Superplasticizer | EPFL Graph Search

Superplasticizers (SPs), also known as high range water reducers, are additives used for making high-strength concrete or to place self-compacting concrete. Plasticizers are chemical compounds enabling the production of concrete with approximately 15% less water content. Superplasticizers allow reduction in water content by 30% or more. These additives are employed at the level of a few weight percent. Plasticizers and superplasticizers also retard the setting and hardening of concrete. According to their dispersing functionality and action mode, one distinguishes two classes of superplasticizers: Ionic interactions (electrostatic repulsion): lignosulfonates (first generation of ancient water reducers), sulfonated synthetic polymers (naphthalene, or melamine, formaldehyde condensates) (second generation), and; Steric effects: Polycarboxylates-ether (PCE) synthetic polymers bearing lateral chains (third generation). Superplasticizers are used when well-dispersed cement particle suspensions are required to improve the flow characteristics (rheology) of concrete. Their addition allows to decrease the water-to-cement ratio of concrete or mortar without negatively affecting the workability of the mixture. It enables the production of self-consolidating concrete and high-performance concrete. The water–cement ratio is the main factor determining the concrete strength and its durability. Superplasticizers greatly improve the fluidity and the rheology of fresh concrete. The concrete strength increases when the water-to-cement ratio decreases because avoiding to add water in excess only for maintaining a better workability of fresh concrete results in a lower porosity of the hardened concrete, and so to a better resistance to compression. The addition of SP in the truck during transit is a fairly modern development within the industry. Admixtures added in transit through automated slump management system, allow to maintain fresh concrete slump until discharge without reducing concrete quality.

Rheological Properties of Ionically Crosslinked Viscoelastic 2D Films vs. Corresponding 3D Bulk Hydrogels

Esther Amstad, Gaia De Angelis

Ionically crosslinked hydrogels containing metal coordination motifs have piqued the interest of researchers in recent decades due to their self-healing and adhesive properties. In particular, catechol-functionalized bulk hydrogels have received a lot of a ...

AMER CHEMICAL SOC2023

Reuse of concrete components in new construction projects: Critical review of 77 circular precedents

Corentin Jean Dominique Fivet, Maléna Bastien Masse, Célia Marine Küpfer

Extracting pieces of concrete from obsolete buildings and reusing them, as is, in new assemblies is today rarely considered a strategy for improving the sustainability of the construction sector. By delaying the crushing of concrete into aggregates and avo ...

2023

SARS-CoV-2 Inhibition by Sulfonated Compounds

Francesco Stellacci, Matteo Gasbarri, Valeria Cagno

Severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2) depends on angiotensin converting enzyme 2 (ACE2) for cellular entry, but it might also rely on attachment receptors such as heparan sulfates. Several groups have recently demonstrated a ...

2020