Lime-sand mortar

Up until the introduction and common usage of acid resistant mortar, the linings were laid up in the usual Portland cement/lime/sand mortar mixes. Although subjected to occasional acid attack conditions, these linings were able to last many years, due to the fact that they were kept mostly dry and could be repaired as needed by simply sandblasting and tuckpointing the damaged mortar areas. They are seldom specified today, because of their inability to resist acid attack in combination with low flue gas temperatures and the effects of positive pressure conditions as described above. 

Traditional lime-sand mortars, using fat lime as the binder, have proved to be durable over many centuries. From the builder s viewpoint, however, they became uneconomic, as they set slowly by loss of water and hardened even more slowly by absorption of carbon dioxide, forming a calcium carbonate-bonded... 

A lime-sand mortar, known as coarse stuff , is generally prepared first. It may be produced by ... 

Mortar, a mixture of lime, sand, and water, has been used in construction for thousands of years. The Appian Way, many early Roman and Greek buildings, and the Great Wall of China were constructed using mortar containing lime. In the Western Hemisphere, the Incas and Mayans used lime in mortar. The composition of mortar can vary rather widely, but the usual composition is about one-fourth lime, three-fourths sand, and a small amount of water to make the mixture into a paste. Essential ingredients are a solid such as sand and lime that is converted to Ca(OH)2 by reaction with water. 

The nature of mortar has changed considerably over time. The primitive clay based mortars gave way to the lime-sand formulation of the Romans with additions of plaster, crushed brick, and/or volcanic earth (pozzolan). The rediscovery of natural cements occurred in the eighteenth century and finally Portland cement was developed. Mortars in use changed accordingly to include the new products. In each case the type, size and amount of charge added in the mix has a large influence on properties such as the bulk density and porosity of the final product. 

The effect of acid rain on mortars will depend on the particular mortar in consideration. The most susceptible mortars will be the lime-sand ones. The carbonated lime will be particularly attacked due to the small crystal size of the formed calcite (19,20). The resulting calcium sulfate can crystallize as gypsum [CaS0. 2H20] inducing mechanical stresses into the matrix of the mortar. 

Mortar (sometimes called cement) is used to bond surfaces like bricks together, but also for plastering walls. Historically, it has been composed variously of lime, sand, clay, volcanic rock and ash, brick dust, and potsherds. Early lime mortars that set simply by reaction between the lime and carbon dioxide in the air offered little protection from deleterious effects of water to the structure. Aggregate mortars that incorporatepozzolans and silicates, which react to bond with calcium, do not need C02, and some can even set underwater. These are called hydraulic mortars, and offer durability in weather, but are less suitable for situations where plasticity is needed, as in restoration projects, for example. 

Nevertheless, there is firm evidence of the use of lime in the Near East, dating from about 8,000 years ago, and in Lepenski Vir, in the former Yugoslavia, a floor, dated 6,000 B.C., was excavated in the 1960s. That consisted of a type of mortar made from lime, sand, clay and water. 

Mortar a mixture consisting of a binder (cement and/or hydrated lime), sand and water and the hardened product of the mixture. 

Calcium hydroxide Ca(OH)2, called slaked lime, is formed by the action of water on calcined limestone. A mixture of slaked lime, sand and water has been used since ancient times as a mortar to bind stone to stone in bricklaying and as an internal and external plaster for walls. Carbon dioxide from the air reacts with the calcium hydroxide, forming calcium carbonate. Finally the mortar becomes a hard mixture of this carbonate and silicate from the sand. Although the composition of lime and the mechanism of its hardening were unknown in ancient times, considerable practical knowledge was developed and documented. 

Mortar Portland cement Hydrated lime Sand Acrylic latex (50% solids)... 

LIME MORTAR. Contains hydrated lime. sand. Portland cement, coloring. During the period when mortar is liquid, aluminum alloys show etching which ceases when the mortar dries because of the formation of a protective film. It is good engineering practice to protect aluminum alloys contacting mortar in a faying surface to minimize crevice corrosion. See also Ref (1) p. 129. (2) p. 161, (3) p. 72. 

The most significant losses of original material involved the lime bedding mortars. In many areas complete loss of all original lime mortar was evident, and in some aU of the lime binder had been washed out of the joints, leaving just the sand. The natural cement pointing mortar had also suffered some losses and had allowed water to infiltrate, probably facilitating some of the lime moitar losses. More noticeably, the natural cement had weathered and many joints had lost adhesion and the ability to resist water infiltration. 

A mixture of slaked lime, sand, and water composes the mortar used in bricklaying. Excess water in the mortar is absorbed by the bricks and then lost by evaporation. In the final setting of the mortar, C02(g) from the air reacts with Ca(OH)2(s) and converts it to CaC03(s), as shown below ... 

Morta.r, Mortar, principally slaked lime and sand, sets because of the evaporation of water, the deposition of calcium hydroxide, and the absorption of water by the bricks or cement blocks, foUowed by hardening as a result of the absorption and reaction of carbon dioxide. 

Hydraulic limes (84) may be used for mortar, stucco, or the scratch coat for plaster. They harden slowly under water, whereas high calcium limes, after slaking with water, harden in air to form the carbonate but not under water at ordinary temperatures. However, at elevated temperatures achieved with steam curing, lime—silica sand mixtures do react to produce durable products such as sand—lime bricks. 

The seven model mortar samples with proteinaceous binders and a blank were prepared in the authors laboratory and are described in Table 6.5. The binders were added to the basic mixture containing sand, lime and water (4 1 1 w/w/w). The samples were shaped into plates of dimensions 20x10x2.5 cm and left to dry under outdoor conditions. 

Calcium hydroxide is known as hydrated lime or slaked lime, and it is used extensively in some applications because it is less expensive than NaOH or KOH. It reacts with C02 to form CaC03, which binds particles of sand and gravel together in mortar and cement. 

ABSTRACT The aim of this study was to test portable infrared spectroscopy for non-destructive analysis of ancient construction mortar. Mortar samples from the House of the Vestals, in Pompeii, Italy, were initially examined with traditional analytical techniques, including X-ray fluorescence, X-ray diffraction and thin section analysis. These techniques were used to establish mineralogical and chemical profiles of the samples and to verify the results of experimental field methods. Results showed the lime-based binder was composed of calcite, and the volcanic sand aggregate contained clinopyroxene, plagioclase, sanidine and olivine crystals. 

Nonhydraulic cements were among the most common of the ancient cements. The relatively high solubilities of portlandite (Ca[OH]2) and gypsum means that they deteriorate rapidly in moist or wet environments. Many decades ago, the Romans used lime-based cements and mortars (cement plus sand) by ramming the wet pastes... 

Mellon Institute on the effect of adding sugar to sand-lime bricks. It was found that the addition of 6% sugar (this amounts to 13 lb. of sugar per 1000 bricks) increased the tensile strength by about 60%. To summarize, it seems that sucrose exerts a beneficial effect on mortar and on sand-lime brick but a detrimental effect on Portland cement. 

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