Title: Assessing Standard Tests for Admixtured Chlorides in Calcium Aluminate and Calcium Sulfoaluminate Cement Systems
Author(s): Ahmed Abdulhaq Ahmed and David Trejo
Publication: Materials Journal
Appears on pages(s): 71-83
Keywords: acid-soluble chlorides; admixed chlorides; ASTM C1152; auto-titration; calcium aluminate cement; calcium-sulfoaluminate cement; specialty cements; total chlorides
ASTM C1152 is used to determine, in most cases, the total chloride
concentration of hydraulic cement, mortar, or concrete systems. When these test standards were first developed, only ordinary portland cement (OPC) samples were evaluated. There is limited information on the test’s applicability to calcium aluminate cement (CAC) and calcium sulfoaluminate cement (CSA). The standard also requires manual titration, which is slow and costly. This study compares results using manual titration, as described in ASTM C1152, with results using auto-titration for OPC, CAC, and CSA. This study then investigates whether the ASTM C1152 procedure, modified using auto-titration, can be used to provide a reasonable estimate of total admixed chloride concentrations for the cementitious systems. Results indicate that there is no significant difference in results from manual and auto-titration for all systems. However, the results from the CSA indicate that acid-soluble extraction followed by auto-titration significantly underestimates the total admixed chloride concentration.