Contribution of rice husk ash to the properties of mortar and concrete: a review

In the last decade, the use of supplementary cementing materials has become an integral part of high strength and high performance concrete mix design. These can be natural materials, by-products or industrial wastes, or the ones requiring less energy and time to produce. Some of the commonly used supplementary cementing materials are fly ash, Silica Fume (SF), Ground Granulated Blast Furnace Slag (GGBFS) and Rice Husk Ash (RHA) etc. RHA is a by-product material obtained from the combustion of rice husk which consists of non-crystalline silicon dioxide with high specific surface area and high pozzolanic reactivity. It is used as pozzolanic material in mortar and concrete, and has demonstrated significant influence in improving the mechanical and durability properties of mortar and concrete. This paper presents an overview of the work carried out on the use of RHA as partial replacement of cement in mortar and concrete. Reported properties in this study are the mechanical, durability and fresh properties of mortar/concrete

Particle size effect on the permeability properties of nano-SiO2 blended Portland cement concrete.

In this study, nano-SiO2 has been used as a high reactive pozzolan to develop the microstructure of the interfacial transition zone between the cement paste and the aggregate. Mechanical tests of blended cement-based concretes exposed that in addition of the pozzolanic reactivity of nano-SiO2 (chemical aspect), its particle grading (physical aspect) also revealed considerable influences on the blending effectiveness. It was concluded that the relative permeability reduction (relative to the control concrete made with plain cement) is higher for coarser nano-SiO2 after 90 days of moisture curing. However, finer nano-SiO2 particles showed better effects in early ages. These phenomena can be due to the free spacing between mixture particles that was associated with the global permeability of the blended cement-based concretes. This article presents the results of the effects of particle size ranges involved in nano-SiO2 blended Portland cement on the water permeability of concrete. It is revealed that the favorable results for coarser nano-SiO2 reflect enhanced particle packing formation accompanied by a reduction in porosity and particularly in particle spacing after 90 days

The effects of lime solution on the properties of SiO2 nanoparticles binary blended concrete

In this study, the effects of SiO2 nanoparticles on both mechanical properties (compressive, split tensile and flexural strength) and physical properties (water permeability, workability and setting time) of binary blended concrete have been investigated. SiO2 nano-particles have been used as a partial cement replacement by 0.5, 1.0, 1.5 and 2.0 wt.%. Curing of the specimens has been carried out in water and lime solution for 7, 28 and 90 days after casting. For the specimens cured in water, the optimal replacement level of cement by SiO2 nanoparticles for producing concrete with improved strength, was set at 1.0 wt.%. However, by curing the specimens in lime solution, Portland cement could be advantageously replaced by 2.0 wt.% of SiO2 nanoparticles. It was concluded that the SiO2 nanoparticles can improve the filler effect and its ultra high pozzolanic activity causes more C–S–H gel formation when cured in lime solution. Although curing in the lime solution can reduce the strength of control concrete, Curing the specimens containing SiO2 nanoparticles in lime solution causes faster setting time together with higher strength and residence to water absorption

Porous concrete pavement containing nanosilica from black rice husk ash

Rice husk is a waste from the agricultural industry. It has been found that the main inorganic element in rice husk is silica. Rice husk ash (RHA) as a replacement material in the conventional concrete mixture has been widely studied around the world. However, there is a lack of documented research on nano production from RHA used as a replacement cement in porous concrete pavement mixtures. This study employed the top-down approach via dry grinding in a mechanical ball mill to generate a nano-black RHA (nano-BRHA). As a result, nano-BRHA was successfully generated with an optimum duration of 63 hours and median size of 66 nm. The results also indicated that the particle size of BRHA was significantly decreased with increasing grinding time. In addition, the morphology of the nano-BRHA changed with grinding duration. Finally, the use of nano-BRHA produced porous concrete pavement with good strength and permeability, and sound absorption

Method and composition for making watertight cement based concrete product utilizing silica nanoparticles and rice husk ash

A method of production of a watertight ternary blended concrete product to highly reduce multiple water absorption values includes the steps of providing a cement mortar mixture, introducing ultrahigh reactive activators to the cement mortar mixture to lower porosity by densifying the cement mortar mixture and accelerating multiple cement hydration particles. Particularly, the activators include multiple nanoparticles. The method further includes, mixing the cement mortar mixture and the multiple nanoparticles with an inorganic binder and water to form the concrete product

Influence of mixing methods of nano silica on the microstructural and mechanical properties of flax fabric reinforced geopolymer composites

© 2016 Elsevier LtdThis paper presents the effects of two mixing methods of nanosilica on physical and mechanical properties of flyash-based geopolymer matrices containing nanosilica (NS) at 0.5, 1.0, 2.0, and 3.0 wt%. Comparison is made with conventional mechanical dry-mix of NS with fly-ash and wet-mix of NS in alkaline solutions. The influence of NS on the flexural toughness of flax fabric (FF) reinforced geopolymer nanocomposites has also been reported. Physical and microstructural properties are investigated using X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy. Results show that generally the addition of NS particles improves the microstructure and increases flexural and compressive strengths of geopolymer nanocomposites. However, samples prepared using the dry-mix approach demonstrate better physical and mechanical properties when compared to wet-mix samples