Limestone Calcined Clay Cements (LC3)

Karen Scrivener, Franco Alberto Zunino Sommariva
AMER CONCRETE INST, 2021
Article

The climate emergency requires the adoption of strategies and technologies that effectively reduce CO2 emissions in the short to midterm to keep the global temperature rise below 2 degrees C above pre-industrial levels. Concrete is the substance most consumed by humanity after water. The blended cements in which supplementary cementitious materials replace part of the energy-intensive clinker are the most realistic means to obtain large-scale CO2 reductions. Limestone calcined clay cements (LC3)-blended cements produced by the combination of limestone, calcined clays, and portland cement (OPC)-provides a solution that achieves equivalent mechanical performance to OPC, better durability against chloride, and alkali-silica reaction reduction of CO2 emissions by approximately 40%. Furthermore, it is cost-effective compared to OPC currently on the market. Due to the similarities with OPC, it is a material that can be adopted today using the same construction equipment and workforce worldwide.

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Effect of fineness in clinker-calcined clays-limestone cements

Adrian Alujas Diaz, Mathieu Antoni, Karen Scrivener, Leng Maday Vizcaino Andres

This paper looks at the effect of fineness of the different components in a blend containing 55% Portland cement, 30% calcined clay and 15% limestone. The calcined clay originates from a natural deposit in Cuba and contains less than 50% kaolinite. The particle size distribution (PSD) of each of the three components was varied by using different grinding times, and the consequences on heat release, strength development, pore structure and phase assemblage development were investigated up to 28 d. Higher fineness of both clinker and calcined clay can considerably improve compressive strength at all ages, while limestone fineness only plays a role at early age. The formation of carboaluminate hydrates owing to the combined addition of calcined clays and limestone is confirmed for this case of a mixed clay with moderate kaolinite content.

Ice Publishing2015

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Alkali Silica Reaction and Sulfate Attack: Expansion of Limestone Calcined Clay Cement

Aurélie Rosine Favier, Karen Scrivener

In this paper, two durability issues: Alkali Silica Reaction (ASR) and external sulfate attack were studied. The results of expansion were presented for a Normal Portland cement and a blended cement LC3 containing calcined clay and limestone as supplementary cementitious materials (SCMs). The systems containing SCMs did not expand after several years of exposure showing a high resistance to ASR and sulfate attack.

SPRINGER2018

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Calcined clay limestone cements (LC3)

Shashank Bishnoi, Karen Scrivener

The use of supplementary cementitious materials (SCMs) to replace part of the clinker in cement is the most successful strategy to reduce CO2 emissions in the global cement industry. However, limited supplies of conventional SCMs make it difficult to take this strategy further unless new types of SCMs become available. The only type of material available in the quantities needed to meet demand is clay containing kaolinite, which can be calcined to produce an effective SCM. Such clays are widely available in countries where most growth in demand for cement is forecast. Calcined clays have previously been used as pozzolans, but calcination makes the economics of substitution marginal in a conventional pozzolanic blend. The major innovation presented here is the possibility to make a coupled substitution of cement with calcined clay and limestone. This allows much higher levels of substitution. Blends where calcined clay is used as a pozzolan, typically have clinker contents around 65-70%. Combination of calcined clay with limestone allows higher levels of substitution down to clinker contents of around 50% with similar mechanical properties and improvement in some aspects of durability. The replacement of clinker with limestone in these blends lowers both the cost and the environmental impact.

PERGAMON-ELSEVIER SCIENCE LTD2018

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