FOAM INDEX MEASUREMENTS ON MIXES OF AIR ENTRAINING AGENTS, SUPERPLASTICIZERS AND FLY ASH-CEMENT- FILLER BLENDS

Foam Index (FI) measurements were made to investigate the foaming efficiency of different AEAs with varying cements (OPC, blended), fly ashes (FA) and fillers, and the effect on foaming of mixing sequence of AEA and SP. Ranking of the FI among the seven AEAs is the same for different OPC and FA binders (including different carbon contents). FA mixes with higher carbon show higher FI (i.e. more AEA needed to get stable foam) and FI in pure OPC is very low and not very different among the 7 AEAs as expected. Adding a low dosage of copolymer SP before both resin and tenside AEA could reduce the negative effect on foaming of carbon content in one of the FA blends. The low FIs of AEAs in pure OPC seemed unaffected when adding SP before AEA. Adding SP after and with the AEA reduced the efficiency of most AEAs markedly, seen as foam bursting after adding/shaking for both OPC and FA blends. Replacing parts of blended (FA) cement with limestone- and quartz filler reduced FI, presumably due to reduced carbon in the mix.