Novel Slow-Release Defoamers for Concrete Using Porous Nanoparticles as Carriers.

Excess large and unstable air bubbles can reduce the compressive strength of hardened concrete, and traditional defoamers always fail because of adsorption and encapsulation on cement with the progress of cement hydration in later stages. It is necessary to develop a novel defoamer that shows a sustained defoaming ability in fresh concrete. A novel slow-release defoamer for concrete using porous nanoparticles as carriers is reported for the first time.

Anionic Copolymers with Different Charge Densities for Regulating the Properties of Cement Pastes.

Self-compacting concrete (SCC) is an extremely flowable concrete, which increases the probability of segregation and bleeding. Viscosity-modifying admixtures (VMAs) have been developed to improve the stability of SCC. Synthetic polymer VMAs have excellent water solubility and stability, and can be easily chemically prepared and modified.

Preparation and Properties of Different Polyether-Type Defoamers for Concrete.

In this study, a series of polyether-type defoamers for concrete which consist of the same alkyl chain (hydrophobic part) but different polyether chains (hydrophilic part) was prepared, and the structure-property relationship of the defoamers was investigated for the first time. Using oleyl alcohol (OA) as the starting agent (alkyl chain), the polyether defoamers with different polyether chains were prepared by changing the amount and sequence of ethylene oxide (EO) and propylene oxide (PO) units. The properties of different defoamers were tested in aqueous solutions, and fresh and hardened mortars; the structure-property relationship of the defoamers was thus studied.