Behaviour of cementitious matrices subjected to the combined action of chloride ions and carbonation

TY - JOUR

T1 - Behaviour of cementitious matrices subjected to the combined action of chloride ions and carbonation

AU - Malheiro, Raphaele

AU - Camões, Aires

AU - Meira, Gibson

AU - Amorim, Maria Teresa

AU - Castro-Gomes, João

AU - Ferreira, Rui Miguel

PY - 2018/10/18

Y1 - 2018/10/18

N2 - Carbonation and chloride action are the two leading causes of degradation in reinforced concrete structures. Despite the combined action of these two mechanisms being a reality, there is little research on the effect of this combination in cementitious matrices. Furthermore, the incorporation of fly ash in cementitious matrices has been frequently used in order to make the matrix more resistant to the action of chlorides. On the other hand, it is known that Ca(OH)2 existing in the matrix is consumed by the pozzolanic reactions, which makes easier the carbonation front advance. Therefore, this paper presents a study of the behavior of cementitious matrices, with and without fly ash, subjected to the combined action of chlorides and carbonation. Two different kinds of mortars were produced: reference (only cement CEM I 42.5R) and fly ash mortar (40% replacement of cement). After curing, the specimens were subjected to three different wetting-drying cycles, considering NaCl solutions and CO2 atmospheres. Afterwards, chloride profiles and carbonation front were measured. Results show that carbonation has a direct influence on chloride penetration, decreasing it for cement mortars with 0% fly ash and increasing it for mortars with 40% cement replacement by fly ash. Moreover, the evolution of carbonation is also influenced by chloride presence, which decreases under the combined action.

AB - Carbonation and chloride action are the two leading causes of degradation in reinforced concrete structures. Despite the combined action of these two mechanisms being a reality, there is little research on the effect of this combination in cementitious matrices. Furthermore, the incorporation of fly ash in cementitious matrices has been frequently used in order to make the matrix more resistant to the action of chlorides. On the other hand, it is known that Ca(OH)2 existing in the matrix is consumed by the pozzolanic reactions, which makes easier the carbonation front advance. Therefore, this paper presents a study of the behavior of cementitious matrices, with and without fly ash, subjected to the combined action of chlorides and carbonation. Two different kinds of mortars were produced: reference (only cement CEM I 42.5R) and fly ash mortar (40% replacement of cement). After curing, the specimens were subjected to three different wetting-drying cycles, considering NaCl solutions and CO2 atmospheres. Afterwards, chloride profiles and carbonation front were measured. Results show that carbonation has a direct influence on chloride penetration, decreasing it for cement mortars with 0% fly ash and increasing it for mortars with 40% cement replacement by fly ash. Moreover, the evolution of carbonation is also influenced by chloride presence, which decreases under the combined action.

KW - Carbonation

KW - Chloride

KW - Fly ash

KW - Mortar

KW - Wetting-drying cycles

UR - http://www.scopus.com/inward/record.url?scp=85055637493&partnerID=8YFLogxK

U2 - 10.1590/S1517-707620180003.0496

DO - 10.1590/S1517-707620180003.0496

M3 - Article

VL - 23

JO - Revista Materia

JF - Revista Materia

SN - 1517-7076

IS - 3

M1 - e-12162

ER -