Impact of Mixed-In Polyacrylic- and Phosphonate-Based Additives on Lime Mortar Microstructure.

Area of Science:

• Materials Science
• Civil Engineering
• Chemistry

Background:

• Porous building materials face weathering damage.
• Aminotris(methylene phosphonic acid) (ATMP) and poly(acrylic acid) sodium salt (PAA) show potential as protective additives.
• Lime-based mortars are susceptible to degradation.

Purpose of the Study:

• Investigate ATMP and PAA impact on lime-based mortar microstructure and mechanical properties.
• Assess influence of varying additive concentrations on CaCO3 crystallization, porosity, strength, and carbonation.
• Explore potential for enhanced material durability and performance.

Main Methods:

• Incorporation of ATMP and PAA at different concentrations into lime-based mortars.
• Analysis of CaCO3 crystallization morphology and phase stabilization (vaterite).
• Evaluation of porosity, pore connectivity, mechanical strength, and carbonation behavior.

Main Results:

• Additives induced nanostructured CaCO3 aggregates and stabilized vaterite, indicating non-classical crystallization via amorphous phases.
• Nanostructural changes enhanced mechanical performance through plastic deformation and intergranular bridging.
• Increased porosity and connectivity improved CO2 diffusion and strength development, though high concentrations negatively impacted performance due to air entrainment.

Conclusions:

• Optimized ATMP and PAA dosages significantly enhance lime-based mortar durability and mechanical properties.
• Additives facilitate biomimetic calcitic precipitation and nanostructural modifications.
• This offers a promising approach for durable material manufacturing in heritage restoration and sustainable construction.