Mechanical properties of alkali activated ground SiMn slag mortars with different types of aggregates

Abstract

h i g h l i g h t s SiMn slag has been implemented as substrate for alkali activated mortars. Two types of alkali activators have been used: waterglass and sodium hydroxide. Silica sand, limestone and recycled concrete finer fraction have been used as sand. Mortars prepared with silica sand offered the best performance in mechanical tests.

Corrosion resistance of steel reinforcements embedded in alkali activated ground granulated SiMn slag mortars

“…Regarding insoluble residue, the obtained result was a 3.35% following the standard UNE 196-2-2014 [35]. Therefore, as commented in other previous studies [27,29], the high content of silicon, calcium and aluminium oxides of this slag, together with its content of reactive silica and vitreous phase, make this material able to be alkali-activated. Negative LOI value could be associated to oxidation of S-rich species in the slag [17].…”

“…In fact, it has been previously seen in Table 3 that the total porosity of the mortar practically does not change after the carbonation process in the case of using WG. Also during the process there has been a reduction in pore diameter range which could explain the behaviour of this material despite the shrinkage suffered during curing [29]. Additionally, it should be noted that the chemistry of the SiMn slag is different to the materials activated in other works.…”

“…The solution/slag ratio was 0.37 for mortars prepared with NaOH, and 0.40 for those ones prepared with WG. These dosages were chosen from previous studies [29], which evaluated the influence of %Na2O, SiO2/Na2O ratio and activating solution/slag ratio on the following selected control parameters: workability, compressive strength at 7, 28 and 90 days of curing time, setting times and shrinkage at 50% of relative humidity. Silica sand was used as aggregate to prepare the mortars.…”

“…Mortars were prepared using an aggregate/slag ratio of 2/1. In a previous work [29], the mechanical performance and dimensional stability of mortars incorporating different types of aggregates with different aggregate/slag ratios were studied. The best flexural and compressive strength results were obtained for an aggregate/slag ratio of 2/1 when silica sand was used as aggregate.…”

“…Previous studies have shown that it is possible to activate the ground SiMn residue with an efficient grinding process, using NaOH and waterglass as activators [27,28]. High enough mechanical performance was obtained, so it was concluded its possible use for both masonry and structural applications [27][28][29]. However, to completely enable the structural use, it is necessary to check the protection that it offers to steel reinforcements against the most classical corrosion processes.…”