Abstract
Metropolitan construction and demolition waste (CDW) is currently an important source of recycled materials that, despite having completed their useful life cycle, can be reincorporated into the circular economy process (CEP); however, the recycling process is very selective, and waste material is not always fully satisfactory due to the intrinsic nature of the waste. This work aims to demonstrate and establish how to increase the effectiveness of the construction and demolition waste in more resistant mortars, by mixing it with zeolitised cinerite tuff (ZCT) at varying normalised proportions. To attain the objectives of this research, a series of tests were done: First, a chemical, physical and mineralogical characterisation of the CDW and the ZCT through XRF, XRD, SEM and granulometric methods. Second, a technological test was made to determine the mechanical strength at 7, 28 and 90 days of specimens made with Portland cement (PC) and mixtures of PC/CDW, PC/ZCT, and PC/CDW-ZCT. The results obtained through the characterisation methods showed that the sample of construction and demolition waste consisted of the main phase made of portlandite and tobermorite, and by a secondary phase consisting of quartz, ettringite and calcite; whereas the ZCT has a main phase of mordenite and a secondary phase of smectite (montmorillonite), amorphous materials consisting of devitrified volcanic glass, quartz and plagioclase. Mechanical strength tests established that specimens made with PC/CDW mixtures have very discreet compressive strength values up to 44 MPa at 90 days, whereas specimens made with PC/ZCT mixtures achieved a remarkably high mechanical strength consisting of 68.5 MPa. However, the most interesting conclusion in this research is the good result obtained in mechanical strength of the specimens made up of mixtures of PC/CDW-ZCT, which increased from 52.5 to 62 MPa at 90 days of curing; this fact establishes the positive influence of ZCT on waste in the mortar mixtures, which permits the authors to establish that the objective of the work has been fulfilled. Finally, it can be argued that the results obtained in this research could contribute to more effective use of construction and demolition waste in metropolitan areas.
Highlights
IntroductionAn environmental emergency is pressing us today
The idea of the possible depletion of resources in the short term has awakened the need to look for new alternatives, such as the reuse of materials from old buildings, which could be a definitive alternative, since large volumes of construction and demolition waste are accumulated every year in the great metropolises of the world, whose degradation by weathering agents seriously damages soils, aquifers, air quality, among others
Among the main objectives of this work is to monitor the mechanical behaviour of a series of specimens designed with different proportions of mixtures, in which the contents of construction and demolition waste (CDW) vary in relation to natural aggregate (NA), until obtaining a final mixture that totally replaces
Summary
An environmental emergency is pressing us today. The growing geopolitical conflicts of the world’s major economic blocs are rooted in the availability and management of natural resources. The idea of the possible depletion of resources in the short term has awakened the need to look for new alternatives, such as the reuse of materials from old buildings, which could be a definitive alternative, since large volumes of construction and demolition waste are accumulated every year in the great metropolises of the world, whose degradation by weathering agents seriously damages soils, aquifers, air quality, among others. Pacheco-Torgal et al [1] mention that the European construction sector produces about 890 million tonnes of waste per year, and point out that the amended Waste
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