Degradation of Materials Based on Alkali-Activated Blast-Furnace Slag after Exposure to Aggressive Environments

Abstract

The paper summarizes partial results of a study of degradation of materials based on alkali-activated blast-furnace slag (AAS) and comparative on cement CEM III/A 32.5 R after exposure to aggressive environments. It further specifies the possibilities for utilising destructive and non-destructive techniques to determine the progress of degradation and characterizes the degree of their correlation. After 28 days of ageing in a water environment, the produced test specimens (40×40×160 mm beams) were placed in aggressive media (ammonium nitrate solutions; sodium sulfate, rotating water) and after subsequent 28, 56 and 84 days of degradation were subjected to testing. Testing comprised both a destructive form (determination of compressive strength and flexural strength) and a selected non-destructive technique (Impact-echo method). The partial outputs were supplemented by the results acquired from monitoring weight changes. In addition, the development of Ultrasonic Pulse Velocity in relation to the progress of the degradation processes was also monitored. While the exposure of both test specimens to water and sodium sulfate did not result in any significant changes, the exposure to the ammonium nitrate solution exhibited rapid signs of degradation associated with a significant reduction in functional characteristics.

Effect of siliceous sand volume fraction on the properties of alkali-activated slag mortars

“…The granulated blast furnace slag with a BET specific surface area of 1.85 m 2 /g, density of 2.88 g/cm 3 , and 70% contents of amorphous phase was used. The slag was activated using sodium water glass with a silicate modulus of 1.5 (SWG1.5), sodium hydroxide (SH), and sodium carbonate (SC) solutions with the same molarity of 4 mol Na + /dm 3 . More details on the composition of the raw materials can be found in previous work [12].…”

“…Alkali-activated slag (AAS) can be considered as a possible alternative in specific areas of industry. It is advantageous by means of the resistance to aggressive environments [2,3], resistance to higher temperatures [2] or appropriate immobilization of some heavy metals [4]. In addition, AAS potentially have low ecological and economic impact, since the used granulated blast furnace slag is a secondary raw material and also alkaline activators based on the secondary raw materials can be used [5].…”

Experimental Determination of the Coefficient of Thermal Expansion of Hardened Alkali-Activated Slag Pastes

“…In these alternative binders, the reaction of ground granulated blast furnace slag is enhanced by the presence of a high alkalinity activator. Environmental aspects, high resistance to aggressive environments [1,2,3], rapid strength growth [4] and resistance to high temperatures [5] are the main advantages of the AAS materials. One of the major disadvantages of AAS materials is the high susceptibility to significant shrinkage, which is accompanied by the formation of cracks.…”

Monitoring the internal structure behaviour of alkali-activated slag paste: effect of the curing mode

“…These are binders in which the reaction of the ground granulated blast furnace slag is supported by the presence of an activator with high alkalinity. Apart from the environmental aspect, the main advantages of AAS materials include the resistance to an aggressive environment [1][2][3], resistance to high temperatures [4], and a fast increase in strength [5]. However, the main drawback is undoubtedly the tendency for significant shrinkage, accompanied by the occurrence of cracks, which limits the wider use of AAS materials in practice.…”