Effect of coarse filler on shrinkages and dynamic mechanical properties of epoxy grouts

Effect of coarse filler on shrinkages and dynamic mechanical properties of epoxy grouts

Structures are designed and constructed for a certain lifetime based on its constituent materials, level of quality control, surrounding environment and accidental loads experienced during service. Structures that are situated in an adverse environment are susceptible to material loss and cracks over their ageing service life. Often, advanced composite materials offer substantially enhanced mechanical, durability and constructability
related properties essential for durable repair of the deteriorated structure. Infill material is used to ensure a supporting bed for a grouted repair. Epoxy grouts are used
for repairing and rehabilitating structures, such as foundations, bridges, piers, transportation pipelines, etc., because they are resistant to typical chemicals and possess superior mechanical properties than other grouts. The resin based infill used inside the void or cracked space of the repair is vulnerable to shrinkage. When these filled grouts have high resin content, cracks can develop from residual stresses, which can affect the load transfer performance. As a result, interlayer separation and cracking
of infill layer can occur in a grouted repair. In this study, volumetric shrinkage of two epoxy grouts was measured over 28 days using a Pycnometer. The highest volumetric shrinkage measured after 7 days was found to be 2.72%. The results suggest that the volumetric shrinkage can be reduced to 1.1% after 7 days, through the introduction of a coarse aggregate filler; a 2.5 times reduction in shrinkage. About 98% and 92% of the total shrinkage over the 28 day period, of the unfilled and filled grouts respectively, was found to occur within 7 days of mixing. The gel-time shrinkages were calculated,
to determine the 'post-gel' part of the curing contraction which subsequently produces residual stresses in the hardened grout systems. The dynamic thermal behaviour of the
grouts were also characterised to determine the range of in-situ application.

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