Investigation into the Heat of Hydration and Alkali Silica Reactivity of Sustainable Ultrahigh Strength Concrete with Foundry Sand

Abstract

This study presents the hydration reactivity and alkali silica reaction (ASR) of ultrahigh strength concrete (UHSC) that has been made more sustainable by using spent foundry sand. Spent foundry sand not only is sustainable but has supplementary cementitious material (SCM) characteristics. Two series of UHSC mixtures were prepared using a nonreactive and reactive sand (in terms of ASR) to investigate both the impact of a more reactive aggregate and the use of spent foundry sand. Conduction calorimetry was used to monitor the heat of hydration maintained under isothermal conditions, while ASR was investigated using the accelerated mortar bar test (AMBT). Additionally, the compressive strengths were measured for both series of mixtures at 7, 14, and 28 days to confirm high strength requirements. The compressive strengths ranged from 85 MPa (12,345 psi) to 181.78 MPa (26,365 psi). This result demonstrates that a UHSC mixture was produced. The calorimetry results revealed a slight acceleration in the heat of hydration flow curve compared to the control from both aggregates indicating increased hydration reactivity from the addition of foundry waste. The combination of foundry sand and reactive sand was found to increase ASR reactivity with increasing additions of foundry sand up to 30% replacement.

Mechanical Properties of Ultra High Performance Fiber Reinforced Concrete Made with Foundry Sand

“…This ultimately demonstrates an impact due to FS replacement on HSC up to 20%, but no impact up to 30%. Again, these results can be explained by similar results obtained by other authors [1][2][3][4][5][20][21][22][23][24][25][26][27][28][29][30], in which FS has an impact on density, workability, and has SCM like abilities up to 20% replacement, which results in the flexural strength improvement up to the same amount.…”

“…However, there was no statistical significance between 0 -FS and 20 -FS, which is a favorable result as it shows that FS has no impact at a 20% replacement level, which can increase the sustainability of the material without sacrificing splitting tensile strength. As with the compressive strength results the effect of the FS reducing density and workability, along with the literature [29] demonstrating a reduction of SCM ability from the FS, had the same effect on the splitting-tensile strength, which is expected based on the literature [1][2][3][4][5][20][21][22][23][24][25][26][27][28][29].…”

“…With the increase in FS content, its workability is impacted and there by compaction is affected thus decreasing the concrete's density and consequently its strength. Additionally, Siddique et al [1,2] and other authors from other studies [3,4,12,21] describe the SCM abilities of FS due to its high siliceous content, and have also used FS as an SCM (replacing cement content) as opposed to an aggregate replacement. However, these authors demonstrate that FS is better suited as a an aggregate than an SCM due to its size being larger than traditional SCMs (silica fume, fly ash, etc.).…”

“…200 sieve to remove any fine dust and particles. This helped to ensure there was no water lost due to fine dust River Sand Foundry Sand particles as recommended by the literature [5,7,[19][20][21][22]. After washing, the aggregates were oven dried at 110º C (230º F) for a minimum of 24 hours to achieve a 0% moisture content.…”

“…After thorough mixing, the HRWRA was added with the remaining 25% of the water. This mixing sequence was used based on of the literature and experience [20][21][22][23][24][25].…”