Effect of the Nano-Ca(OH)2 Addition on the Portland Clinker Cooking Efficiency.

Azzurra Zucchini,Gianluca Polidori,Gabriele Lanzafame,Lucia Mancini,Francesco Vetere,Alessandro Di Michele,Serena Casagrande,Silvia Gentili,Alessandro Neri,Riccardo Vivani,Fabio Santinelli,Paola Comodi,Luca Bartolucci

doi:10.3390/ma12111787

Azzurra Zucchini, Gianluca Polidori + Show 11 more

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https://doi.org/10.3390/ma12111787

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Abstract

A new technology was tested to improve the cooking efficiency of the raw mixture for Portland clinker production by the use of nano-Ca(OH)2. A decrease in the free lime concentration after the firing of approximately 35% and 55% in the nano-added clinkers burned at 1350 °C and 1450 °C, respectively, with respect to the standard Portland clinkers was observed. Moreover, in the nano-added clinkers, a slight decrease in alite (C3S), of approximately 2–4 wt%, and increase in belite (C2S), of approximately 5–6 wt%, were observed. Despite these variations, the C2S and C3S abundance lies within the ranges for standard Portland clinkers. The results showed that the nano-addition leads to an increase of the raw mixtures’ cooking efficiency. The relatively low energy required for the clinker firing could be used to increase the plant productivity and decrease the CO2 emissions during clinker burning. The decrease of the work index of the clinkers produced by the use of the nano-Ca(OH)2 also contributes to the energy saving during clinker grinding. Differences were also found in the pore size distribution among nano-added clinkers and the standard Portland clinker. The smallest porosities with the modal volume lying in the class of 3 × 10−6 mm3 were found to increase by the use of nano-Ca(OH)2. However, the pore volumes higher than 2.0 × 10−5 mm3 decreased in the nano-added clinkers.

Highlights

Portland cement is currently one of the most used construction materials with the best compromise between the high demand and the associated low cost together with its high performance and flexibility [1]
500 nm nm perpendicular perpendicular to to (001), (001), which which confirms confirms the the results results obtained obtained from fromBET
With regard to the free lime, since CaO is a strong hydrophilic material, we considered Ca(OH)2 as a secondary product coming from the CaO hydration at ambient conditions

Summary

Introduction

Portland cement is currently one of the most used construction materials with the best compromise between the high demand and the associated low cost together with its high performance and flexibility [1]. It was estimated that global cement production rose up to ~4000 Mt·yr−1 in 2016 [2]. The base material for cement is the clinker. It is a mixture of clays and carbonates heated up to approximately 1450 ◦ C. Almost all the raw materials melt, and, as a consequence, primary minerals decompose and new minerals crystallize.

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