Proposal Mixes Process Method for Masonry Structure Laying Mortar

This paper presents an experimental method that procedures high-strength mortars to do with laying structural masonry found on the required properties and conditions of use. Literature research reviews were carried out that developed into the mix proportioning experimental process applied for mortar for laying structural masonry. Compressive strength tests, flexural strength tests, and digital microscope analysis were done to validate the methodology. The experimental program used Portland cement, hydrated lime


Introduction
Mortars are used extensively throughout the world in applications such as wall and ceiling coatings, flooring, or grouting, and even for structural purposes, such as masonry and precast mortar grout (Santos, 2011;Barbosa et al., 2021;Castro et al., 2021;Schuab et al., 2021).In recent years, several companies have been replacing pre-prepared for precast mortars due to the difficulties in stocking and characterizing materials and inaccurate material proportions at the construction site (Barbosa, Santos, 2011;Haddad et al., 2020;Souza, Carvalhais, Santos, 2021).Furthermore, it is significant to consider the inaccuracies found in various current procedures, which can be very specific to regions or material types.Current procedures include seeking the optimal content of binder (clay, phyllites, or lime powder) (Selmo, 1989) for general conditions, without regard to the relationship between the binder and moisture or complying with specific requirements such as the use in building façades (Selmo & Helene, 1991); the binder based on the specific clays available in a particular region (Gomes & Neves, 2002); proportion materials mortars from the maximum consumption of fines, using equations and tables that often do not represent the reality of material in a particular region; proportion materials through adjustments based on particle packing concepts, granulometric curves for sand (Lara et al., 1995); and proportioning through mathematical modeling by SIMPLEX, i.e., network statistical applications (Bahiense et al., 2008;Destefani & Holanda, 2009;Souza et al., 2020a;Souza et al., 2020b).
The mortar performance is subject to its roughness, which is set by the sand particle size (Sahmaran et al., 2009;Lange et al., 1997;Meng et al., 2012;Goble & Cohen, 1999;Peng & Ding, 2009); the final finishing (Faria et al., 2015;Sanchez, 2013); mechanical strength (related to materials) (Pan & Weng, 2012;Peng & Ding, 2009;Kadri & Duval, 2002;Sahmaran et al., 2009), efficient mix procedure forms (Silva, 2006;Allwood & Ashby, 2011;Haddad et al., 2020;Souza, Carvalhais, & Santos, 2021) and the water/cement factor (Motta & Oliveira, 2013;Souza, Carvalhais, & Santos, 2021).This research aims to develop an experimental mix procedure process for structural masonry laying mortar based on local requirements (workability and mechanical properties) and material characteristics.Santos et al. (2018), our research group, developed a mixing process (described hereafter) that demonstrated its feasibility for proportioning mixed coating mortars.The research highlight is process application (method) for materials proportions for laying mortars for structural masonry because most methods set a lower or upper limit for it.In this research, upper and lower limits are obtained.This result is typical of structural masonry, in which the mortar needs to be between 70-100 % of the strength of the brick.

Mix Procedure Process
This method seeks to establish the material's optimum proportions for the mortar mixture where the concepts and appropriate technical and scientific properties depend on the use and materials characteristics.
The simple implementation process was used for high efficiency who used software available to building professionals, such as spreadsheets.Santos et al. (2018) minimized mistakes from errors in mixtures at the application sites and produced structural masonry laying mortar of higher quality and durability through adjustments made to the method.

Conditional Parameters
Materials properties database -Specific mass of all materials.
-Environmental conditions site, strength mortar, and durability requirements.
-Standardization that must comply.
-If the laboratory mixture mortar, it is necessary to simulate the site conditions before the mortar is used at the construction site.
-If the proportion of materials process is carried out at the construction site, at the very least, the appropriate equipment and skilled labor are required.

