snail shell ash (SSA) as partial Ordinary Portland cement (OPC) replacements in concrete and their effects on concrete properties. RHA contains over 80% amorphous silica, along with other oxides in small quantities. Scanning electron microscopy (SEM) analysis showed that RHA has irregularly shaped particles with a porous, cellular structure. Similarly, chemical analysis of SSA revealed it contains over 60% active calcium oxide with minor oxides, and SEM analysis showed it has irregular semi-spherical particles with porous surfaces. The replacement of cement with RHA led to improved mechanical and durability properties in concrete, although workability was reduced. RHA also demonstrated resistance to chloride penetration. Combining RHA and SSA has the potential to produce stronger, more durable concrete, and could replace cement in high volumes in concrete production.

Conventional concrete significantly affects the environment due to high CO2 emission into the atmosphere during the production process. In order to improve concrete performance and arrest the incidence of global warming, the use of additive materials for cement replacement has been promoted worldwide. This study was designed to investigate the mechanical properties of high-performance fiber-reinforced concrete (HFRC) produced using rice husk ash (RHA) and hybrid fiber (HF) in accordance with the densified mixture design algorithm (DMDA) mix design method. Samples were produced using RHA as a direct replacement for cement at 10%, 20%, and 30%. HF, comprising steel and polypropylene fibers, was added (by volume) to the 20% RHA group mixture to improve the HFRC sample properties. Based on the experimental results, higher RHA contents had a generally negative effect on the fresh properties of the HFRC mixtures. Compressive strength values ranged from 53 to 72 MPa with various RHA and HF content. RHA replacement levels up to 20% had an insignificant effect on the strength development and dynamic modulus of the HFRC samples. However, the addition of HF improved splitting tensile strength, flexural strength, and dynamic modulus remarkably at all curing ages. Furthermore, the 91-day drying shrinkage was in the ranges of 0.032%–0.039% and 0.023%–0.034% using different RHA and HF levels, respectively. Increasing both RHA and HF contents significantly reduced drying shrinkage in the samples. Multivariable regression was also performed, clarifying that all tested results were consistent and had good correlations. The results of this study also provide a potentially effective use for abundantly available industrial waste products such as fly ash (FA) and RHA to promote the production of greener and more sustainable concrete.

Physical and chemical contributions of Rice Husk Ash on the properties of mortar

In this study, the role of a locally available rice husk ash (RHA) in reducing early-age shrinkage of high performance concrete (HPC) after evaluating its pozzolanic reactivity was evaluated. The X-ray diffraction (XRD) and energy dispersive X-ray (EDX) analyses were performed after burning rice husk to 700 and 950 oC. Presence of relatively high deposits of amorphous siliceous phases in RHA at 700 oC indicated its pozzolanic potential. Subsequently, this RHA was ground to desired fineness, followed by sieving through sieve No. 200. Eventually, the fine RHA was used as a substitute of cement in different percentages (10, 15 and 20%) to evaluate its influence in mitigating autogenous shrinkage in concrete. Prismatic concrete beams (100 mm x 100 mm x 800 mm) were cast to measure autogenous shrinkage along with cylinders (150 mm dia. x 300 mm height) to test compressive strength of concrete. The results indicated a slight increase in compression strength with addition of 10% RHA, which however, reversed and slightly reduced in concretes containing 15 and 20% RHA. Unlike strength results, the trend of autogenous shrinkage was rather uniform as the rate as well as the amount of early-age autogenous shrinkage continued to decrease with increasing percentage of RHA. Moreover, despite of reduced rate during first 24 hours, thereafter, the effect of 20% RHA on further reduction of autogenous shrinkage was insignificant and ended up only slightly lesser than the 15% RHA concrete at 7 days. Finally, the control cement sand mortar and mortar containing 15% RHA were cast to further validate the pozzolanic reactivity of RHA through scanning electron microscopy (SEM), EDX and thermogravimetric analysis (TGA) tests. An observation of reduced amount of calcium hydroxide (Ca(OH)2) in RHA mortar samples indicating its excellent pozzolanic potential when used as a partial substitute of cement in HPC.

Research on the use of Rice Husk Ash (RHA) in cement, concrete and mortar has been explored in different fronts in Nigeria with encouraging results. RHA is composed of silica, alumina, iron oxide, calcium oxide and some traces of other compounds. The combustion of RHA at optimum temperature established by researchers produces either amorphous or crystalline ash depending on the combustion temperature and type of burning. This paper tries to bring under one umbrella documented research reported in literature on the use of RHA in construction in Nigeria. Physical and chemical properties; consistency, setting time and flow of mixed paste are reported. Combustion process and optimum temperature has also been exclusively reported. Cement replacement with RHA, strength results on concrete, mortar, bricks and blocks; other properties reported are flexural and tensile strength, sorptivity and coefficient of water absorption.

