Synergistic effects of supplementary cementitious materials in limestone and calcined clay-replaced slag cement

2021 ◽  
Vol 282 ◽  
pp. 122648
Author(s):  
Han Wang ◽  
Pengkun Hou ◽  
Qinfei Li ◽  
Samuel Adu-Amankwah ◽  
Heng Chen ◽  
...  
Keyword(s):  
Synergistic Effects ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Slag Cement ◽  
Calcined Clay

Research Progress on the Hydration of Portland Cement with Calcined Clay and Limestone

2021 ◽  
Vol 1036 ◽  
pp. 240-246
Author(s):  
Jin Tang ◽  
Su Hua Ma ◽  
Wei Feng Li ◽  
Hui Yang ◽  
Xiao Dong Shen
Keyword(s):  
Mechanical Properties ◽  
Portland Cement ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Research Progress ◽  
Hydration Reaction ◽  
Hydration Products ◽  
Early Hydration ◽  
Calcined Clay ◽  
Dense Microstructure

The use of calcined clay and limestone as supplementary cementitious materials, can have a certain influence on the hydration of Portland cement. This paper reviewed the influence of limestone and calcined clay and the mixture of limestone and calcined clay on the hydration of cement. Both limestone and calcined clay accelerate the hydration reaction in the early hydration age and enhance the properties of cement. Limestone reacts with C3A to form carboaluminate, which indirectly stabilized the presence of ettringite, while calcined clay consumed portlandite to form C-(A)-S-H gel, additional hydration products promote the densification of pore structure and increase the mechanical properties. The synergistic effect of calcined clay and limestone stabilize the existence of ettringite and stimulate the further formation of carboaluminate, as well as the C-(A)-S-H gel, contributed to a dense microstructure.

Performance of Impure Calcined Clay as a Pozzolan in Concrete

2020 ◽  
pp. 036119812095314
Author(s):  
Khashayar Jafari ◽  
Farshad Rajabipour
Keyword(s):  
Portland Cement ◽  
Drying Shrinkage ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Strength Development ◽  
Natural Pozzolan ◽  
Quartz Content ◽  
Calcined Clay ◽  
Air Content ◽  
Sand And Gravel

Supplementary cementitious materials (SCMs) are natural or industrial by-product materials which are used to improve the performance, durability, and sustainability of concrete mixtures. Motivated by the recent reports on shortage of conventional SCMs, impure calcined clays (CCs) are receiving attention as abundant alternative pozzolans for concrete. In this study, a clay slurry resulting from washing aggregates in a commercial sand and gravel pit was investigated. This source clay was dried and calcined, and the properties and pozzolanic performance of the resulting CC was evaluated. It was observed that despite having a large (>50%wt.) inert quartz content, the CC met all ASTM C618-19 (AASHTO M295) requirements for natural pozzolan. A pavement-grade concrete mixture containing 20%CC as a cement replacement (by weight) produced desired workability and fresh and hardened air content. Strength development was slightly below the control. The use of CC improved the durability of concrete with respect to chloride penetration, alkali–silica reaction, and drying shrinkage in comparison with a control (100% Portland cement) mixture. In addition, ternary limestone-calcined clay–cement and slag-calcined clay–cement mortar mixtures showed excellent strength development while replacing nearly 50% of the Portland cement.

scholarly journals Portland Cements with High Content of Calcined Clay: Mechanical Strength Behaviour and Sulfate Durability

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4206 ◽  
Author(s):  
Carlos H. Aramburo ◽  
César Pedrajas ◽  
Rafael Talero
Keyword(s):  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Chemical Effect ◽  
Portland Cements ◽  
Calcined Clay ◽  
Blended Cements ◽  
Sulfate Resistance ◽  
Type Iv ◽  
Mechanical Strengths ◽  
Mineralogical Compositions

Calcined clay has become the supplementary cementitious materials with the greatest potential to reduce the clinker/cement. In this research, the mechanical strengths and sulphate resistance of blended cements with a high content of calcined clay as a pozzolanic addition were evaluated to demonstrate that these cements could be designed as CEM (cement) type IV/A-SR and IV/B-SR cements by the current European standard UNE-EN 197-1: 2011. The blended cements were prepared by two Portland cements (P1 and PY6) with different mineralogical compositions and a calcined clay. The level of replacement was greater than 40% by weight. The results obtained confirm the decrease in the mechanical strengths and the increase in the sulfate resistance of the two Portland cements when they are replaced by calcined clay at a level of replacement greater than 40%. These results are a consequence of the chemical effect from the pozzolanic activity of the calcined clay. Therefore, there is an important decrease in portlandite levels of paste liquid phase that causes the increase in sulfate resistance and the decrease of the mechanical strengths.