Mix Proportion Procedure
The mix procedure method is a sequential activity that allows the professional to obtain a proportion of materials, develop experimental tests, and define the most suitable mix proportion mixture for a particular purpose.There are 7 (seven) steps to be performed that allowing to obtain the materials proportion required, such as: Step 1.The aggregate amount in the mixture is obtained Equation (1) that the aggregate void coefficient is considered: Where: C sand = fine aggregate content in the mixture, in %; ɣ u = Specific unit mass of fine aggregate in g/cm³; ɣ r = Specific mass of fine aggregate in g/cm³.
V s = volume of solids in liters.
V t = total volume in liters.
V v = volume of voids in liters.
Step 2. The water/cement ratio of the mixture was determined experimentally, being initially 15%.
Step 3. The binder amount in the mixture was determined.Table 1 shows the expression which is based on Equation 1 and the minimum consumption of the binder.
Step 4. Experimentally adjust the basic mixtures (Table 1): verify the consistency and, if necessary, confirm the amount of water and other materials in the mixture.The following must be observed: -Exudation and/or lack of cohesion of the material.It may be an indication that the amount of binder is insufficient, i.e., to increase the binder in the mixture or adjust the aggregate with the addition of fines.
-High cohesion, i.e., the mortar adheres to the trowel, even when wet.In this case, it is acceptable to add coarser sand and/or decrease the amount of finer sand.
-Mortar is very rough.It is an indication that the grain size of the sand particles is large.In the case of masonry laying mortar, the relationship between the maximum aggregate size and thickness of the gasket should be checked to ensure that it does not exceed ½.If this value is exceeded, the material should be screened, any undesirable material should be removed, and the dosing procedure should be remade.
-It is possible to control the insertion of any additions/additives to make the mortar denser and more strength or incorporate more air to make the mixture more expansive.It is important to indicate any plasticizers or other additives (super and hyper) or additions (silica fume or metakaolin) to obtain high-strength mortar.Step 5. Mortar properties: the main elements are as follows: -In the fresh state: consistency, cohesion, and water retention, which will ensure the workability required during the application process.
-In the hardened state: due to compressive strength and flexural strength, indicating the bearing capacity of the material.
Step 6.The ideal proportions in the mixed procedure mixture: define the most suitable mixture for the conditions of use that also follows the material parameters.These are works like mixed design characteristics that correspond to the specified value associated with a confidence interval, which can be unilateral or bilateral, according to Equation 2.
Where: F d : mix design limit of a certain property of the mortar.
F k : characteristic limit of a certain property of the mortar.
s: is the sample standard deviation estimated by linear regression of ownership (vertical axis -y) and the constituents of the materials in a percentage of volume (x-axis -x); water/cement ratio, to 14% at the beginning of the calculation, which is a higher consumption of cement than adequate because the maximum diameter and fineness modulus sand are 2.4 mm and 3.11, respectively.
-Binder: the ideal mix design in the mixture adopted a process of approximation points that mid-point to stronger mixtures (higher cement consumption -see Table 2).The specific mass and unit mass were 3.1 kg/l and 1.70 kg/l for cement, 2.8 kg/l, and 0.50 kg/l for lime, respectively.The data were provided by the manufacturers.
-Mix proportions: the workability adopted was 260±10 mm.The mortar mixtures showed great cohesion that was suitable for use (Monhamadian, 2013) but, some corrections were made due to workability, see Table 3.Despite mixture corrections, the binder/aggregate ratio (by volume) was constant at 0.40.For workability, it was necessary to increase the water/dry materials ratio from 0.16 to 0.18, i.e., 11%.

Optimum Proportion
The age of 14 days was chosen to evaluate the dosage, as this is a reasonable period for practice in works and laboratories and is an age in which the strength of the laying mortar tends to reach values close to the maximum.
The 14 days of age is a reasonable period for construction sites and laboratories because compressive strength is near 90% last compressive strength, i.e., 28 days of age.The ANOVA tool shows linear regression, see Figure 3, with a reliability of 95%.Therefore, it is possible to find values for compression strength (f c )) between 9.991 MPa and 12.409 MPa.These mortar mixtures are shown in Table 4 and Figures 3 and 5.The yellow area is the ratio of materials limits for specified properties.Figure 4 shows a correlation between Flexural strength and Compressive strength, according to the results found for each mixture.The yellow area, see Figure 5, is the ratio of materials limits, i.e., between 1.754 MPa and 2.465 MPa.
Through the graphs (Figures 3 and 5) performed approach research the three dosage mixtures through polynomial curves to the 2nd degree, which R² equals 1.These equations are valid for these research materials, conditions, and in the range evaluated in each property.Finally, the most suitable proportion materials were defined for materials, conditions, and mechanical properties (minimum and maximum limits).
jms.ccsenet t.org        makes it difficult for any deformation of the elements to accommodate.Moreover, this excess binder tends to create higher retraction, causing several cracks and a reduction of the resistance capacity of the masonry.The amount and size of pores tend to decrease with increasing amounts of cement, as predicted in the bibliography (Souza et al., 2020a).Given the above, it appears that the sustainable mixture was closer to the 3rd mixture than the one with fewer pores, and these were more widely spaced and, therefore more strength and durable.

Conclusions
The results and images allowed confirmation and interaction between the concepts and knowledge covered, proving the feasibility of the proposed procedures and techniques.However, above all, the results allow the expansion of knowledge about masonry laying mortar, especially regarding the dosing process, the influence of the constituents in this cementitious composite, and the correlations and interdependencies that exist between these properties.
We concluded that the proposed method is efficient and achieves good quality mortar for use in structural masonry laying purposes while considering different environmental conditions.The proposed innovations, which are the means of acquiring the contents of each component and the adequate mixtures through approximation curves developed via spreadsheets, were adequate for use in factories, laboratories, and work sites.

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Table 1 .
The binder content for different performance

Table 3 .
Structural masonry laying mortar proportions

Table 4 .
Compression (f c ) and flexural (f t ) strength results