Development of Alkali Activated Inorganic Foams Based on Construction and Demolition Wastes for Thermal Insulation Applications

Abstract

Nowadays, the construction industry is challenged not only by increasingly strict environmental regulations, but also by a shortage of raw materials and additives. It is critical to find new sources with which the circular economy and zero waste approach can be achieved. Promising candidates are alkali activated cements (AAC), which offer the potential to convert industrial wastes into higher added value products. The aim of the present research is to develop waste-based AAC foams with thermal insulation properties. During the experiments, pozzolanic materials (blast furnace slag, fly ash, and metakaolin) and waste concrete powder were used to produce first dense and then foamed structural materials. The effects of the concrete fractions, the relative proportions of each fraction, the liquid/solid ratio, and the amount of foaming agents on the physical properties were investigated. A correlation between macroscopic properties (strength, porosity, and thermal conductivity) and micro/macro structure was examined. It was found that concrete waste itself is suitable for the production of AACs, but when combined with other aluminosilicate source, the strength can be increased from 10 MPa up to 47 MPa. The thermal conductivity (0.049 W/mK) of the produced non-flammable foams is comparable to commercially available insulating materials.

Analysis of the Performance of Recycled Insulation Concrete and Optimal Mix Ratio Design Based on Orthogonal Testing

“…China’s environmental pollution and energy shortages have become increasingly conspicuous due to the country’s burgeoning economy and construction industry. On the one hand, the frequent remodeling, tearing down, and new construction of buildings have produced a large volume of construction solid waste [ 1 , 2 , 3 ]. With the current supply of sand, stone, and other natural resources, which is relatively tight, the use of construction solid waste to prepare recycled concrete can achieve partial recycling of construction solid waste [ 4 , 5 , 6 ].…”