Abstract
This paper investigates the mechanical and shrinkage behaviour of concrete with recycled cement (RC) thermoactivated from waste cement paste and waste concrete. Overall, compared to ordinary Portland cement (OPC), for the same water/binder ratio, the mechanical strength and ultrasonic pulse velocity were not significantly influenced by the incorporation of RC. The elasticity modulus decreased with the addition of RC and the shrinkage tended to increase at high RC content. The incorporation of up to 15% RC allowed the production of workable concrete with identical shrinkage and similar to higher mechanical strength than concrete with only OPC. RC proved to be a very promising more eco-efficient supplementary cementitious material.
Highlights
The growing concern with the impact of the construction industry on the environment has prompted investigation works on concrete recycling to reduce the consumption of natural resources and the emissions of greenhouse gas, as well as to repurpose construction and demolition waste [1,2].For various decades, concrete recycling studies have mainly addressed its use as coarse and fine aggregates as well as low-activity filler additions [3]
In this still relatively unexplored domain, studies have mostly focused on the microstructure and rehydration behaviour of recycled cement (RC) [5,6,7,8,9,10], as well as the mechanical characterisation of cement pastes and mortars produced with this binder [11,12,13,14,15,16,17,18]
This paper aims at characterising the mechanical and shrinkage behaviour of concrete produced with various replacement percentages of ordinary Portland cement (OPC) with RC, for distinct w/b
Summary
The growing concern with the impact of the construction industry on the environment has prompted investigation works on concrete recycling to reduce the consumption of natural resources and the emissions of greenhouse gas, as well as to repurpose construction and demolition waste [1,2].For various decades, concrete recycling studies have mainly addressed its use as coarse and fine aggregates as well as low-activity filler additions [3]. The attention has shifted towards the production of recycled cement (RC) with rehydration capacity through thermal activation [1,4]. In this still relatively unexplored domain, studies have mostly focused on the microstructure and rehydration behaviour of RC [5,6,7,8,9,10], as well as the mechanical characterisation of cement pastes and mortars produced with this binder [11,12,13,14,15,16,17,18]. Real et al [9] recounted similar flexural and compressive strength up to 3 days of pastes with RC treated at 600–700 ◦ C and reference ordinary Portland cement (OPC)
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