Ultra-high-performance concrete with steel fibers (UHPC) stands out for its exceptional mechanical properties and high ductility. The addition of steel fibers improves the tensile strength, allowing for its use in the design of structural elements subject to bending. The use of rice husk ash (RHA) as a natural mineral addition in the UHPC mixture offers significant advantages in terms of environmental impact and mechanical properties. Therefore, this work experimentally investigates the effect of RHA as a partial replacement for active silica fume on the flexural tensile strength and compressive behavior of UHPC. Additionally, a parametric study was conducted to examine the impact of varying prism geometries on the flexural tensile strength of UHPC with and without CCR in ABAQUS version 6.14. The experimental results made it possible to calibrate the UHPC parameters using RHA for numerical simulations of UHPC behavior based on the concrete damaged plasticity (CDP) model. The results indicated an increase of 4% in the compressive strength and 20% in the flexural tensile strength of UHPC with the addition of RHA. Furthermore, the numerical extrapolations of the flexural tensile strength test show that increasing the dimensions of the prisms reduces the strength by up to 30% of UHPC with RHA, evidencing the influence of geometry on the results.

The research studies about the development and characterization of a rice husk ash (RHA)-reinforced polysulfide oligomer/epoxy resin (PSO/EP) composite for use in automotive applications. To improve mechanical and chemical properties, RHA is a silica-rich agricultural byproduct which was incorporated at different loadings (0.5,1, 2 wt%). The composite was prepared using a modified thiokol method for PSO and with universal EDP-2 epoxy resin which was supplied by Altai Prom Polymer. Many characterizations have been done. Crosslinking between the thiol groups of PSO and epoxy resin was confirmed by FTIR analysis, while XRD showed a hybrid structure that was primarily amorphous polymer networks and crystalline silica from RHA. SEM showed a consistent RHA distribution with strong adhesion between the filler and matrix. Mechanical testing demonstrated optimal performance at 1 wt% RHA, providing a tensile strength increase of 5% and a flexural strength increase of 49% compared to unfilled epoxy, due to RHA’s ability to transfer stress. Increased RHA loadings (2 wt%) caused agglomeration and reduced strength. The composite demonstrated good thermal stability, resistance to automotive fluids, and low VOC emissions. Windshield adhesives (with a shear strength enhancement), underbody coatings (which offer corrosion resistance through RHA’s SiO₂ barrier), and engine gaskets (with a compression set of less than 10%) are all potential automotive applications. RHA is underscored in the research as a sustainable, inexpensive filler that reconciles flexibility (PSO) and rigidity (EP), providing a practical substitute for synthetic fillers in lightweight automotive parts.

An efficient method to address environmental issues and lower the price of concrete in modern construction is to use rice husk ash to partially replace cement in the manufacturing of concrete for rural roads. This study used experimental data to calculate the modulus of elasticity, compressive strength, and flexural tensile strength of cement concrete utilizing rice husk ash. Based on the obtained results, the strength parameters of concrete decreased as the rice husk ash content increased. When replacing cement with rice husk ash with the contents of 5%, 15%, 20%, and 25%: the compressive strength of concrete decreased by 5,41%, 6,51%, 7,49% and 13,91%, flexural tensile strength decreased by 0,47%, 1,18%, 2,61%, and 4,98%, and the elastic modulus of concrete decreased by 5,51%, 10,19%, 11,85%, and 12,4%, respectively, compared to the control specimen. However, all mixture types have a compressive strength of M300 grade and flexural tensile strength, Rku > 4,0 MPa. This indicates that the mixtures containing rice husk ash are suitable to be used as a surface layer for all grades of rural roads and highways with light traffic without heavy vehicles with a single axle >100kN in circulation.

