DNN and XGBoost for modelling of strength of porous concrete with recycled aggregates

Because the production of aggregates for mortar and concrete is no longer sustainable, many attempts have been made to replace natural aggregates (NA) with recycled aggregates (RA) sourced from factories, recycling centers, and human activities such as construction and demolition works (C&D). This article reviews papers concerning mortars with fine RA from C&D debris, and from the by-products of the manufacturing and recycling processes of building materials. A four-step methodology based on searching, screening, clustering, and summarizing was proposed. The clustering variables were the type of aggregate, mix design parameters, tested properties, patents, and availability on the market. The number and the type of the clustering variables of each paper were analysed and compared. The results showed that the mortars were mainly characterized through their physical and mechanical properties, whereas few durability and thermal analyses were carried out. Moreover, few fine RA were sourced from the production waste of construction materials. Finally, there were no patents or products available on the market. The outcomes presented in this paper underlined the research trends that are useful to improve the knowledge on the suitability of fine RA from building-related processes in mortars.

Download Full-text

Strategies for a Circular Economy in the Construction and Demolition Sector: Identifying the Factors Affecting the Recommendation of Recycled Concrete

Sustainability ◽

10.3390/su13084113 ◽

2021 ◽

Vol 13 (8) ◽

pp. 4113

Author(s):

Valeria Superti ◽

Cynthia Houmani ◽

Ralph Hansmann ◽

Ivo Baur ◽

Claudia R. Binder

Keyword(s):

Circular Economy ◽

A Priori ◽

Recycled Concrete ◽

Recycled Aggregates ◽

Factors Affecting ◽

Structural Applications ◽

Adoption Of Innovation ◽

Decision Making Processes ◽

Behavioural Factors ◽

High Level

With increasing urbanisation, new approaches such as the Circular Economy (CE) are needed to reduce resource consumption. In Switzerland, Construction & Demolition (C&D) waste accounts for the largest portion of waste (84%). Beyond limiting the depletion of primary resources, implementing recycling strategies for C&D waste (such as using recycled aggregates to produce recycled concrete (RC)), can also decrease the amount of landfilled C&D waste. The use of RC still faces adoption barriers. In this research, we examined the factors driving the adoption of recycled products for a CE in the C&D sector by focusing on RC for structural applications. We developed a behavioural framework to understand the determinants of architects’ decisions to recommend RC. We collected and analysed survey data from 727 respondents. The analyses focused on architects’ a priori beliefs about RC, behavioural factors affecting their recommendations of RC, and project-specific contextual factors that might play a role in the recommendation of RC. Our results show that the factors that mainly facilitate the recommendation of RC by architects are: a senior position, a high level of RC knowledge and of the Minergie label, beliefs about the reduced environmental impact of RC, as well as favourable prescriptive social norms expressed by clients and other architects. We emphasise the importance of a holistic theoretical framework in approaching decision-making processes related to the adoption of innovation, and the importance of the agency of each involved actor for a transition towards a circular construction sector.

Download Full-text

Discrete Element Simulation Analysis of Biaxial Mechanical Properties of Concrete with Large-Size Recycled Aggregate

Sustainability ◽

10.3390/su13137498 ◽

2021 ◽

Vol 13 (13) ◽

pp. 7498

Author(s):

Tan Li ◽

Jianzhuang Xiao

Keyword(s):

Mechanical Properties ◽

Stress State ◽

Strain Curve ◽

Confining Pressure ◽

Recycled Concrete ◽

Recycled Aggregate Concrete ◽

Recycled Aggregate ◽

Recycled Aggregates ◽

Aggregate Model ◽

Large Size

Concrete made with large-size recycled aggregates is a new kind of recycled concrete, where the size of the recycled aggregate used is 25–80 mm, which is generally three times that of conventional aggregate. Thus, its composition and mechanical properties are different from that of conventional recycled concrete and can be applied in large-volume structures. In this study, recycled aggregate generated in two stages with randomly distributed gravels and mortar was used to replace the conventional recycled aggregate model, to observe the internal stress state and cracking of the large-size recycled aggregate. This paper also investigated the mechanical properties, such as the compressive strength, crack morphology, and stress–strain curve, of concrete with large-size recycled aggregates under different confining pressures and recycled aggregate incorporation ratios. Through this research, it was found that when compared with conventional concrete, under the confining pressure, the strength of large-size recycled aggregate concrete did not decrease significantly at the same stress state, moreover, the stiffness was increased. Confining pressure has a significant influence on the strength of large-size recycled aggregate cocrete.

Download Full-text

Mechanical strength and hydraulic properties of modified porous concrete mixtures

Journal of Physics Conference Series ◽

10.1088/1742-6596/1895/1/012027 ◽

2021 ◽

Vol 1895 (1) ◽

pp. 012027

Author(s):

Hussein J. Almansori ◽

Adnan Al-Sibahy ◽

Basim Al-Humeidawi

Keyword(s):

Mechanical Strength ◽

Hydraulic Properties ◽

Porous Concrete ◽

Concrete Mixtures

Download Full-text