Improving the Performance of Mortars Made from Recycled Aggregates by the Addition of Zeolitised Cineritic Tuff

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.

Improvement of the Mechanical Properties of Mortars Manufactured with Partial Substitution of Portland Cement by Kaolinitic Clays

“…The calculation of the Resistant Activity Index (RAI) has once again permitted the recording of the criteria established in this work regarding the influence of the chemical constitution, porosity, specific surface, and pozzolanic activity of the samples studied and their increase once they have been subjected to high normalized temperatures. The papers of Presa et al [55], Martín et al [56], and Rosado et al [57] describe similar conclusions that support the arguments discussed in this research.…”

Mineral, Chemical and Technical Characterization of Altered Pyroxenic Andesites from Southeastern Spain for Use as Eco-Efficient Natural Materials

“…It seems that the substitution of Portland cement at both 25% and 30% does not significantly affect the development in mechanical strength of this type of specimen. Martín et al [36] have opted to increase in a controlled manner the replacement of cement with natural aggregates above 70% with satisfactory results.…”