Natural rubber latex is the white liquid in the form of the colloidal dispersion of rubber globules suspended in the aqueous liquid. Produced in large quantities in Ivory Coast, the local transformation of natural latex has so far remained insignificant, although some attempts have been made to use it in the manufacture of flexible facade briquettes for rounded walls. Thus, this study aims to incorporate clay as a filler in natural latex for use as an adhesive for tile installation. To do this, different proportions of clay paste were added to the natural latex and the resulting mixtures were used to make the sample and tile adhesive. From the analysis of the results obtained, it appears that the samples with a clay paste density of 0.8 and 1 absorb less water and show s good pull-out strength. The mixtu res of 30% and 35% latex and 0.8 and 1 clay paste density respectively have pullout stresses greater than 1 N/mm2. According to NF EN 1348, these adhesives can therefore be used as tile adhesive.
Cote d’Ivoire produces 60% of Africa’s rubber, making it the largest rubber producer in Africa and the seventh largest (7th) producer in the world. It reached 800,000 tonnes in 2018 compared to 603,000 tonnes in 2017 and 468,000 in 2016 [
These are cement mortars, lime mortars, cement-lime mortars, earth mortars and adhesive mortars. The last group, adhesive mortars are in powder form (bag- ged) composed of one or more hydraulic binders (cement), organic (resin, latex), mineral fillers (sand, etc.), admixtures and they are used for tiling walls and floors (interior and or exterior). Latex is now widely used in industrial formulations where it is valued for its adhesion properties in various fields such as paint, paper, adhesive and the cement industry [
· Sablatex (sand-latex) for facades of rounded walls [
· Briquettes made from natural latex and laterite [
Thus, this study is carried out with the aim of making an adhesive without cement and without synthetic latex, in other words by substituting it with natural rubber latex. In fact, natural rubber latex in its liquid form is little used because in the space of a day it coagulates so its storage is problematic. In contrast, this work aims to propose a method of using this liquid latex for the production of fluid adhesive that can be stored over a long period (at least one year) before this coagulation occurs.
The rubber latex used for making the adhesive tiles comes from a private rubber plantation located in the municipality of Dabou (Côte d’Ivoire). It is used in its liquid form for making samples. After sampling, an ammonia solution is added to it in order to keep it in the liquid state and send it to the laboratory for being looked into.
The clay used is extracted on the site of Dabou. The samples collected are dried for two weeks and then reduced into pieces of about two centimeters with a jaw crusher before being crushed in a ball mill. The powder obtained is pass- ed through a 1 mm sieve. It is the passerby thus collected that serves as the basic raw material for this study. This clay is clayey silt composed mainly of kaolinite.
Liquid latex contains particles of monomers dispersed in an aqueous phase (serum).
As it coagulates, the monomer particles clump together forming a glue that binds the elements together. These processes rely on this ability of natural latex to bind together for use as a tile adhesive. Liquid latex has very low viscosity. It flows easily. Also to give it smoothness, a mineral filler has been added. The mineral filler used is clay. Clay was used because it has a low specific surface and its surface is negatively charged (kaolinite), what allows them to bond with resins and polymers. Two processes were used to develop tile adhesive based on natural rubber latex.
· First process: liquid latex plus mineral filler as a tile adhesive.
This first process is summarized in
· Second process: liquid latex plus slip (clay + water) as tile adhesive.
Clay has a water absorption capacity that should be taken into account. To account for this fact, a clay slip was used as a filler in this process. A water/clay ratio was defined (0.2; 0.4; 0.6; 0.8; 1). For each ratio, the added latex content varies from 20%, 23% and 26%.
give the slip. Latex is added to the slip obtained. Then, the whole is kneaded again for 25 seconds so as to obtain a visibly homogeneous paste. It is the slip- latex glue that is worn in the molds.
Naturally, liquid latex behaves like a glue that can be used to bind things together. However, this glue is too fluid to be used as a mortar. Also, different proportions of clay were added as fillers. This adhesive must have sufficient fluidity to perform this function of binder. This is why the first latex content was taken at 16% with 84% clay which corresponds to the least fluid dough possible. In addition, to limit the amount of latex and increase the fluidity of the different mixtures, different amounts of water were added to the mixture. These different formulations used for the design of the different adhesives are presented in
Water absorption (Abs) is the capacity of certain materials to absorb water in the liquid state [
Username | Latex (%) LA | Clay (%) Ar | Water/clay E/Ar |
---|---|---|---|
ArLA16 | 16 | 84 | - |
ArLA23 | 23 | 77 | - |
ArLA28 | 28 | 72 | - |
ArLA33 | 33 | 67 | - |
ArLA37 | 37 | 63 | - |
ArLA44 | 44 | 56 | - |
ArLA50 | 50 | 50 | - |
ArLAE20-0,2 | 20 | 80 | 0.2 |
ArLAE23-0,2 | 23 | 77 | |
ArLAE26-0,2 | 26 | 74 | |
ArLAE20-0.4 | 20 | 80 | 0.4 |
ArLAE23-0.4 | 23 | 77 | |
ArLAE26-0.4 | 26 | 74 | |
ArLAE20-0.6 | 20 | 80 | 0.6 |
ArLAE23-0.6 | 23 | 77 | |
ArLAE26-0.6 | 26 | 74 | |
ArLA20-0.8 | 20 | 80 | 0.8 |
ArLAE23-0.8 | 23 | 77 | |
ArLAE26-0.8 | 26 | 74 | |
ArLAE20-1 | 20 | 80 | 1 |
ArLAE23-1 | 23 | 77 | |
ArLAE26-1 | 26 | 74 |
ArLA = clay + latex, ArLAE = clay + latex (NR) + water.
