Effect of utilization of air entraining and mineral admixtures on transport properties and freeze-thaw resistance of cementitious systems

In this study, effect of air-entraining and different type mineral admixtures on the fresh and some hardened state properties of cementitious systems were investigated. Moreover, it was also observed whether used mineral and chemical admixtures were compatible with cement or not. For this aim, different paste and mortar mixture combinations were prepared by using a CEM I 42.5R type cement, a polycarboxylate-ether based water reducing admixture, an air entraining admixture (AEA), a silica fume and fly ash as the mineral admixture. In addition to the control mixture containing no AEA and mineral admixtures, three more series of mixtures were prepared. In the first and second series, silica fume and fly ash were replaced by 30 w.t.% and 10 w.t.% of cement, respectively. In the third series, both silica fume and fly ash were used as 30 w.t.% and 10 w.t.% of cement. In all mixtures, new mixtures were prepared by adding AEA at a ratio of 0.1 w.t.% of cement. In this way, a total of eight different pastes and mortar mixtures were produced. In all cement paste mixtures, water/cement ratio (w/c) was kept constant as 0.35. In all mortar mixtures, w/c ratio, sand/binder ratio and flow value were kept constant as 0.485, 2.75 and 270 ± 20 mm, respectively. Marsh funnel and mini-slump tests were carried out in paste mixtures. Time-dependent flow change, 3, 7, 28 and 90-day compressive strengths, 90-day water absorption capacity and 90-day freeze-thaw resistance were measured in mortar mixtures. According to test results, utilization of mineral and air-entraining admixtures positively affected the fresh state properties of paste mixtures. The use of silica fume and fly ash with air entraining admixture in mortar mixtures had a positive effect on the time-dependent flow change behavior of the mixtures. Usage of mineral admixture have a negative effect on the early age strength of the mixtures but have a positive effect on the advanced age strength. This behavior was not significantly affected by the addition of AEA in to the mixtures. The 90-day water absorption values of the mortar mixtures containing mineral admixture were observed to be less compared to that of control mixture. In terms of freeze-thaw resistance, the most successful mixture was found to be mixture having ternary cementitious system such as both fly ash and silica fume and containing AEA.