Abstract
Supplementary cementitious materials have been widely used to reduce the greenhouse gas emissions caused by ordinary Portland cement (OPC), including in the construction of road bases. In addition, the use of OPC in road base stabilization is inefficient due to its moisture sensitivity and lack of flexibility. Therefore, this study investigates the effect of hybrid alkali-activated materials (H-AAM) on flexibility and water prevention when used as binders while proposing a new and sustainable material. A cationic asphalt emulsion (CAE) was applied to increase this cementless material’s resistance to moisture damage and flexibility. The physical properties and structural formation of this H-AAM, consisting of fly ash, hydrated lime, and sodium hydroxide, were examined. The results revealed that the addition of CAE decreased the material’s mechanical strength due to its hindrance of pozzolanic reactions and alkali activations. This study revealed decreases in the cementitious product’s peak in the x-ray diffraction analysis (XRD) tests and the number of tetrahedrons detected in the Fourier transform infrared spectroscopy analysis (FTIR) tests. The scanning electron microscope (SEM) images showed some signs of asphalt films surrounding hybrid alkali-activated particles and even some unreacted FA particles, indicating incomplete chemical reactions in the study material’s matrix. However, the H-AAM was still able to meet the minimum road base strength requirement of 1.72 MPa. Furthermore, the toughness and flexibility of the H-AAM were enhanced by CAE. Notably, adding 10% and 20% CAE by weight to the hybrid alkali-activated binder produced a significant advantage in terms of water absorption, which can be explained by its influence on the material’s consolidation of its matrices, resulting in significant void reductions. Hence, the outcomes of this study might reveal an opportunity for developing a new stabilizing agent for road bases with water-prevention properties and flexibility that remains faithful to the green construction material concept.
Highlights
At present, ordinary Portland cement (OPC) replacements are being developed to reduce greenhouse gas emissions in the construction industry
The results indicate that the hybrid alkali-activated mortar’s initial and final setting time values were significantly delayed with an increase in cationic asphalt emulsion (CAE) content—as was true for the flow values
This study investigated the influence of CAE on the physical properties and structural formation of a hybrid alkali-activated materials (H-activated materials (AAMs))
Summary
Ordinary Portland cement (OPC) replacements are being developed to reduce greenhouse gas emissions in the construction industry. Pozzolanic materials with appropriate alkali activators can form the cementitious products calcium aluminosilicate hydrate gel (C-A-S-H), calcium silicate hydrate gel (CS-H), and sodium aluminosilicate hydrated product (N-A-S-H) [10,11,12,13,14]. These structural formations are similar to the hydration product resulting from mixing OPC and water [15]
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