Mortars Elastic deformation

The significant differences in the moduli of latexes and the cement hydrates (elastic moduli 0.001-10 GPa and 10-30 GPa respectively) causes most LMMs and LMCs to have a higher deformability and elasticity than ordinary cement mortar and concrete. Depending on the polymer type and polymer-cement ratio, the deformability and elastic modulus tends to initially increase with an increase in the polymer-cement ratio and subsequently decrease at higher ratios. Poisson s ratio however is only marginally affected [87, 94, 98]. 

Latex-modified mortar and concrete contain polymers (modulus of elasticity, 0.001-10 x lO kgf/cm ) with considerably smaller modulus of elasticity compared to cement hydrates (modulus of elasticity, 10 30 x 10 kg cm ). Consequently, their deformation behavior and ductil ity (or extensibility) can differ to a great extent from those of ordinary cement mortar and concrete. Most latex-modified mortars and concretes provide a higher deformation, ductility (or extensibility), and elasticity than ordinary cement mortar and concrete, dieir magnitude depending on polymer type and polymer-cement ratio. 

The mortar used in the execution of masonry walls is made up of different combinations of cement, sand, and fines. Resistance achieved by mortar is usually less than that of brick. Mortar introduces a non-linear behavior in tens deformational level that causes significant inelastic deformations in the masonry wall [44]. Some studies [45] provide graphs on the variation of the elastic modulus of concrete which can be assimilated to the mortar. 

There are many poor examples of interventions on monuments with concrete, which was supposed to cooperate as repair material with the old masonry. The destructive consequences from the use of incompatible to authentic matrix repair materials are mostly related to different physicochemical characteristics of cement-based or polymeric matrix repair materials, which block the moisture movement, because of very low porosity and different porosity properties in comparison to old mortars. In addition, the aforementioned repair materials differ in elasticity from the existing old ones and consequently in deformability under the action of mechanical or hydrothermal loads. 

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