Effect of alkali-activator and rice husk ash content on strength development of fly ash and residual rice husk ash-based geopolymers

Hwang, Chao‐Lung; Huynh, Trong‐Phuoc

doi:10.1016/j.conbuildmat.2015.10.025

Cited by 232 publications

(78 citation statements)

References 20 publications

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Section: Resultssupporting

confidence: 93%

“…Additionally, a part of RHA particles that are unreactive and not dissolved in the alkaline environment may act as filler material, therefore, reducing the voids/pores within the system and improving the brick strength. Similar findings were previously reported by several researchers [5,24,38]. However, further increasing (using a 10% interval of increase) the RHA content in the brick mixtures to between 20% and 50% of total binder resulted in the compressive strength values that were 17.8%, 35.1%, 42.2%, and 44.6% lower, respectively, than the RHA-free bricks.…”

Section: Strength Development Of Brick Samplessupporting

confidence: 90%

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Effect of residual rice husk ash on mechanical‐microstructural properties and thermal conductivity of sodium‐hydroxide‐activated bricks

Huynh

Hwang

Lin

et al. 2017

Env Prog and Sustain Energy

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This research compares the mechanical‐microstructural properties and thermal conductivity of the solid, green construction bricks that contain different percentages of sodium‐hydroxide‐activated residual rice husk ash and class‐F fly ash. The brick specimens were prepared following the guidelines of Vietnamese national standard in term of mixing, forming, and curing. Various percentages of rice husk ash (0%, 10%, 20%, 30%, 40%, and 50%) were added to a standard brick mixture in order to evaluate the influence of rice husk ash content on the strength development, void volume, water absorption capacity, bulk density, and thermal conductivity of the hardened bricks. Moreover, scanning electron microscopy was used to characterize surface morphologies of the brick samples. Further, the suitability of using a binder of rice husk ash and fly ash to produce alkali‐activated construction bricks was investigated. The bricks that were produced demonstrated generally good engineering performance and conformed to the relevant Vietnamese codes. Of particular note, the addition of rice husk ash influenced the properties of the bricks significantly, with brick strength peaking at a rice husk ash content of 10% and decreasing progressively at higher percentages. The findings from the present study support the efficacy of using a binder that contains rice husk ash and fly ash to produce green alkali‐activated construction bricks. © 2017 American Institute of Chemical Engineers Environ Prog, 37: 1647–1656, 2018

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Section: Resultssupporting

confidence: 93%

Section: Strength Development Of Brick Samplessupporting

confidence: 90%

Effect of residual rice husk ash on mechanical‐microstructural properties and thermal conductivity of sodium‐hydroxide‐activated bricks

Huynh

Hwang

Lin

et al. 2017

Env Prog and Sustain Energy

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“…In fact, in Figure 4 there is no direct correlation between the SH concentration and the UCS as it was expected from other published works (e.g., Xu and van Deventer, 2000;Cristelo et al, 2012). Alonso and Palomo (2001) and Hwang and Huynh (2015) have also reported some decrease in strength for NaOH concentration higher than 10 molal especially for low curing temperatures, as it was the case of this study. Alonso and Palomo (2001) state that high activator concentrations produce high pH in the liquid phase which favours anionic forms of silicate delaying polymerization while if the stable form was the molecular one (ortosilicic acid) the polymerization reaction is favoured.…”

Section: Unconfined Compression and Tensile Strengthsupporting

confidence: 69%

Mechanical and durability properties of a soil stabilised with an alkali-activated cement

Rı́os

Ramos

Fonseca

et al. 2017

European Journal of Environmental and Civil Engineering

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Alkali activated cements (AAC) have been extensively studied for different applications as an alternative to Portland cement (which has a high carbon footprint) and due to the possibility of including waste materials such fly ash or slags. However, few works have addressed the topic of stabilised soils with AAC for unpaved roads, with curing at ambient temperature, where the resistance to wetting and drying as well as the mechanical properties evolution over time is particularly relevant. In this paper, a silty sand was stabilized with an AAC synthetized from low calcium fly ash and an alkaline solution made from sodium silicate and sodium hydroxide. The evolution of stiffness and strength up to 360 days, the tensile strength, and the performance during wetting and drying cycles were some of the characteristics analysed. Strength and stiffness results show a significant evolution far beyond the 28 th curing day, but still with a reasonable short-term strength. Strength parameters deduced from triaxial tests were found to be very high with stress-strain behaviour typical of cemented soils. Durability properties related to resistance to immersion and wetting and drying cycles were found to comply with existing specifications for soil-cement, giving validity for its use as soil-cement replacement.

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“…It was reported that approximately 742 million metric tonnes of rice paddies are produced annually by the rice husk harvest by the end of 2013 , while the global annual production of RHA is estimated to be about 7500 thousand tonnes, with an approximate annual growth of 1.1% (Aprianti et al, 2015). RHA is a super-pozzolanic material due to its high silica content (85% to 90%), meaning it can be used as a SCM to produce high performance concrete and geopolymer cement as established by recent research (Hwang and Huynh, 2015;Alex et al, 2016;Sua-iam et al, 2016). Research conducted by Nimwinya et al (2016) used calcined water treatment sludge (WTS) and RHA, activated by alkali solutions of sodium hydroxide (NaOH) and sodium silicate (Na 2 SiO 3 ), to produce a sustainable geopolymer binder.…”

Section: Introductionmentioning

confidence: 99%

Development of a new ternary blended cementitious binder produced from waste materials for use in soft soil stabilisation

Jafer

Atherton

Sadique

et al. 2018

Journal of Cleaner Production

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Soil stabilisation using traditional binders such as Ordinary Portland Cement (OPC), has a serious negative environmental impact, specifically carbon dioxide (CO 2) emissions as a result of the manufacture of OPC. Because of this, the use of sustainable binders has become a critical issue to help reduce cement production through the use of by-product materials. This research seeks to develop a new ternary blended cementitious binder (TBCB) to replace cement for soft soil stabilisation. Different ternary mixtures containing wastes i.e., high calcium fly ash (HCFA), palm oil fuel ash (POFA) and rice husk ash (RHA) along with flue gas desulphurisation (FGD) gypsum used as a sulphate activator and grinding agent, were examined. The results illustrate that ternary mixtures improved the engineering and mechanical properties of stabilised soil. The results indicated that the plasticity index (PI) was reduced ACCEPTED MANUSCRIPT from 20.2 to 13.0 and the unconfined compressive strength (UCS) increased after 28 days of curing from 202kPa to 944kPa using the optimum non-FGD activated mixture. FGD contributed significantly by increasing the UCS to 1464kPa at 180 days of curing, which surpassed that for the reference cement (1450kPa), and by improving the soil consistency limits; where the PI decreased to 11.7 using TBCB compared with 14.5 for the soil treated with the reference cement. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis revealed substantial changes in the diffraction patterns and microstructure components of the TBCB paste over the curing period, confirming the formation of cementitious products. A solid, coherent and compacted structure was achieved after treatment with TBCB as evidenced by the formation of C-S-H, CH and ettringite.

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Effect of alkali-activator and rice husk ash content on strength development of fly ash and residual rice husk ash-based geopolymers

Cited by 232 publications

References 20 publications

Effect of residual rice husk ash on mechanical‐microstructural properties and thermal conductivity of sodium‐hydroxide‐activated bricks

Effect of residual rice husk ash on mechanical‐microstructural properties and thermal conductivity of sodium‐hydroxide‐activated bricks

Mechanical and durability properties of a soil stabilised with an alkali-activated cement

Development of a new ternary blended cementitious binder produced from waste materials for use in soft soil stabilisation

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