Physical and mineralogical properties of calcined common clays as SCM and their impact on flow resistance and demand for superplasticizer

Sposito, Ricarda; Maier, Matthias; Beuntner, Nancy; Thienel, Karl‐Christian

doi:10.1016/j.cemconres.2022.106743

Cited by 30 publications

(10 citation statements)

References 61 publications

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“…The limits for the self-compactability of mortar specified in [4,30,31] were reviewed and modified to cover the use of CC in the production of SCC. The characterization of the CC was described thoroughly in [33][34][35]. Tables 1 and 2 show the chemical and physical characteristics of the powder materials, respectively.…”

Section: Introductionmentioning

confidence: 99%

Suitability of Clinker Replacement by a Calcined Common Clay in Self-Consolidating Mortar—Impact on Rheology and Early Age Properties

2022

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The use of a high amount of calcined clays as cement replacement presents a great challenge in designing self-consolidating concrete. This current attempt evaluates the influence of cement replacement with up to 40 vol.% by a calcined common clay (CC), dominated by 2:1 phyllosilicates in combination with a fixed limestone powder (LP) content on fresh and hardened properties of self-consolidating mortar (SC-M). The fresh properties of SC-M were investigated by mini-slump flow, V-funnel and rotational viscometer measurements. Setting and hardening behavior were observed via dynamic modulus of elasticity and plastic shrinkage. Hydration mechanisms were determined by isothermal calorimetry and thermal analysis. Hardened properties of SC-M were evaluated using compressive strength tests and mercury intrusion porosimetry (MIP). The results revealed a decreased rate of deformability in SC-M when cement is substituted increasingly by CC and a rising superplasticizer (SP) demand, but indicated an improved stability of SC-M even at a higher dosage of SP and hardly any impact on the setting behavior. CC enhanced the precipitation of monocarboaluminate phases and thereby refined the pore size distribution of the binder matrix. SC-M can be produced with up to 40 vol.% CC as cement replacement without having effect on its 28 days mechanical properties.

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Section: Introductionmentioning

confidence: 99%

Suitability of Clinker Replacement by a Calcined Common Clay in Self-Consolidating Mortar—Impact on Rheology and Early Age Properties

2022

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“…The determined physical parameters of the NCCs included the particle density measured using a helium pycnometer, according to DIN EN ISO 17892-3 [ 50 ], the BET specific surface area measured using a HORIBA SA-9600 series surface area analyzer, according to DIN ISO 9277 [ 51 ], particle size distribution (PSD) determined using laser light diffraction (Bettersizer, 3P instrument) [ 30 ], and water demand based on the Puntke method [ 52 ].…”

Section: Methodsmentioning

confidence: 99%

“…This is evidenced by a strong influence of the early clinker hydration in CC blended systems [ 26 , 27 , 28 ]. The released aluminum exploits its full potential, especially in the presence of LP [ 18 , 29 , 30 ]. When CC and LP are blended and used as a substitute for clinker, they promote the formation of monocarboaluminate/hemicarboaluminate AFm phases and densify the concrete microstructure, which in turn have positive effects on the mechanical and durability properties of mortar and concrete [ 18 , 31 , 32 , 33 ].…”

Section: Introductionmentioning

confidence: 99%

Calcined Clays from Nigeria—Properties and Performance of Supplementary Cementitious Materials Suitable for Producing Level 1 Concrete

2023

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In this work, four naturally occurring (two kaolinite-rich and two smectite-rich) clay samples were collected from different areas around the Ashaka cement production plant, located in Gombe State, Nigeria and calcined in a laboratory. The mineralogical characterization of the clays was carried out by XRD. The hydration kinetics of the calcined clay–cement systems were monitored by isothermal calorimetry. Workability was determined using the flow table method. The reactivity of the calcined clays was determined from the solubility of Si and Al ions and the strength activity index. All calcined clays studied met the requirements of ASTM C618 for the use of natural pozzolans as a partial replacement for hydraulic cement. The metasmectite clays yielded a higher specific surface area, increased water demand, and less reactive Si and Al ions compared to the metakaolin clays. The two calcined clay groups require the addition of superplasticizer to achieve a workability class similar to the Portland cement mortar system. They can be used to replace Portland cement at replacement levels of up to 45%, in combination with limestone powder to form an LC3 cement, thereby achieving at least a “Level 1” reduction in greenhouse gas emissions.

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“…The recorded torque was used to estimate the yield stress (τ 0 ) and plastic viscosity (η) of the SCC according to the Bingham model [47,48] using Equation (3). The flowability retention of the SCC is monitored by calculating flow resistance of the SCC mixtures over time (area under curve) obtained by plotting the torque against the velocity as described previously by [26].…”

Section: Rheology and Flowability Retention Assessmentmentioning

confidence: 99%

Properties of Self-Compacting Concrete Produced with Optimized Volume of Calcined Clay and Rice Husk Ash—Emphasis on Rheology, Time Dependent Workability and Durability

Muhammad¹,

Thienel²

2023

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Durability of concrete requires a dense microstructure which can be achieved by using self-compacting concrete (SCC). Both calcined clay (CC) and rice husk ash (RHA) are promising supplementary cementitious materials (SCMs) that can partially replace cement, but their use in SCC is critical due to their higher water demand and specific surface area (SSA) compared to cement. Empirical method of SCC design was adopted considering the physical properties of both CC and RHA. The influence of partially substituting cement at 20 vol-% with binary and ternary blends of CC and RHA were investigated. The fresh properties of SCC were investigated using a variety of tests. The time dependent workability was monitored by plunger method and flow resistance determined based on the rheological measurements of SCC. The evolution of the hydrate phases of the binder in SCC was determined by thermogravimetric analysis, while the durability was evaluated by rapid chloride migration test. Cement partial replacement with 20 vol-% CC has no significant effect on SCC fresh, time dependent, compressive strength and durability properties. 20 vol-% RHA on the other hand requires higher dosage of SP to achieve self-compactability and increased the viscosity of SCC. Its workability retention is only up to 30 min after mixing and exhibited higher flow resistance. It consumes more CH and improves compressive strength and chloride resistance of SCC. The ternary blending with CC and RHA yielded better fresh SCC properties compared to the binary blend with RHA, while an improved chloride penetration resistance could be achieved compared to binary CC blend.

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Physical and mineralogical properties of calcined common clays as SCM and their impact on flow resistance and demand for superplasticizer

Cited by 30 publications

References 61 publications

Suitability of Clinker Replacement by a Calcined Common Clay in Self-Consolidating Mortar—Impact on Rheology and Early Age Properties

Suitability of Clinker Replacement by a Calcined Common Clay in Self-Consolidating Mortar—Impact on Rheology and Early Age Properties

Calcined Clays from Nigeria—Properties and Performance of Supplementary Cementitious Materials Suitable for Producing Level 1 Concrete

Properties of Self-Compacting Concrete Produced with Optimized Volume of Calcined Clay and Rice Husk Ash—Emphasis on Rheology, Time Dependent Workability and Durability

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