Abstract
Abstract Red ceramics, due to the low compressive strength and high porosity, make it difficult to use it as an artificial aggregate in the production of mortars and concretes. However, since it has a silicon-rich composition, the ceramic material from blocks and tiles has been studied as a possible supplementary cementitious material in concrete and also as a raw material in alkali-activated binders. This paper aims to evaluate the content of calcium hydroxide (portlandite) fixed in the alkali activation reaction and the microstructure of red clay waste from construction and demolition waste (CDW) and hydrated lime mixtures, varying the atomic ratio between the silicon and the calcium. The results indicated that higher availability of lime is directly related to the content of hydrated compounds and its porosity. The increase in the silicon/calcium ratio resulted in a reduction of available lime content by 40% and an increase, in volume, of micropores by 7%.
Highlights
The concern with construction waste in Brazil started only in the late '80s (ANGULO et al, 2009) and it is estimated that the volume generated in the cities in 2018 reaches 0.585 kg.hab-1.day-1 and about 50% of solid waste generated nationwide is classified as construction and demolition waste (CDW) (ASSOCIAÇÃO..., 2019)
This paper aims to evaluate the calcium hydroxide consumption and the microstructure of the compositions formed by the red ceramic waste from mixed recycled aggregates and hydrated lime, varying the atomic relation between silicon and calcium
The red ceramics waste used in this research was obtained at the CDW recycling plant in the Brazilian city of Ponta Grossa
Summary
The concern with construction waste in Brazil started only in the late '80s (ANGULO et al, 2009) and it is estimated that the volume generated in the cities in 2018 reaches 0.585 kg.hab-1.day-1 and about 50% of solid waste generated nationwide is classified as construction and demolition waste (CDW) (ASSOCIAÇÃO..., 2019).The first CDW recycling plants in Brazil were installed by the city hall of São Paulo-SP (1991), LondrinaPR (1993) and Belo Horizonte-MG (1994) (MIRANDA; ANGULO; CARELI, 2009). In 2020, according to the Brazilian association for recycling of civil construction and demolition waste (ABRECON), there are 350 CDW recycling plants in Brazil. After processing by these plants, some of these residues are classified and marketed as mixed recycled aggregates, that is, they present in its composition ceramic materials mainly from bricks and tiles. These two components, associated with the excavation soil, are defined by "red fraction" and makeup to 48% of the total volume of the mixed recycled aggregates (ANGULO et al, 2009; SILVA et al, 2018). The mixed recycled aggregates classification in Brazil is defined by NBR 15116 (ABNT, 2004), stating that this material needs to present more than 90% of fragments from Portland cement composites, as opposed to the concrete recycled aggregates, composed of less than 90% of Portland cementbased materials
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
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 callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
