Zhitao Chen

Gas Generation from Incinerator Bottom Ash: Potential Aerating Agent for Lightweight Concrete Production

AbstractIncinerator bottom ash (IBA) has great potential to be utilized for civil engineering applications. This paper is to investigate the characteristic of gas generation from IBA and to study the potential of IBA as an aerating agent. Results show the aeration capacity of IBA used in this study is approximately 1% that of pure aluminum powder by mass. Finer particles, higher alkali molarity, and higher reaction temperature encourage the reaction and more gas is generated per gram of IBA. Type of alkaline solution does not seem to be an important factor for gas generation from IBA. Several exemplary lightweight mortars were produced by incorporating IBA as an aerating agent. It is highly plausible IBA can be used as an aerating agent to replace pure aluminum powder in the production of aerated concrete.

High Strength Lightweight Strain-Hardening Cementitious Composite Incorporating Cenosphere

High strength lightweight concrete was originally designed for potential structural applications. However, the brittle nature and higher permeability became the main drawbacks for further broad application. In this case, it is imperative to develop a special type of high strength strain hardening lightweight cementitious composite, offering higher ductility, lower permeability and considerable weight saving. Engineered cementitious composite (ECC) is a class of high performance fiber reinforced composite characterized by strain hardening behavior and tight crack width. In this study, the low density of below 1500 kg/m was achieve by introduce lightweight fine aggregates of cenosphere obtained from coalfired power station to fully replace silica sand generally used in ECC preparation. Binary and ternary binder systems (cement, silica fume and slag) were employed to tailor the matrix properties for obtaining higher strength of more than 50 MPa and lower permeability. Polymeric fibers having a good compatibility with matrix were used to implement strain hardening behavior and higher ductility. The permeability and thermal conductivity tests were conducted to evaluate the applicable performance of resulting lightweight cementitious composite. The correlation between mechanical, physical and thermal properties was build up to reveal the effect of cenosphere on the performances of high strength lightweight strain hardening cementitious composite. The single fiber pull out test and matrix fracture toughness test were conducted to reveal the micromechanical mechanism of strain hardening behavior of high strength lightweight composites.