Zaid Ghouleh

Reaction Products in Carbonation-Cured Lightweight Concrete

The effect of early-age carbonation curing on the microstructure and properties of lightweight concrete with expanded slag aggregates was examined. Carbonation was performed on concretes either immediately after casting or after 18-h air curing. Their corresponding carbon uptake was 8 and 23%, respectively, based on cement content. A process involving initial air curing, carbonation curing, water compensation, and subsequent hydration was developed to maximize the degree of carbonation and hydration. Reaction products of carbonation-cured concretes at early and late age were characterized by using thermogravimetrical (TG) analysis, X-ray diffraction analysis, and scanning electron microscopy. Although the presence of calcium carbonates was evident, the microstructure was nevertheless typical of amorphous. It was believed that early carbonation of concrete consumed calcium hydroxide, calcium silicate hydrates, and anhydrous calcium silicates while producing calcium carbonates of different polymorphs and amorphous calcium silicate hydrocarbonates.

Processing of Municipal Solid Waste (MSW) Fly Ash into an Environmentally Stable and Safe Material

The purpose of this research was to design a processing route for the conversion of hazardous Municipal Solid Waste (MSW) fly ash into a glass-ceramic material, stable and safe for further industrial, structural, or ornamental applications. The process firstly consists in the transformation of a hazardous MDW fly ash into a vitrous material. Thermal analyses information was used to design the controlled heat treatment that further transformed this vitrous material into an environmentally safe composite. The final product obtained was a glass-ceramic material with randomly oriented crystals embedded in its residual amorphous matrix. The crystalline phases were identified as Nepheline and Diopside. CLSM (Confocal Laser Scanning Microscopy) was used for real-time in-situ observation of the microstructure under simulated heat treatment conditions.