Zhang, Chenchen, et al. Case Studies in Construction Materials 21 (2024): e03709.
The performance of cement-based materials is critically influenced by their microstructure, which can be modified using chemical additives. Ion chelators are one such class of additives that can alter the hydration process. This study investigated the effects of four ion chelating agents on the mechanical properties, transport properties, and microstructure of cementitious composites. The tested ion chelating agents included pentasodium diethylenetriamine pentaacetate (5Na-DTPA), tetrasodium ethylenediaminetetraacetate (4Na-EDTA), sodium hexametaphosphate (SHMP) and tetrasodium glutamate diacetate (4Na-GLDA), with a dosage of 1% of the cement mass.
Key Findings:
· Early-Age Performance (3 & 7 days): At 3 days, all four chelators reduced early compressive strength versus the control (S0). For the four chelator-containing specimens labelled SD, SE, SS and SG, the reported reductions in 3-day compressive strength relative to S0 were 26.42% (SD), 17.38% (SE), 43.02% (SS) and 21.73% (SG). MIP and SEM analysis confirmed an increase in porosity and a looser microstructure at this stage due to the chelator's interaction with calcium ions.
· Long-Term Performance (28 & 56 days): By 28 and 56 days, the presence of ion chelators improved compressive strength, transport properties and pore structure relative to the early-age trend; the later-stage improvements were most pronounced at 56 days. When comparing the four chelators' net improvements at 28 and 56 days, the reported order from smallest to largest enhancement was: 5Na-DTPA → 4Na-GLDA → 4Na-EDTA → SHMP
Yang, Yingying, et al. Advanced Energy Materials 14.23 (2024): 2400416.