.png){kind=icon}
.png){kind=icon}
Return
Effect of Mixing Sequence and Curing Method on Alkali-Activated Mortar Properties
.png){kind=icon}
OA
AI
D
I
N
M
DOI：10.3390/buildings16163200.png)
.png){kind=icon}
Original request for help.png){kind=icon}
Share.png){kind=icon}
Save
Abstract
En 中文
In this study, brick plant waste was used to produce alkali-activated mortars. Four mixtures with identical compositions but different mixing sequences and curing methods were prepared. Two were conventionally produced using a pre-cooled 10 M potassium hydroxide (KOH) solution and sodium silicate (Na2SiO3), with one cured at ambient conditions and the other at an elevated temperature. The remaining two used modified mixing sequences to utilize internally generated heat for curing (direct KOH powder addition and addition of KOH dissolved in water immediately before mixing). The influence of mixing sequence and curing method on mechanical properties and high-temperature performance was evaluated after exposure to 600 °C through residual flexural and compressive strengths, mass loss, and visual examination of specimen cross-sections. The two best-performing mortars were further characterized by Fourier-transform infrared spectroscopy (FT-IR) and field-emission scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (FE-SEM-EDS), while the mixture combining favorable high-temperature performance with simple preparation was additionally analyzed for thermal conductivity and specific heat capacity. The conventionally prepared, elevated-temperature-cured mixture exhibited the lowest room-temperature flexural and compressive strengths (2.7 and 12.9 MPa, respectively) but the best high-temperature performance, with flexural and compressive strength increases of 14.8% and 10.9%, respectively, after exposure to high temperature. Visual assessment may suggest some degree of structural densification in this mixture and in the mixture prepared by direct addition of KOH powder to the dry components, whereas the other two mixtures may exhibit signs of partial weakening in the interfacial transition zone (ITZ). Among the internally cured mixtures, direct KOH powder addition produced slightly better room- and high-temperature performance than adding KOH dissolved in water immediately before mixing. FT-IR and FE-SEM-EDS confirmed the formation of potassium and sodium aluminosilicate hydrate, (K,N)-A-S-H, gel in the conventionally prepared, elevated-temperature-cured mixture and the mixture with direct KOH powder addition. The nearly unchanged compressive strength of the KOH-powder-based mixture was associated with a high retention of thermal conductivity (93%) and specific heat capacity (80%) after high-temperature exposure.
Keywords:
alkali-activated mortar
mixing sequence
curing method
high-temperature performance
FT-IR
FE-SEM-EDS analysis
thermal properties
Journal
IF:
3.1
Papers:
1.7W
Citations:
2.5W
Organization
Cited Papers