An Experimental Study on Structural Concrete Containing Recycled Aggregates and Powder from Construction and Demolition Waste

Abstract

For complete utilization of construction and demolition (C&D) waste, an investigation of all size fractions of C&D waste generated during the recycling process should be conducted. In this work, the effects of three recycled concrete materials with different sizes (recycled coarse aggregate (RCA) with a size of 4.75–25 mm, recycled fine aggregate (RFA) of 0.15–4.75 mm, and recycled powder (RP) smaller than 0.15 mm) produced from concrete waste on the fresh and hardened mechanical properties of concrete were evaluated. The replacement ratios of natural coarse and fine aggregates by RCA and RFA were 30, 60, and 100%, and those of ordinary Portland cement for RP were 10, 20, and 30%. The results showed that the concrete properties deteriorated with increasing replacement ratio regardless of the type of recycled materials. The properties were reduced in the order of the use of RFA, RCA, and the simultaneous use of RCA and RFA. In addition, concrete with 30% RP showed lower mechanical strength than concrete with 100% RCA and 100% RFA. However, all concretes could be applicable for structural purposes under different environmental exposure conditions. In particular, concretes with 10% RP and 20% RP showed better cost-benefits compared to natural aggregate concrete with 100% ordinary Portland cement. These promising findings provide valuable initiatives for the effective and complete recycling of C&D waste.

Recycled Fine Aggregates from Mortar Debris and Red Clay Brick to Fabricate Masonry Mortars: Mechanical Analysis

“…Following the characterization of the fresh state mortars, a close affinity was observed between the mortar properties and the water/cement ratio; an increase in W/C ratio led to an increase in air content but a decrease in density of the fresh state mortars. This behavior followed the trend found by other researchers using several types of RFA in concrete [ 3 , 63 ] and mortar [ 37 , 45 , 64 ].…”

“…In recent years, the sustainable engineering of construction development has increased; therefore, several researchers have doubled their efforts toward projects where the mean objective is to analyze the feasibility of recycling construction and demolition waste (CDW) as new building materials, focusing on mechanical behavior, durability, and environmental impact [ 1 , 2 , 3 , 4 , 5 , 6 ]. One way these residues can be used is as partial substitutes for natural aggregates (NAs) in concrete and mortar mixes, such as recycled coarse aggregates (RCAs) and recycled fine aggregates (RFAs) [ 7 ].…”

Effect of Sustained Loading on the Direct Shear Behaviour of Recycled C&D Material–Geosynthetic Interfaces

“…Construction and demolition (C&D) was recognised as one of the priority sectors in this Circular Economy Package due to the vast amounts of C&D wastes generated across the European Union (over 35% of total waste generation), as well as their high potential for circularity. In fact, there has been increasing evidence that C&D materials can successfully be recycled and reused in a variety of civil engineering applications, such as concrete production [ 1 , 2 ], road and railway infrastructure [ 3 , 4 , 5 , 6 ], ground improvement works [ 7 ], geosynthetic-reinforced structures [ 5 , 8 , 9 , 10 , 11 , 12 ], among others. Taking into account that the construction sector is among the main contributors to the natural resource consumption (accounting for ≈50% of all extracted materials), the incorporation of recycled materials in the construction industry could save massive amounts of natural resources and play a notable role in achieving climate neutrality.…”

A Compensatory Approach for Enhancing the Strength and Durability of Green Concrete Composites (GCC) with Multiple Combinations of Recyclable Pozzolanic Materials (RPM)

“…Commonly used blending components include fly ash (FA), rice husk ash (RHA), granulated slag (GS), silica fume (SF), calcined clay (CC), and construction debris waste (CDW) powder [6][7][8][9][10][11][12]. There have been extensive studies reporting their suitability and application range as potential cementitious materials for green concrete [13][14][15][16][17][18][19][20]. Generally speaking, each of them vary in their micro-structural features, elemental compositions and therefore, inevitably, in their chemical reactivity with water.…”