Effect of carboxylic and hydroxycarboxylic acids on cement hydration: experimental and molecular modeling study

Retardation of Portland Cement Hydration with Photosynthetic Algal Biomass

“…Of the identified functional groups, the carboxyl (−COOH) and hydroxyl (−OH) groups have been commonly found to retard cement hydration. , The addition of glycolic acid that possesses carboxyl and hydroxyl groups has been shown to substantially retard the hydration of cement. For instance, addition of 0.2% glycolic acid extended the induction period of cement paste from 1.5 to 8 h (w/c = 0.35) …”

“…Mechanistically, the carboxyl and hydroxyl groups retard cement hydration via adsorption onto minerals found in cement, especially hydroxylated C 3 S . For instance, these functional groups from glycolic acid or calcium glycolate are hypothesized to interact with surrounding water molecules and form hydrogen bonds, which form a stable hydrogen bond network covering the surfaces of cement particles.…”

“…18,19 To the authors' knowledge, no studies have yet explored the potential for untreated algae to accelerate or retard the hydration of portland cement. Algae possess functional groups such as −COOH that exhibit potential for retarding the kinetics of cement hydration, 20,21 unlike other types of biomass, including cellulosics and lignins, that exhibit fewer −COOH groups. 22 While some alginate-based biopolymers have exhibited retardation effects on portland cement hydration, 16 the biopolymers also accelerated the hydration of calcium alumina cements, because the −COOH groups adsorb calcium ions and serve as nucleation sites for the formation of calcium aluminate hydrate phases.…”

Molecular dynamics simulation of the interaction of uranium (VI) with the C–S–H phase of cement in the presence of gluconate

“…Consequently, the molecular mechanisms of their interaction with all components of the waste storage system should be systematically studied, quantitatively described, and understood in detail. Several recent studies shed light upon the behavior of organics in cementitious materials (Nalet and Nonat, 2016;Chaudhari et al, 2017;Orozco et al, 2017) and their effect on the mobility of radionuclides in cement (Pointeau et al, 2006(Pointeau et al, , 2008García et al, 2018). However, to our knowledge, the molecular mechanisms controlling the behavior of the ternary systems (C-S-H/radionuclide/organic) have not yet been investigated.…”

A consideration on the one-part mixing method of alkali-activated material: problems of sodium silicate solubility and quick setting

“…Some researchers have concluded that sucrose retards the setting time and improves the microstructure of OPC concrete [ 40 , 41 ]. Besides sucrose, some other kinds of retarder are also available, such as lignosulfonic acid, hydroxycarboxylic acids, and their salts, and carbohydrates, such as glucose [ 42 ]. But using sucrose as a retarder has the advantage of sustainability and availability.…”