Workability and Mechanical Properties of Superplasticized Microfine Cement Grouts

Area of Science:

• Civil Engineering
• Materials Science
• Construction Materials

Background:

• Superplasticizers (SP) are vital for enhancing the groutability of microfine cement (MC) in civil engineering.
• The combined effects of cement type, SP type, SP dosage, and water-solid ratio (W/S) on the engineering performance of MC are not fully understood.

Purpose of the Study:

• To systematically evaluate the workability and mechanical properties of superplasticized microfine cement grouts (SMCG).
• To investigate the influence of different cement types and SP types on grout performance.
• To determine optimal formulation parameters for SMCG.

Main Methods:

• Investigated three different microfine cements (CEM I, CEM II/B-M, CEM III/B) and four SPs (naphthalene-based, melamine-based, two polycarboxylate-based).
• Evaluated rheological behavior (mini-slump, flowability, viscosity), fresh-state properties (bleeding, setting time), mechanical performance (strength, shrinkage), and microstructure.
• Utilized a new static viscosity method to assess viscoelasticity.

Main Results:

• Polycarboxylate-based (PCE) SPs showed superior dispersion effects on rheological behavior compared to melamine-based (M) and naphthalene-based (N) SPs.
• Excessive SP content led to instability, prolonged setting times, and oversaturation.
• SP addition can improve flexural strength (FS) and bending toughness.

Conclusions:

• Optimal W/S ratio is recommended to be within 1.5 for balancing workability and mechanical performance.
• Recommended optimal SP dosages: N (1.5-2.0%), M (1.2-1.5%), and PCE (0.9-1.2%).
• Formulation parameters significantly impact the engineering performance of superplasticized microfine cement grouts.