Development of Geopolymer Mortar for Field Applications

2018 ◽  
Vol 272 ◽  
pp. 280-283
Author(s):  
Remington G. Reed ◽  
Jospeh Daniels III ◽  
W. Micah Hale
Keyword(s):  
Fly Ash ◽  
Chemical Constituents ◽  
Carbon Dioxide Emission ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Total Carbon ◽  
Laboratory Research ◽  
Slag Cement ◽  
Waste Products ◽  
Heat Curing

In recent years there has been an increased demand for environmentally conscious and sustainable construction materials. One such material is “geopolymer” or “alkali-activated” binder. Current industry practice uses ordinary portland cement (OPC) in combination with supplementary cementitious materials as binder in concrete and mortar. Cement production is very energy intensive and accounts for approximately 10 percent of the total carbon dioxide emission in the world. In geopolymer materials, OPC is replaced with waste materials such as fly ash or slag cement along with a chemical activator. When supplied with additional chemical constituents, the aluminate and silicate present in fly ash or slag cement arrange into a polymeric structure with similar properties to hydrated cement. Proper application of this material can reduce, or even replace, the use of OPC in concretes and mortars. In addition to the cutback in OPC and the use of waste products, geopolymer materials require less water for curing and are shown to have increased resistance to chemical attack. While this product offers a “green” alternative to OPC, it is a new technological concept. Fly ash variability creates inconsistencies in quality control and chemical content. The chemical activators used to facilitate polymerization are often quite expensive and dangerous to use. Additionally, heat curing can be necessary for a geopolymer material to achieve specified compressive strength. Present limitations warrant extensive research and development to increase practicality of geopolymer materials for field implementation. In order to aid in the design and use of geopolymer materials, it is important that laboratory studies fully address the use of less than ideal materials and conditions in the creation of geopolymer. By using low cost materials and avoiding heat curing, laboratory research on geopolymer mortar can function as a means of developing a material that can be readily adopted into practice.

scholarly journals Properties of Western Cape Concretes with Metakaolin

2018 ◽  
Vol 199 ◽  
pp. 11011
Author(s):  
Alice T. Bakera ◽  
Mark G. Alexander
Keyword(s):  
Dilution Effect ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Superior Performance ◽  
Alkali Silica Reaction ◽  
Western Cape ◽  
Western Cape Province ◽  
Calcined Clay ◽  
Global Demand ◽  
Strength And Durability

A global demand for affordable, sustainable, and durable concrete has resulted in growing use of Supplementary Cementitious Materials (SCMs). In the Western Cape Province of South Africa, the readily available SCM is Granulated Ground Corex Slag (GGCS), although fly ash can also be obtained. However, the availability of these SCMs, particularly GGCS, is subject to market and other extraneous factors, and this may render them vulnerable as sources of SCM for concrete. This points to the need for innovation and investigating other potential SCMs which are economically and environmentally effective. Metakaolin, a high-grade type of calcined clay, emerges as a possible potential future SCM in the Western Cape. This study aimed at investigating the influence of a locally available metakaolin on mechanical (compressive and tensile strength), and durability (concrete penetrability and potential to mitigate Alkali Silica Reaction (ASR)) properties of Western Cape concrete. In comparison to GGCS, concretes with metakaolin showed superior performance in both mechanical and durability properties. This was attributed to its role in concrete in terms of accelerating hydration reactions, pozzolanic activity, and dilution effect. Metakaolin can therefore be regarded as a beneficial substitute for GGCS in Western Cape concrete. However, questions that remain include cost-effectiveness, and the awareness and willingness of industry to incorporate this material.

Assessment of Cuban Kaolinitic Clays as Source of Supplementary Cementitious Materials to Production of Cement Based on Clinker – Calcined Clay – Limestone

2017 ◽  
pp. 21-28
Author(s):  
Roger S. Almenares Reyes ◽  
Adrián Alujas Díaz ◽  
Sergio Betancourt Rodríguez ◽  
Carlos Alberto Leyva Rodríguez ◽  
José Fernando Martirena Hernández
Keyword(s):  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Calcined Clay

scholarly journals Synergistic Effects of Air Content and Supplementary Cementitious Materials in Reducing Damage Caused by Calcium Oxychloride Formation in Concrete

2021 ◽  
Author(s):  
Nima Hosseinzadeh ◽  
Prannoy Suraneni
Keyword(s):  
Synergistic Effects ◽  
Visual Assessment ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Cement Pastes ◽  
Freeze Thaw ◽  
Air Content ◽  
Concrete Damage ◽  
High Concentrations ◽  
Pavement Damage

Pavement damage occurs in cold-region concrete exposed to high concentrations of calcium chloride (CaCl2). The damage is caused by a combination of conventional freeze-thaw damage and the formation of a deleterious phase known as calcium oxychloride from a reaction between CaCl2 and calcium hydroxide in the concrete. Much research has focused on calcium oxychloride mitigation in cement pastes, but not on concrete damage due to calcium oxychloride. In this study, the synergistic roles of air and supplementary cementitious materials (SCMs) in reducing damage in concrete exposed to high concentrations of CaCl2 and freeze-thaw conditions is studied. Concrete mixtures were made with different SCM replacement levels and air contents ranging from 1.8 to 8.0% and immersed in 25% CaCl2 solutions and subject to freeze-thaw cycles (-8 °C to 25 °C) for 600 days. Bulk resistivity and visual assessment of damage were found to be excellent descriptors of the damage progression. Damage was reduced as the SCM content and air content was increased. Mixtures which had 20% SCM and 8% air and mixtures which had 35% SCM and more than 4% air showed strong durability against damage due to calcium oxychloride formation.

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