Abstract:
Understanding the effects of various superplasticizer (SP) types on the rheological characteristics
of foamed cement pastes, as well as on the physical and mechanical characteristics of environmentally
friendly porous lightweight aggregate concretes, is crucial. Differently extending the setting time of
Portland cement (PC) pastes are three tested superplasticizers, lignosulfonates (LS), polycarboxylates
(PCX), polyacrylates (PA), air-entraining additive (AM), and their mixtures. The findings reveal that
PA, either used alone or in conjunction with AM, only slightly delays the setting time of PC paste.
The metakaolin additive (MKA) to PC ratio, as well as AM, determine the dynamic viscosity of PC
pastes. In pastes containing AM and PA, raising the MKA to PC ratio enables more air to be entrapped,
which leads to uniform pore distribution and an increase in apparent porosity of 2.2 times. After 7
days of hardening, an LWAC sample series with an increased MKA to PC ratio showed a drop in
compressive strength of up to 14 times; however, after 56 days of hardening, a rise in compressive
strength was shown as a trend. The results obtained can be used for the production of high-quality
lightweight concretes with the use of different additives.
