Microstructural and textural evolution of concrete made with recycled aggregate

• Main Author: Alani, Ahmed Anees
• Format: Conference Proceeding
• Language: English
• Subjects: Age hardening; Buildings; Calcium; Concrete aggregates; Fragments; Hydration; Microstructure; Porosity; Scrap; Silicates
• ISSN: 0094-243X; 1551-7616
• DOI: 10.1063/5.0190547

Fragments of destroyed buildings and structures have a wide range of applications due to its chemical and physical features; it has received attention from researchers as well as the industry community. In the present study, microstructure of concrete was investigated with the use of different types of aggregate, recycled aggregate from fragments of destroyed buildings and natural aggregate. Considering the contact zone of hydrated cement on aggregates, represented by the screening of concrete scrap crushing, it should be noted that even in the early stages of hardening at the age of 3 days, this contact zone is densely overgrown with hydration products and is barely visible in the electronic microscope images. This is explained by the fact that on the surface of the particles there are already crystals of calcium hydro silicates CSH, on which formations of calcium hydro silicates are formed. Having studied the microstructure of the samples with recycled aggregate at the ages of 3 days and 28 days, it can be argued that these compositions have the most perfect metal-crystalline microstructures, characterized by low porosity, it is noted that even small pores are gradually filled with hydration products, ensuring the formation dense cement stone. It has been proven that the aggregate from screenings of crushed concrete scrap has a high roughness, which determines the internal high adhesive ability and increases the strength of the products.