Abstract
Hydrated lime is a historic material currently used in conservation. It hardens slowly by carbonation slowing construction however, supplementary cementitious materials accelerate hardening enhancing strength. Hydrated-lime mortars with rice husk ash–RHA-; ground granulated blastfurnace slag–GGBS- and increasing amounts of two aggregates were studied. Increasing aggregate lowered strength as interfacial zones proliferate; it lowered hygric properties and raised water demand. Aggregate content/composition didn’t affect the high water retention. For the higher aggregate contents (90 days), limestone mortars are c.20% stronger than silica mortars while the (1:1) silica sand mortars are 56% stronger in flexion. Additions increased strength with little impact on hygric properties. GGBS increased strength c.six times. RHA increased strength with little impact on hygric properties due to its great specific surface and high water-demand increasing porosity. GGBS and RHA properties ruling hydrate production and the kinetics of the pozzolanic reaction are considered partially responsible for the mortar property variation.
Highlights
The use of hydrated lime (European designation: CL90s) implies well-known issues such as a slow hardening by carbonation, drying shrinkage and low early and ultimate strengths it offers benefits such as physical and chemical compatibility with historic and traditional masonries, high workability and water retention; and an ease of application and long-lasting plasticity that allow masons to re-work mortars and reset masonry units
Supplementary cementitious materials usually speed up hardening and increase early strength development.This paper investigates the properties of hydrated lime mortars with additions and increasing amounts of two d ifferent types of aggregate
The only exception is the flexural strength of the limestone sand mortar which, rather than lowering, slightly increases with increasing aggregate content
Summary
The use of hydrated lime (European designation: CL90s) implies well-known issues such as a slow hardening by carbonation, drying shrinkage and low early and ultimate strengths it offers benefits such as physical and chemical compatibility with historic and traditional masonries, high workability and water retention; and an ease of application and long-lasting plasticity that allow masons to re-work mortars and reset masonry units. Supplementary cementitious materials usually speed up hardening and increase early strength development.This paper investigates the properties of hydrated lime mortars with additions (rice husk ash –RHA- and ground granulated blastfurnace slag –GGBS-) and increasing amounts of two d ifferent types of aggregate. Six hydrated lime mortars were studied with increasing proportions of either Portland limestone or silica aggregate. The 3:1 silica aggregate mortar was further studied replacing 10, 20 and 30% of lime with either RHA or GGBS
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