Effect of Particle Size of Residual Rice-Husk Ash in Consumption of Ca(OH)2

Rêgo, João Henrique da Silva; Nepomuceno, A. A.; Figueiredo, Enio Pazini; Hasparyk, Nicole Pagan; Borges, Luciana Diniz

doi:10.1061/(asce)mt.1943-5533.0001136

Cited by 28 publications

(13 citation statements)

References 23 publications

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“…This phenomenon may be associated with the reduced formation of ettringite caused by the interactions between calcium, sulfate, aluminate, and hydroxyl ions with water (Mehta and Monteiro [2]), and could be explained by the reaction between the sand powder and constituents of the recovered cement when subjected to hydration. This hypothesis reinforces the theory of the supplementary behavior of sand power in cement, as well as the reactivity increase caused by its comminution (Rêgo et al [32]).…”

Section: Figuresupporting

confidence: 89%

Hydraulic binder obtained from recycled cement and sand powder

Menezes

Silva

Figueiredo

et al. 2018

Rev. IBRACON Estrut. Mater.

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Environmentally eco-efficient concrete is currently a popular choice of construction material. Reviewing relevant literature indicates that heating of cement paste can remove hydrating water, and that quartz sand of appropriate granulometry can act as a supplementary cementitious material; however, there have been virtually no reports on the reuse of these materials as alternative binders. This work evaluates the phases present in cementitious compounds produced with binders obtained by thermomechanically treating cement pastes with and without a 15% substitution of quartz sand powder (specific surface area 37.4 m²/g), referred to as RCQ and recycled cement RC, respectively. Testing included thermogravimetric analysis (performed with stripped gases), X-ray diffraction, and scanning electron microscopy with phase identification. The obtained data indicated RC cement paste possesses a predominantly ettringite microstructure, whereas the presence of calcium hydroxide and hydrated calcium silicate predominates in RCQ paste.

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Section: Figuresupporting

confidence: 89%

Hydraulic binder obtained from recycled cement and sand powder

Menezes

Silva

Figueiredo

et al. 2018

Rev. IBRACON Estrut. Mater.

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“…According to Cordeiro et al [4], the increase of consumption of Ca(OH) 2 in pastes with residual RHA has a strong correlation with the reduction of particle size of RHA and this behavior is explained by the increased external specific surface area. Rêgo et al [21] corroborated this explanation and added that in the case of RHAs with a low content of amorphous silica, the reduction of the particle diameter by ultrafine grinding increases their amorphous silica content and changes the local structure of the silicon atoms, which in turn increases the consumption of Ca (OH) 2 .…”

Section: Characterization Of the Residual Rhas Produced In Brazilmentioning

confidence: 59%

“…Reducing the particle size of RHAs with low amorphous silica content influences their pozzolanic activity [7,8] and increases the their Ca(OH) 2 consumption [4,21]. The ultrafine grinding of residual RHA, that reduces the average particle diameter below 10 lm, was found to be sufficient for generating high pozzolanic activity [1,12].…”

Section: Introductionmentioning

confidence: 99%

Microstructure of cement pastes with residual rice husk ash of low amorphous silica content

Rêgo

Nepomuceno

Figueiredo

et al. 2015

Construction and Building Materials

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“…The pozzolanic reaction of the SCMs improved the microstructure of the mortar bars and contributed to the reduction of porosity and permeability. This occurs due to the action of several mechanisms that contributes to the damage limit by ASR [3], [8]- [10], [44].…”

Section: X-ray Diffraction (Xrd)mentioning

confidence: 99%

“…It is clear that mortar bars containing RHA and SF have higher amounts of SiO 2 and CaO than in control samples (Table 3), which may indicate pozzolanic activity and higher formation of C-S-H. Shafaatian et al [48] demonstrated that the ratio CaO/SiO 2 of the hydrated material is a good parameter to indicate the mitigative potential for ASR development. Due to the pozzolanic reaction, the C-S-H pozzolanic has a small amount of Ca and, therefore, generates a ratio CaO/SiO 2 inferior to the C-S-H formed by hydrated cement without SCMs [10], [44], [49]. The absorption of alkalis by C-S-H changes due to its surface charge, and this depends on the CaO/SiO 2 .…”

Section: Sem/edxmentioning

confidence: 99%

Rice husk ash as supplementary cementing material to inhibit the alkali-silica reaction in mortars

Langaro

Santos

Medeiros

et al. 2021

Rev. IBRACON Estrut. Mater.

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Alkali-silica reaction (ASR) is one of the most harmful distress mechanisms that affects the durability of concrete worldwide. Yet, it has been found that ASR-induced expansion and distress may be prevented by the appropriate use of supplementary cementing materials (SCMs). Recent studies suggest that rice husk ash (RHA), a by-product of the rice production, may present promising performances as a pozzolanic material and to enhance the durability of blended mixtures. There are many controversial studies regarding the use of RHA and how its properties directly affect the performance and durability of concretes and mortars. The present study aims to evaluate the influence of the RHA on ASR through the accelerated mortar bar test (AMBT), X-Rays Diffraction (XRD), Thermogravimetric Analysis (TG), Mercury Intrusion Porosimetry (MIP) and Scanning Electron Microscopy (SEM). To validate the obtained data, the results were compared with mortars made of a well-known SCM (silica fume) which has distinguished behaviour against ASR. The results indicate that, besides the silica fume mortars have showed better results, the use of RHA suggests promising results to mitigate the ASR, yet, further analysis on concrete prims test should be carried out to fully validate the use of RHA to enhance the durability of the concrete. The RHA finesses and its particle size were the most important properties in the SCM performance.

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Effect of Particle Size of Residual Rice-Husk Ash in Consumption of Ca(OH)2

Cited by 28 publications

References 23 publications

Hydraulic binder obtained from recycled cement and sand powder

Hydraulic binder obtained from recycled cement and sand powder

Microstructure of cement pastes with residual rice husk ash of low amorphous silica content

Rice husk ash as supplementary cementing material to inhibit the alkali-silica reaction in mortars

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