Abstract
This article demonstrates the possibility of producing alkali-activated materials (AAM) from a mixture of mechanically processed concrete, ceramic, masonry, and mortar wastes, as a sustainable alternative for recycling construction and demolition wastes (CDWs) under real conditions. The addition of 10% Portland cement allowed the materials to cure at room temperature (25 °C). CDW binder achieved a compressive strength of up to 43.9 MPa and it was classified as a general use and low heat of hydration cement according to ASTM C1157. The concrete produced with this cement and the crushed aggregates also from CDW reported a compressive strength of 33.9 MPa at 28 days of curing and it was possible to produce a high-class structural block with 26.1 MPa according to ASTM C90. These results are considered one option in making full use of CDWs as binder and aggregates, using alkaline activation technology thereby meeting the zero-waste objective within the concept of the circular economy.
Highlights
Construction and demolition wastes (CDWs) represent a severe environmental pollution problem in most countries, especially underdeveloped ones, due to their inadequate management and low rates of recycling or utilization
The results indicate that the presence of high NaOH+Sodium silicate (SS)/construction and demolition wastes (CDWs)+OPC (>0.35) ratios cause a decrease in compressive strength, both at 7 and 28 days of curing
A horizontal orientation of the contour lines is observed at 28 days of curing, as shown in Figure 6b, which demonstrates the non-significant effect of the NaOH/SS ratio on the compressive strength of the CDW binder
Summary
Construction and demolition wastes (CDWs) represent a severe environmental pollution problem in most countries, especially underdeveloped ones, due to their inadequate management and low rates of recycling or utilization. Global CDW generation is alarming, currently representing 25–30% of total solid waste worldwide [1], exceeding the quantity of 3 trillion tons per year [2] In response to this problem, the “2030 Agenda for Sustainable Development of the United Nations General Assembly”, approved in 2015 by the member countries of the UN, established the “Sustainable Cities” model. The production of recycled aggregates does not represent a solution for exploiting CDWs globally, mainly due to the low commercial competitiveness they possess when comparing their economic (non-environmental) cost with that of natural aggregates in many cities and countries This disadvantage is compounded by the lack of policies that control the indiscriminate exploitation of natural quarries, aimed at promoting the massive use of recycled aggregates as a replacement for natural aggregates. The search for recycling alternatives and/or applications with greater commercial value, which ensure the real use of CDWs, is a priority worldwide
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
