Measurement of Sodium and Potassium in Portland Cement by Flame Atomic Absorption Method

Introduction

Portland cement may be classified into 6 types according to the intended use, including ordinary, high- early-strength, ultra-early-strength, moderate-heat, low-heat, and sulfate-resistant, all of which are available in low-alkali types. The low-alkali types contain concentrations of Na and K that are suppressed to low levels, as they are considered to be causative agents of the alkali-aggregate reaction. Low alkalinity is defined based on total alkalinity, and is classified as such when its content is 0.6 % or less. Total alkalinity (Na₂Oeq) = Na₂O + 0.658 × K₂O where, Na₂O:Percent concentration (%) of sodium oxide in Portland cement K₂O: Percent concentration (%) of potassium oxide in Portland cement Here, using flame atomic absorption method, we introduce an example of analysis of Na and K in a standard sample of Portland cement (211R) obtained from the Japan Cement Association to determine their respective concentrations.

March 27, 2012 GMT