Effect of Coarse Aggregate Type on Chloride Ion Penetration in Concrete

Project Details
STATE

WI

SOURCE

TRID

START DATE

05/25/17

END DATE

02/20/18

RESEARCHERS

Hani H Titi, Habib Tabatabai

SPONSORS

Department of Civil and Environmental Engineering, University of Wisconsin-Milwaukee

KEYWORDS

Bridge decks; Chloride content; Chlorides; Coarse aggregates; Ions; Rapid Chloride Penetration Test; Bridges and other structures; Highways; Materials; Pavements

Project description

Long-term durability and sustainability of crucial infrastructure systems such as bridges and pavements are of utmost importance for the economic health of any society. Understanding factors that affect long-term deterioration of reinforced concrete structures can help enhance durability and sustainability of these systems. This paper investigates the effect of the type of coarse aggregate used in concrete on chloride ions penetrability. Twelve coarse aggregate types of different geologic formations (sedimentary, igneous, and metamorphic) were used to prepare fresh concrete in which silica fume and class C fly ash were used. All mix parameters including gradation and volumes of different aggregates were held constant in different mixes with the only variable being the aggregate type. The Rapid Chloride Penetration Tests were conducted on concrete specimens made with various aggregate types at ages of 28, 56, 91 and 365?days. Analysis of test results showed that the aggregate type as well as aggregate absorption rates have significant influence on the electrical charges passed through concrete, especially in early ages of concrete containing aggregates with sedimentary rock origin and relatively high absorption. These specimens exhibited the highest RCPT results indicating higher capacity to allow chloride ion penetration when compared to specimens with igneous and metamorphic rock aggregate of lower absorption values. This influence (discrepancy) diminishes with time for both aggregate type and absorption rates in terms of the magnitude of measured total charge passed.
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