Investigation of the durability of eco-friendly concrete material incorporating artificial lightweight fine aggregate and pozzolanic minerals under dual sulfate attack

Sulfate erosion, as one of the most aggressive environmental attack, can cause severe damage to concrete infrastructures. This study examined the durability of an eco-friendly lightweight concrete (LWC), made with artificial lightweight fine aggregate and various mineral admixtures exposed to both physical and chemical sulfate attack by performing the change of concrete mass, dynamic elastic modulus, flexural strength, and SEM and XRD analyses. Results show that LWC exhibits better sulfate resistance with less erosion products, i.e., ettringite and gypsum, since the internal curing of LWC contributes to adequate cement hydration that hinders the attack of sulfate ions. With an increase in fly ash volume, worse durability can be observed. A mix of 20% fly ash, 10% metakaolin and 10% blast furnace slag presents excellent sulfate resistance with an increase of 5.43% in flexural strength (even after 35 cycles of dual sulfate attack) compared to its initial 28-day strength. However, the LWC blended with 20% fly ash and 10% metakaolin shows the worst resistance with more erosion products resulting in a maximum strength loss of 23.62% given a 35-cycle attack. With the presented analysis, a theoretical basis for the improvement of concrete durability under severe environmental attack can be provided.