Experimental development of low cement content and recycled construction and demolition waste aggregates concrete Keila Robalo a , Hugo Costa b,⇑ , Ricardo do Carmo b , Eduardo Júlio c a University of Cape Verde, Instituto Superior Técnico – Universidade de Lisboa, Department of Civil Engineering, Lisboa, Portugal b CERIS & ISEC-Polytechnic Institute of Coimbra, Department of Civil Engineering, Coimbra, Portugal c CERIS & Instituto Superior Técnico – Universidade de Lisboa, Department of Civil Engineering, Lisboa, Portugal highlights  Development of new sustainable concrete.  Development of low cement and recycled aggregates concrete, named LCRAC.  Formulation method for LCRAC with construction and demolition waste (CDW) aggregates.  Combining high compactness and reduced cement dosage with high volume of CDW aggregates.  Influence of high volume of CDW aggregates on mechanical properties of LCRAC.  Suitability of the predictions of concrete codes regarding LCRAC properties. article info Article history: Received 6 April 2020 Received in revised form 21 October 2020 Accepted 10 November 2020 Available online xxxx Keywords: Eco-efficient concrete Low cement content Recycled CDW aggregates LCRAC Mechanical performance abstract Innovative eco-efficient concrete was developed and characterized, to reduce the environmental impact related to construction and demolition waste, extraction of natural aggregates, and CO 2 emissions of Portland cement. Several concrete mixtures with low cement content and incorporating construction and demolition waste (CDW) recycled aggregates, herein named ‘‘low cement recycled aggregates con- crete” (LCRAC), were newly developed. Characterization tests were performed to minimize cement dosage and maximize the replacement of natural by CDW aggregates. An optimized matrix of low cement concrete was developed and high replacement volume rates of CDW aggregates (43–80%) were consid- ered, leading to different LCRAC, to evaluate their influence on concrete properties. The mechanical prop- erties of LCRAC are highly influenced by the aggregates composition and its replacement rate. A reduced and optimized cement dosage, of 175 kg/m 3 , allows producing sustainable LCRAC for structural applica- tions. The strength reduction of LCRAC is limited to only 30% when incorporating high volume of CDW, up to 60%, since the strength loss of CDW is balanced by the matrix high compactness and higher strength, resulting in equivalent strength of ordinary concrete formulation. Ó 2020 Elsevier Ltd. All rights reserved. 1. Introduction The worldwide consumption of concrete is about 10 billion tons per year and, although cement comprises only 10–15% in the weight of its constituents, it is nevertheless the main source of the environmental impact caused by the large scale of concrete use [1,2]. Portland cement is responsible for a high consumption of both raw materials and energy. Additionally, 80% of CO 2 emis- sions are originated by cement production [3,4]. On the other hand, the concrete industry consumes 9 billion tons of sand and rock, and 1 billion tons of water annually [1]. Considering that this consump- tion is expected to grow, up to a maximum of 18 billion tons per year by 2050 [5], a consequent increase of the greenhouse effect caused by the CO 2 emission into the atmosphere is also expected. So, it is essential to focus on the development of eco-efficient con- crete solutions to contribute to the decarbonization and to the sus- tainable growth of this sector. One of the main strategies to develop more eco-friendly concrete is to adopt practices that require less energy and natural materials, increasing the incorpora- tion of residues in concrete and / or using methods that improve the efficiency of the binder in concrete [6,7]. The recycling of waste produced not only by the construction industry itself but also by other industries can be used to replace https://doi.org/10.1016/j.conbuildmat.2020.121680 0950-0618/Ó 2020 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. E-mail address: hcosta@isec.pt (H. Costa). Construction and Building Materials xxx (xxxx) xxx Contents lists available at ScienceDirect Construction and Building Materials journal homepage: www.elsevier.com/locate/conbuildmat Please cite this article as: K. Robalo, H. Costa, R. do Carmo et al., Experimental development of low cement content and recycled construction and demo- lition waste aggregates concrete, Construction and Building Materials, https://doi.org/10.1016/j.conbuildmat.2020.121680