Banca de QUALIFICAÇÃO: EVERTON DE LIMA DE ANDRADE

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : EVERTON DE LIMA DE ANDRADE
DATE: 22/05/2026
TIME: 08:30
LOCAL: Remoto
TITLE:

EVALUATION OF ACCELERATORS IN LC3-BASED CEMENTITIOUS MORTARS FOR 3D PRINTING

KEY WORDS:

3D printing; Limestone calcined clay cement; Hardening accelerators; Setting accelerators.

PAGES: 122
BIG AREA: Engenharias
AREA: Engenharia de Materiais e Metalúrgica
SUBÁREA: Materiais Não-Metálicos
SPECIALTY: Materiais Conjugados Não-Metálicos
SUMMARY:

The search for sustainable alternatives in civil construction highlights limestone cement with calcined clay (LC³) as a promising solution, thanks to its reduction in CO₂ emissions. However, its low initial strength limits its use in innovative technologies, such as 3D printing, which requires materials with fluidity and rapid strength acquisition. To overcome this limitation, the use of setting accelerators has proven effective, optimizing the initial properties of LC³ mortars and enabling their application in sustainable and efficient construction systems. This study evaluates the influence of three chemical accelerators—potassium sulfate (K2SO4), calcium chloride (CaCl2) and sodium hydroxide (NaOH)—at two dosage levels (1.5% and 3.0% by binder mass) on the performance of limestone calcined clay cement (LC3) mortars for 3D printing applications. CaCl2 and NaOH significantly accelerated setting times, with reductions of up to 66% and 57% in initial setting time, respectively, enhancing early-age workability and buildability. CaCl2 notably improved early mechanical properties, increasing tensile strength from 0 to ~1.8 MPa and compressive strength by over 3000% after 6 h, while NaOH primarily enhanced fresh-state stiffness and load-bearing capacity with moderate strength gains at later ages. In contrast, K2SO4 functioned mainly as a hardening accelerator, increasing 1-day tensile and compressive strengths by 82% and 144%, respectively, without substantially affecting setting times or fresh-state properties. Microstructural characterization revealed that CaCl2 and NaOH accelerate hydration kinetics but may compromise long-term durability due to incomplete phase development and heterogeneous pore structures, whereas K2SO4 promotes stable ettringite formation and matrix integrity. These findings provide critical insights for selecting accelerator types and dosages to optimize the rheology, buildability, and mechanical performance of 3D-printed LC3 mortars in sustainable construction.

COMMITTEE MEMBERS:
Presidente - 1298936 - ANTONIO EDUARDO MARTINELLI
Externa ao Programa - 2621720 - ANA CECILIA VIEIRA DA NOBREGA - UFRNExterno ao Programa - 2351540 - PAULO ALYSSON BRILHANTE FAHEINA DE SOUZA - UFRN