Sustainable and Durable Performance of Pozzolanic Additions to Prevent Alkali-Silica Reaction (ASR) Promoted by Aggregates with Different Reaction Rates

Esperanza Menéndez,Hairon Recino,Ricardo García-Roves,Cristina Argiz,Miguel Ángel Sanjuán

doi:10.3390/app10249042

Abstract

The increased use of industrial wastes and by-products to produce concretes and blended cements is a lever to achieve carbon neutrality. Furthermore, they could improve their durability. Some pozzolanic additions can minimize the alkali-silica reaction (ASR), which is a well-known deleterious process that occurs between some reactive aggregates and the alkaline pore solution found in mortars and concretes. This work quantifies the efficiency of four pozzolanic materials (natural pozzolan, P, siliceous coal fly ash, V, silica fume, D, and blast-furnace slag, S) assessed by means of compressive strength testing, open porosity, ASR-expansion measurements, and SEM microscopy. Accelerated expansion tests were performed in mortar bars with a cement/sand ratio of 1/2.25 and a water/cement ratio of 0.47, two reactive aggregates and a non-reactive one. The major contributions of this paper are: (i) The more aggregate reactivity is, the higher ASR mitigation level was found when additions were added and (ii) The best additions for ASR inhibition are silica fume and fly ash.

Highlights

Eco-innovation is any breakthrough which makes progress towards circular economy and mitigation of the climate change
Compressive strength tests were performed for all the mortars made with three aggregates (non-reactive siliceous sand, ASJ_2 (Figure 2); siliceous gravel with moderate reactivity, VB (Figure 3); and a reactive siliceous pebble, ASJ_12 (Figure 4)), and blended cements Mechanical performance was assessed at 2, 7 and 28–days following the procedure prescribed in the European standard EN
The conclusions extracted from this research work are as follows: (1) Blended cements made with natural pozzolan, P, siliceous coal fly ash, V, silica fume, D, and blast-furnace slag, S were found to be effective in alleviating alkali-silica reaction (ASR) expansion in mortar bars; (2) The more reactivity of the aggregate is, the higher ASR mitigation level was found in blended cements; (3) The best additions with regard to the ASR inhibition are the silica fume and the siliceous fly ash; (4) The higher addition contents provide improved ASR inhibition performances, mechanical properties are negatively affected at the same time

Summary

Introduction

Eco-innovation is any breakthrough which makes progress towards circular economy and mitigation of the climate change. Both aspects are part of sustainable development. Strategy for Europe, published in 2020 [1], underscores the prime concern that industries must face to reach the goal of carbon neutrality [2]. Europe plays a crucial role promoting clear requirements for a Zero Waste Circular Economy over the years across several policies. The European Commission launched in 2011 the Roadmap to a Resource Efficient. Europe [3] with criteria to move towards zero waste in Europe.

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