Properties of Chemically Combusted Calcium Carbide Residue and Its Influence on Cement Properties.

Hongfang Sun,Feng Xing,Shazim Memon,Yuan Fang,Biqin Dong,Zishanshan Li,Weiting Xu,Jing Bai

doi:10.3390/ma8020638

Hongfang Sun, Feng Xing + Show 6 more

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https://doi.org/10.3390/ma8020638

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Abstract

Calcium carbide residue (CCR) is a waste by-product from acetylene gas production. The main component of CCR is Ca(OH)2, which can react with siliceous materials through pozzolanic reactions, resulting in a product similar to those obtained from the cement hydration process. Thus, it is possible to use CCR as a substitute for Portland cement in concrete. In this research, we synthesized CCR and silica fume through a chemical combustion technique to produce a new reactive cementitious powder (RCP). The properties of paste and mortar in fresh and hardened states (setting time, shrinkage, and compressive strength) with 5% cement replacement by RCP were evaluated. The hydration of RCP and OPC (Ordinary Portland Cement) pastes was also examined through SEM (scanning electron microscope). Test results showed that in comparison to control OPC mix, the hydration products for the RCP mix took longer to formulate. The initial and final setting times were prolonged, while the drying shrinkage was significantly reduced. The compressive strength at the age of 45 days for RCP mortar mix was found to be higher than that of OPC mortar and OPC mortar with silica fume mix by 10% and 8%, respectively. Therefore, the synthesized RCP was proved to be a sustainable active cementitious powder for the strength enhanced of building materials, which will result in the diversion of significant quantities of this by-product from landfills.

Highlights

At present, the construction industry is encountering the challenge of incorporating sustainability into their production processes, either by searching for or incorporating new raw materials and products that are more environmental friendly and/or contributing towards the reduction of CO2 emissions into the atmosphere
Since the properties of synthesized products are usually determined and affected by the raw materials, the raw materials used for manufacturing reactive cementitious powder (RCP) were characterized first
This indicates that a more porous structure exists in RCP than in Ordinary Portland Cement (OPC), which increases the surface area of RCP

Summary

Introduction

The construction industry is encountering the challenge of incorporating sustainability into their production processes, either by searching for or incorporating new raw materials and products that are more environmental friendly and/or contributing towards the reduction of CO2 emissions into the atmosphere. The possibility of incorporating waste from industrial or agricultural activities in their production processes can help to achieve this goal [1]. Different pozzolans, such as fly ash, silica fume, metakaolin, and rice husk ash etc., are found to be viable cement alternatives [2,3,4,5]. These by-products have been found to significantly enhance the mechanical and durability properties of the resulting cementitious systems. Calcium carbide residue (CCR) is a by-product obtained from the acetylene gas (C2H2) production process, as shown in the following equation: CaC2 +2H2O → C2H2 + Ca(OH)2 [6]

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