Foam Index measurements on combinations of Air Entraining Agents, Superplasticicers and Fly ash/cement/filler powder mixes

摘要

A series of Foam Index measurements were made with 7 different AEAs (abieticacids/resins/tall oil/tensides), 1 copolymer SuperPlaticizer, 2 different Fly Ashes, 1 blended (80/20OPC/FA) cement, 2 different OPC and 2 inert fillers (limestone and quartz).Foam Index = FI = required dosage of AEA to produce stable foam of a particular binder in aw/p = 2.5 slurry where AEA is added dropwise to a container that is shaken and the foam observedrepeatedly until stable foam is obtained.The objective was to investigate the efficiency of the different AEAs with varying Fly Ashbinders and the effect of mixing sequence of AEA and SP on the problems encounterd with airentrainment with Fly Ash with variable carbon content.The results show: that the ranking of the FI of the seven AEAs are the same for differentOPC/FA binders (with different carbon content); the more carbon the higher the FI, that “tensides”are more robust than “resins”, and that FI in pure OPC binders are very low and not very differentfor the 7 AEAs.When adding SP before AEA the negative effect of carbon on foaming is reduced for mostAEAs, presumably due to adsorption of SP before AEA is introduced in the mix, whereas the FI ofsome (presumably non-adsorbing) AEAs is not affected by SP addition. For those AEA/FAcombinations where the FI is affected by SP, adding SP with the AEA and adding SP after the AEAreduces the efficiency of the AEA. Replacing blended cement with limestone filler and quartz fillerseems to affect FI in terms of the specific surface of the filler added: the more surface that is takenaway the more efficient becomes the AEA. Foaming with pure water