A b s ( % ) = m H − m S m S × 100 (1)
with: Abs: water absorption;
mH: wet mass (g);
mS: dry mass (g).
The adhesion test measured according to EN 1348 is a test carried out to determine the ability of the mortar to adhere correctly to the substrates to which it is applied. Adhesion is measured by evaluating the minimum tensile stress required to loosen or break the coating perpendicular to the substrate. The adhesion strength corresponds to the value read on the traction device (
For masonry work, the glue (binder) used to build the masonry units must be neither too fluid so that it does not flow outside the partitions nor too rigid for its handling to be easy. Therefore, it is necessary to find the right design process. To find the right compromise between fluidity and consistency of the fresh glue from natural latex, on the one hand their workability and homogeneity were analyzed and on the other hand their appreciated hardness.
Mixed | Appearance of mixtures | Image | |
---|---|---|---|
Process 1 | clay + Latex | Training lumps | |
Process 2 | (clay + water) + Latex | Homogeneous paste visibly |
the formation of lumps. The presence of lumps in the glue is a defect. This method 1 cannot therefore be used. Similar results were obtained by [
This absorption of materials leads to many damages. The results of the immersion absorption test performed are shown in
dispersion of polymer particles is transformed into continuous material) [
Mechanical properties are the most sought-after parameters of mortars. To assess them, the various mortars were subjected to pull-out tests.
The tile adhesive used in laying traditional tiles is applied between the tiles and the substrate to which the tiles are to be bonded. It thus ensures adhesion between the two elements. So adhesion seems to be the essential criterion for the use of an adhesive in the laying of tiles. Also, all the glues produced were subjected to the adhesion test. According to the results, after (28 days) of drying (
This poor adhesion of ArLAE0.2, ArLAE0.4 and ArLAE0.6 glues is due to the fact that there is no reaction between the latex and the various supports. The adhesion of the various adhesives to the substrate and to the tiles is certainly ensured by the anchoring of the latex in the roughness and voids on the surface of the substrate and the tile. In order for the glue to penetrate these different surface rough- ness, it must first be wet. Thus, for water/clay ratios of 0.2, 0.4 and 0.6, the lack of adhesion is linked to the fact that the glues are too dry: their workability is very firm to firm; the presence of clay makes it difficult to flow. The liquid fraction contained in the glue cannot sufficiently soak the surface of the support. This is therefore not moistened enough to allow adhesion between the two materials. With all other glues prepared, the bond strength was determined because these contain sufficient water and have workability which is either normal or fluid. The variations in pullout stresses (adhesion) observed are explained by the increase in the amount of latex and the existence of microcracks in the dry glue due to drying shrinkage. Indeed, when the amount of latex increases in the glue, the anchoring points of the rubber monomers in the various supports multiply, hence the increase in the adhesion force.
[
According to standard EN NF 1348, an adhesive mortar which has good adhesion and which must be used for tiling work must have a pull-out stress (traction adhesion) greater than or equal to 1 N/mm2. Below this value, this standard
considers adhesive mortars as having poor adhesion. The adhesives ArLAE26-1 and ArLAE26-0.8 have good adhesion because they have pull-out stresses greater than 1 N/mm2 from 18% latex content. ArLAE1 adhesives with 30 % latex content have good adhesion because the pull-out stress obtained is 2.6 N/mm². Similarly, ArLAE26-1 and ArLAE26-0.8 adhesives have peel strength of over 1 N/mm².
The homogeneity of the mixtures made it possible to choose a process for developing glues based on natural rubber latex. The different mixtures produced exhibited different homogeneities. The clay-latex mixture gives a non-homoge- neous paste with the formation of lumps and the clay-latex-water mixture is a homogeneous mixture. The clay-latex mixture was therefore given up because of its poor homogeneity. ArLA0.8 and ArLAE1 adhesives absorb less water than other manufactured adhesives. The pull-out test showed that the adhesives ArLAE0.2, ArLAE0.4, ArLAE0.6 have poor adhesion with the tiles, the support and the adhesives ArLAE23-0.8, ArLAE20-1 and ArLAE23-1 have pull-out strength of less than 1 N/mm2. ArLAE26-0.8 and ArLAE26-1 give better results and can be used as tile adhesive. However, when the thickness of the bonding mortar is large, this mortar has practically no rigidity. Therefore, it should be considered to increase its stiffness by adding granular material.
The authors declare no conflicts of interest regarding the publication of this paper.
Ohouo, D.H., Kouakou, C.H., Boffoue, M.O., Eméruwa, E. and Traoré, B. (2022) Incorporation of Clay into Natural Rubber (Hevea) for the Production of Tile Adhesive. Open Journal of Composite Materials, 12, 30-40. https://doi.org/10.4236/ojcm.2022.121003