5.1.3. CAC + Environmental Science

A search with the keywords, calcium aluminate cement and Environmental science (CAC + Environmental science) in the Scopus database yielded 5 results. The number of documents produced per year is presented in Figure 8c. This reveals almost no production in the last 20 years.

L. Xu, et al. [64] investigated setting times, mechanical strength and drying shrinkage ratio of mixed OPC and CAC systems (less than 25%). They found that with CAC, the set times of combined systems are shortened; the compressive strength first increases slightly (peaks with 6% calcium aluminate cement) and then decreases significantly. T.T. Akiti Jr, et al. [65,66] developed a calcium-based sorbent to desulfurize the hot carbon gas, this led to the development of a spherical granule-like material, which has a limestone-based core enclosed in a strong support layer. Strong granules are prepared by incorporating some CAC into the core and a larger amount into the shell, along with the limestone.

The granules are prepared by a two-step granulation method, followed by steam curing and heat treatment. It was found that the granules are capable of absorbing relatively large amounts of hydrogen sulfidic at high temperature (e.g., 1150–1200 K) that can be regenerated by a cyclical oxidation and reduction process.

Secondary aluminum dross (SAD) is a dangerous pollutant as well as a valuable resource. About 95% SAD is disposed by stockpiling on the spot due to its complex composition and technical limitations, causing severe ecological damage and public health threat [67]. Mingzhuang et al. [67] developed a new green process for the preparation of ultrafine and high-whiteness Al(OH)<sup>3</sup> from SAD. This phase can then be used as a high-strength cementitious material by mixing it with CAC.