Combine the use of rice husk ash and quarry waste for sustainable masonry blocks: mechanical characteristics, durability and eco-benefits

The cost effectiveness of upgrading gravel roads to a sealed standard has challenged road authorities to make optimum use of naturally occurring materials such as laterites as sub-base and base materials. Untreated laterites have presented problems such as pavement swelling and depression in road construction. This research seeks to assess and stabilise the geotechnical properties of some lateritic soils in Tarkwa using Rice Husk Ash for road construction purposes. Lateritic soils obtained from Akoon and Kwabedu are labelled AK and KW respectively. Rice husk was obtained from Ejisu in the Ashanti Region of Ghana and burnt to ashes. The lateritic soils were subjected to Atterberg limits, compaction and California Bearing Ratio tests. The lateritic soils were subsequently mixed with Rice Husk Ash in varying percentages of 5 % and 10 % and the influence of Rice Husk Ash on the soils was determined for Atterberg limits, compaction and California Bearing Ratio tests. The Plasticity Index of sample AK and KW were 20.18 % and 11.3 % respectively. At 10 % addition of Rice Husk Ash, the Plasticity Index of AK reduced to 8.02 % and KW to 5.22 %. The Maximum Dry Density of sample AK reduced from 2.22 Mg/m 3 at 0 % Rice Husk Ash to 1.88 Mg/m 3 at 10 % Rice Husk Ash. The Optimum Moisture Content of AK increased from 13.72 % to 19.9 %. The Maximum Dry Density of sample KW reduced from 1.88 Mg/m 3 at 0 % Rice Husk Ash to 1.73 Mg/m 3 at 10 % Rice Husk Ash whiles the Optimum Moisture Content increased from 14.72 % at 0 % Rice Husk Ash to 19.9 % at 10 % Rice Husk Ash. The California Bearing Ratio value for sample AK is 24 % and for sample KW is 43 %. At 10 % addition of Rice Husk Ash, the California Bearing Ratio for AK and KW increased to 61 % and 78 % respectively. The lateritic soils from Kwabedu are adjudged suitable for sub-base and lateritic soils from Akoon are not suitable for sub-base. Rice Husk Ash effectively stabilised the lateritic soils for base course for low traffic roads.

Rice stalk fiber and rice husk ash are agricultural by-products, which are available worldwide in large quantities. There is, however, no information about suitability of the rice stalk fiber and rice husk ash combination for the production of fiber-cement composites in the open literature. This paper presents a parametric experimental study, which investigates the potential use of rice stalk fiber (as reinforcement) and rice husk ash (as cement replacement) admixtures for producing a lightweight fiber-cement composite as a building material. Three levels of fibrous materials, namely 10, 25 and 40 wt% were mixed with 0, 10 and 20 wt% of rice husk ash. Effects of these variable parameters on the mechanical (modulus of rupture, modulus of elasticity and internal bond) and physical properties (water absorption and thickness swelling) of the samples were studied. The results showed the effect of high-level replacement of rice stalk fiber with rice husk ash does not exhibit a sudden brittle fracture even beyond the failure loads, indicating high energy absorption capacity of the composites. Based on the findings of this work, the water absorption and thickness swelling of the composites increased with the increasing rice stalk fiber content in the samples from 10 to 40 wt%. On the other hand, modulus of rupture and modulus of elasticity of the boards were enhanced with increase in the percentage of rice stalk fiber. Boards having 25 wt% rice stalk fiber exhibited the highest internal bond strength. However, addition of rice stalk fiber and rice husk ash reduced the internal bond strength. Moreover, boards made with rice stalk fiber had superior properties compared to boards made with a mixture of hardwood fibers.

In this study, it is aimed to investigate the influence of rice husk ash, which is a waste by-product of industrial production, on ultrasonic pulse velocity, compressive strength, flexural strength and high temperature endurance of the metakaolin-based geopolymer mortar. For this, the sand was substituted by rice husk ash (RHA) at the rate of 25%, 50% and 75% by wt. in the production of geopolymer mortar. A total of 4 series of metakaolin-based geopolymer mortars (reference series and three series with RHA substitution) were produced. In this study, the geopolymer, in other words, the binder of the mortar was produced by metakaolin and ground granulated blast furnace slag reacting with the mixture of sodium hydroxide (12M NaOH) and sodium silicate (Na2SiO3) solutions. The ratio of metakaolin and reactant mixture (12M NaOH + Na2SiO3) was determined for each series following the preliminary experiments. On the specimens produced as 50 mm cube and 40 x 40 x 160 mm prism, the intended experiments were carried out after specimens underwent curing in a dry oven at 60oC during 72 h and gained strength. The results showed that RHA could be used as a filling material in metakaolin-based geopolymer mortars, and metakaolin-based geopolymer mortars with 50% RHA substitution can be an alternative to the pure metakaolin-based mortar.

Effect of rice husk ash on mechanical properties of concrete containing crushed seashell as fine aggregate