Browsing by Autor "Romildo Dias Tolêdo Filho"

Now showing 1 - 3 of 3

Evaluating the Use of Recycled Brick Powder as a Partial Replacement for Portland Cement in Concrete
(National University of Colombia, 2024) Joaquín Humberto Aquino Rocha; Boris Marcelo Morales Ruiz; Romildo Dias Tolêdo Filho
Portland cement is one of the most used construction materials. However, its production represents between 5 and 7% of the total CO2 emissions. On the other hand, during construction and demolition activities, different wastes are produced, including recycled brick powder (RBP), whose potential as a supplementary cementitious material (SCM) has been demonstrated in the literature. This research aims to evaluate RBP as a partial replacement for Portland cement in concrete. 5 to 10% of Portland cement was replaced with RBP in two strength designs (20 and 25 MPa) in order to propose concretes that meet the requirements for use in construction. Tests involving slump, compressive strength, tensile strength by diametrical compression, absorption, density, and void content were performed. The results show that a 5% RBP replacement does not affect workability in concrete mixes, as it maintains their mechanical resistance and slightly improves their physical properties. On the other hand, 10% RBP replacements adversely affect workability and reduce tensile strength. These results are attributed to pozzolanic activity and the physical effect caused by RBP, whose performance may be improved by reducing RBP particles and increasing their specific surface area (SSA). Using RBP as a replacement for Portland cement to produce concrete is a viable alternative with a sustainable approach.
Physical-mechanical assessment to mortars including recycled concrete powder and metakaolin
(Elsevier BV, 2024) Joaquín Humberto Aquino Rocha; Romildo Dias Tolêdo Filho
This study aims to evaluate the mechanical and physical properties of mortars incorporating recycled concrete powder (RCP) and metakaolin (MK), a widely utilized supplementary cementitious material (SCM). The mortars were partially replaced with 30 % of either MK or RCP sourced from three distinct sources: construction, demolition, and laboratory. Various parameters, including workability, compressive strength, splitting tensile strength, elastic modulus, water absorption, capillary water absorption, density, void index, and microstructural characteristics of the mortar, were assessed. The findings indicate that the workability of mortars generally decreased due to the morphology and specific surface area of the particle mixtures of RCP and MK. The incorporation of RCP negatively affected the mechanical properties of the mortar. Conversely, mixtures of MK and RCP were observed to maintain or even enhance the mechanical properties of the mortars across all evaluated time intervals (7, 28, and 91 days). In terms of physical properties, the combination of RCP and MK generally led to a reduction in water absorption and capillary water absorption, as well as a decrease in density and void index. Additionally, the use of MK in combination with RCP resulted in a reduction in the amount of cement required (kg·m −3 ·MPa −1 ) compared to the reference mix, demonstrating that this alternative approach is not only technically viable but also sustainable.
Sustainable alternatives to CO2 reduction in the cement industry: A short review
(Elsevier BV, 2022) Joaquín Humberto Aquino Rocha; Romildo Dias Tolêdo Filho; Nahúm Gamalier Cayo Chileno