Effect of material and technological factors on the properties of cement-lime mortars and mortars with plasticizing admixture

摘要

Lime is a commonly used constituent of cement-based mortars and plasters used in masonry. Lime improves consistency and workability of the fresh mortars [1, 11], while improving the stability of the fresh mortar in relation to its water retention [10, 15, 16]. Hardened cement-lime mortars also exhibit lower compressive strength and slightly higher flexural strength, what in turn makes the mortars weaker but more deformable, what is a desired trait for masonry [6, 7, 8].In Polish construction practice, lime has been mainly perceived and treated as a plasticizing agent. Therefore, when plasticizing admixtures for masonry mortars and plasters were introduced, they were often regarded as a direct substitute for lime, and this trend is still present in the current Polish construction practice [14]. The perception of plasticizing admixtures as direct substitutes for lime leads to a common belief that their effect on the properties of fresh masonry mortars and plasters is also comparable [9]. This can cause problems during construction process, especially taking under consideration the non-stable conditions of making and applying plaster and masonry mortar on the construction site. While the difference of the properties of mortars and plasters has been a subject of comparative studies such as [17], the research into topic of the effect of material and technological factors on the properties of cement-lime mortars and mortars with plasticizing admixture yields little results.