Assessment of the Impact of Inaccuracy and Variability of Material and Selected Technological Factors on Physical and Mechanical Properties of Fresh Masonry Mortars and Plasters

Abstract

The article presented the analysis of the impact that various kinds of technological inaccuracies have on the properties of fresh masonry mortars and plasters. Analyzed were the inaccuracies in dosing of mortar components, namely, water, lime, and air-entraining plasticizing admixture (APA) (±10% of mass), and the effect of variable technological conditions, namely, different mixing intensity (fast, slow, normal) and temperature (5 • C, 20 • C, and 35 • C) during first 72 h after mixing. The impact of differences in the properties of cement and aerial (hydrated) lime originating from different manufacturers was also analyzed. The impact of these factors was determined for consistency, density, air content, compressive, and flexural strength. The sensitivity to changes in the analyzed properties was determined by the coefficient of variation. Changes in the dosing of constituents, mixing speed, and temperature adversely affected strength properties. For mortars with APA, these changes exceeded 20% and reached 40%. The greatest impact was evident in the consistency, especially with an excess of APA, where changes ranged from 6% to 80%. The results showed greater resistance of cement-lime mortars to changing selected technological conditions and errors in measuring the amount of ingredients than mortars with air-entraining plasticizing admixture (APA). Materials 2020, 13, 1382 2 of 29 using waste materials, e.g., concrete waste [5], glass waste [6], brick flour [7], granite flour [8], marble powder [9], and others. A significant part of the research is devoted to modifying mortars with various additives to improve their properties while partially replacing fillers and binders with waste materials.For example, Harbi et al.[10] carried out the experimental work focused on the study of the possibility of using kaolin dust as filler in the sand, combined with additions of glass powder, brick waste, and metakaolin in order to improve the mechanical performance of the mortar. Mixtures containing glass powder and/or metakaolin turned out to be better than those containing brick waste. Similar research was carried out by Boukour and Benmalek [11], who analyzed the effect of two wastes: crushed clay brick and tire rubber aggregate in cement mortar reinforced by a resinous latex. Test results indicated a decrease in water absorption and shrinkage of such cement mortar.Atypical addition to mortar, which has been a subject of research, is recycled polyethylene terephthalate (PET) bottles [12]. Test results of this experiment have indicated that higher compressive and flexural strength can be obtained for thusly modified cement mortars. Other atypical additions to the mortar that have been researched are organic agents as vinegar, gram pulse, and frog contaminated water and their influence on mechanical properties and mortar's performance [13]. It has been concluded that organic materials chosen for the study adversely affect the compressive strength of cement mortars, especially after six months.Research has also been carried o...

Modelling the Influence of Composition on the Properties of Lightweight Plaster Mortar and Multicriteria Optimisation

“…Admixtures are supplied as powders, the typically used low dosages being 0.3–1.5% of the weight of the cement. The researchers have established [ 11 , 12 , 13 , 14 ] that the introduction of additives improves workability and lowers the water demand of the mix, confers air entrainment, or adds waterproofing qualities. These changes have the potential to decrease cracking through improvements in the paste–aggregate bond and to increase the strength of hardened mortars.…”

Comparative Study of Effects of Air-Entraining Plasticizing Admixture and Lime on Physical and Mechanical Properties of Masonry Mortars and Plasters

“…Historically, lime mortars were used; however, currently, cement mortars and cement–lime mortars are most popular in traditionally erected constructions [ 1 ]. In the literature, much attention was paid to the research of traditional mortars and their varieties, types of binder, additives, and admixtures and their influence on physical and mechanical properties [ 3 ] or durability [ 4 ]. Much mortar research concerns aggregate and fillers [ 5 ], and replacing cement with other materials, including waste [ 5 , 6 , 7 , 8 , 9 , 10 ], organic materials [ 11 ], and pozzolans [ 12 , 13 ].…”

“…Therefore, assessing the differences in the use of both is important both from a theoretical and practical point of view, as it may affect the process of construction. Some researchers paid attention to plasticizing admixtures for mortars in their works [ 3 , 23 , 34 ]. Lenart [ 23 ] obtained results that showed that air-entraining and plasticizing admixtures improved workability but decreased compressive strength.…”

Analysis of mortar coating with different types and proportions of chemical admixtures that have water retentivity properties

“…Current research indicates that depending on the type of admixture used, there may be great variability in their properties' results [9], [10], even with compounds with the same chemical name [11]. Viscosity, molar mass and/or nature and quantity of chemical substitution groups can be responsible for these variations [12].…”