High-strength lightweight blocks prepared from the by-product of aluminium removed from fly ash

A large amount of powder by-product is generated when Al2O3 is extracted from fly ash. The purpose of this study is to investigate the properties of the powder and find an effective method to reuse it. XRF, XRD, and SEM were used to analysis its compositions and microstructures. The powder was then compressed at the pressure of from 20 to 100 MPa. Results show that the powder was disordered calcium silicate hydrate with an average Ca/Si molar ratio of 1.08. It becomes hardened blocks by compressing. The bulk density of the hardened blocks is between 500 and 800 kg m-3 corresponding to the pressure of 20 to 60 MPa. Their flexible strength is from 1.60 to 5.35 MPa, and compressive strength from 8.50 to 30.50 MPa. The blocks can be recycled by repeating the procedure of crushing blocks, grinding them into powder, and compressing the powder into hardened blocks. This powder can be sustainably reused to prepare lightweight blocks with high strength

Influence of inorganic admixtures on the 11 angstrom-tobermorite formation prepared from steel slags: XRD and FTIR analysis

Calcium silicate hydrate is synthesized from steel slag by adding lime and quartz by dynamic hydrothermal method at 185 degrees C. The products mainly consist of disordered calcium silicate hydrate, but more crystallized phase such as 11 angstrom-tobermorite forms for the presence of inorganic admixtures. The formation of tobermorite is affected by the types of ions according to XRD and FTIR results. Adding 2% crystallized tobermorite is beneficial to form the ordered structure; alkali cations and SO42- anions are effective accelerators; Al3+ plays a role of stabilization during the reaction. The products also vary with the initial alkalinities of steel slag

Influence of Hydrothermal Synthesis Conditions on the Formation of Calcium Silicate Hydrates: from Amorphous to Crystalline Phases

Hydrothermal treatment has been widely applied in the synthesis of well crystalline calcium silicate hydrate (CSH), such as tobermorite and xonotlite. However, both morphology and crystallinity of CSH are greatly affected by the conditions of hydrothermal treatment including siliceous materials, temperature increase rate and isothermal periods. In this study, the influence of hydrothermal conditions on the growth of nano-crystalline CSH was investigated based on XRD analysis. Results showed that siliceous materials with amorphous nature (i e, nano silica powder) are beneficial to synthesize pure amorphous CSH, while the use of more crystallized siliceous materials (i e, diatomite and quartz powder) leads to producing crystalline CSH. Results also indicate that the formation of tobermorite and xonotlite is greatly affected by the temperature rise rate during hydrothermal treatment

Additional file 1 of Using a new human milk fortifier to optimize human milk feeding among very preterm and/or very low birth weight infants: a multicenter study in China

Supplementary Material