Does polyacrylamide improve toughness in AACM?

Polyacrylamide (PAM) is a water-soluble polymer widely used as a modifier for cement-based materials due to its significant modification effects, environmental friendliness, and low cost. However, there is limited research on improving toughness in AACM by PAM, and the toughening mechanism remains to be determined.

Which functional groups does polyacrylamide have?

Polyacrylamide contains CH 2 and NH 2 functional groups. The NH 2 groups, which can hydrolyze, are likely to interact with cement phases, forming products that remain dispersed uniformly in the rest of the materials, modifying the physical and mechanical properties of the product.

What is polyacrylamide (PAM)?

Polyacrylamide (PAM) is a modifier widely used in various fields. PAM is synthesized by the polymerization of acrylamide monomers . The chemical structure of PAM contains amide groups, which can hydrolyze into carboxyl groups and other hydrophilic functional groups , capable of establishing hydrogen bonds with water molecules .

How does polyacrylamide affect weight loss?

The use of polyacrylamide in cement results in a decrease in weight loss with increasing concentration, up to 3.0%. These improvements might be attributed to the filling of pores in the porous cement paste with polyacrylamide.

What is the retardation process in the presence of polyacrylamide?

The retardation process in cement paste is affected by the presence of polyacrylamide through a chemical interaction between the hydrated cement phases (C 3 S, C 2 S and C 3 A) and the polar functional groups of the organic polymer. These amorphous materials, which are relatively insoluble, are scattered between the crystalline mass of cement paste.

How does polyacrylamide affect the hardening of cement?

Polyacrylamide may form polymer films over the hydrating cement particles, interfering with the hydration process and thereby the setting and hardening of cement. However, it may also increase the plasticity required for good mixing, which may cause an improvement in strength.