Performance of Rice Husk Ash as Supplementary Cementitious Material after Production in the Field and in the Lab

Abstract

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 large quantities, and as additive for high performance concrete. Thus, the paper presents a comparison between RHA produced under rudimentary conditions in a self-made furnace in the rural Bagamoyo, Tanzania and under controlled laboratory conditions at the Technical University of Munich, Germany, with different combustion methods and temperatures. In a second step, RHA was ground to reach particle size distributions comparable to cement. In a third step, cement pastes were prepared with 10%, 20% and 40% of cement replacement, and compared to the performance of plain and fly ash blended cement pastes. The results show that controlled burning conditions around 650 °C lead to high reactivity of silica and, therefore, to good performance as SCM. However, also the RHA burnt under less controlled conditions in the field provided reasonably good properties, if the process took place with proper burning parameters and adequate grinding. The knowledge can be implemented in the field to improve the final RHA performance as SCM in concrete.

Reactivity and Pozzolanic Properties of Biomass Ashes Generated by Wheat and Soybean Straw Combustion

“…Moreover, the grinding time affects the final pozzolanic performance remarkably, as higher surface area values of the ash lead to more reactive sites for a pozzolanic reaction. Similar trend was observed by Thiedeitz et al [ 72 ].…”

Prediction of Compressive Strengths for Rice Husks Ash incorporated concrete, Using Neural Network and Reviews

“…RHA Composition, Applicability and Effects Study by Thiedeitz et al [5] indicated specific surface area based on BET adsorption method for rice husk ash (grounded for 20 seconds with 20 Hertz frequency) and cement CEM 1 42.5R were 128 m 2 /g and 1.24m 2 /g respectively. Study by Fernandes et al [33] on RHA from thermoelectric company in Brazil, indicated mean diameter of 19.56 + 0.49 µm, specific weight of 2.22 + 0.0028 g/cm 3 and specific area of 11.35 + 0.21 m 2 /g, for RHA described in table 1.…”

“…Study by Thiedeitz et al [5] generally 40% cement replacement with RHA or fly ash indicated strong reduction of compressive strength, whereas 20% cement replacement with RHA or fly ash could even improve performance. Study by Sala et al [6] for 10% replacement by weight of metakaolin, thermal RHA and chemical treated rice ash with raw materials from Colombia indicated that pozzolanic material incorporation increased concrete compressive strength.…”

“…Utilization of waste from rice production/processing for construction could provide alternative sustainable materials, while reducing the solid waste burden. According to Thiedeitz et al [5], as renewable resource rice husk provides construction materials constantly, there is need for investigation on possibility of each ecologically friendly material for building. Effective predictive techniques for properties with concrete incorporated with RHA could be a step towards better structural decisions and development of proper codes of practices.…”

Silanization of SiO2 Decorated Carbon Nanosheets from Rice Husk Ash and Its Effect on Workability and Hydration of Cement Grouts

“…In another work, Franceschini et al prepared covalently bonded polymer C–S–H composite with the formation of covalent linkages between polymer and C–S–H phases by grafting trialkoxysilane (T-silane) and methyldialkoxysilane (D-silane) to the polymer chains [ 19 ]. To sum up, there are some attempts for the development of cement mixes by using rice husk ash as an alternative additive and direct or partial replacing with silica [ 20 , 21 , 22 , 23 ] and also most of the published works are mostly focused on the enhancement of strength properties of cementitious composites [ 24 , 25 ]. Besides, the effect of functionalized RHA by silane coupling agents on thermal and mechanical properties of thermoplastic composites was investigated to improve interfacial interactions in the composite structure [ 26 ].…”