Hongyu Shao

Non-steady state migration of chloride ions in cement pastes at early age

This paper proposes preliminary work to study the diffusion and migration of chloride ions in cement pastes at early age. The non-steady state ion migration coefficients of cement pastes are evaluated from three aspects: (1) electrical rapid ion migration test; (2) non-contact impedance measurement (NCIM) based on a fractal model; and (3) a corresponding simulation of an “I” shape fractal network. The experimental results from electrical rapid ion migration tests and NCIM have good agreement. The influences of water to cement ratio, curing hydration age and addition of mineral admixtures on the performance of ion diffusion/migration in cement pastes are investigated.

CONTINUOUS MICROSTRUCTURAL CORRELATION OF SLAG/SUPERPLASTICIZER CEMENT PASTES BY HEAT AND IMPEDANCE METHODS VIA FRACTAL ANALYSIS

This paper presents a preliminary work to evaluate the influence of slag and superplasticizer on the early-age hydration of cement pastes by an innovative non-contact impedance measurement, heat evolution method, compressive strength and setting time tests. Besides, the cumulative pore volume obtained from modulus and phase of impedance in different hydration sections is taken to continuously correlate the cumulative heat releasing of cement pastes via the fractal analysis. Retarded phenomena and mechanism of hydration in cement pastes incorporated with slag and superplasticizer are studied, respectively. It is found that the compressive strength and setting time have a good linear relation with the slag amount in blended cement pastes.