Mechanical Degradation and Thermal Decomposition of Ethylene-Vinyl Acetate (EVA) Polymer-Modified Cement Mortar (PCM) Exposed to High-Temperature

Abstract

A polymer-modified cement mortar (PCM) is widely used as a repair material for reinforced concrete (RC) structures owing to its excellent strength and durability. However, considering the maintenance of the RC structures and the use period of the structures, the change in the physical properties of the PCM should be evaluated when exposed to various high-temperature environments, such as fires. In this study, the degradation of the mechanical properties (compressive strength and modulus of elasticity), thermal decomposition of the PCM in various high-temperature environments, and the change in the pore structure of the PCM after exposure to high temperatures were quantitatively investigated. A mechanical property evaluation of PCM was performed under three heating conditions: (i) heating in a compression tester, (ii) heating the specimen in an oven to a predetermined temperature and then moving it to a compression tester preheated to the same temperature, and (iii) cooling to room temperature after heating. In the experiment, a PCM specimen was prepared by changing the polymer–cement ratio (polymer content) of ethylene-vinyl acetate (EVA), the most commonly used polymer, to perform a high-temperature sectional test from 200 to 800 °C. In addition, to investigate the change in the PCM mechanical properties in the high-temperature region, in terms of the pyrolysis of EVA, the porosity change and mass change were examined using thermal analysis and mercury intrusion porosimetry. Before heating, the compressive strength of the PCM increased with the EVA content up to 10 % of the polymer–cement ratio. Under the cooling conditions after heating up to 200 °C, the mechanical performance of the PCM was restored, whereas the degradation of the mechanical properties of the PCM without cooling was more pronounced. Furthermore, the mass loss, heat flow, and the total porosity of the PCM increased as the EVA content increased, which is correlated with the degradation of the mechanical properties of the PCM.

Effectiveness of metakaolin and hybrid polymers incorporated mortar for the compressive strength and acid resistance of industrial and wastewater infrastructure

“…The flow table value was increased by 34.7% and 24.6%, respectively, when EVA and PVA replaced 5% of cement. The flow table value was increased by 15.4% when 2.5% of each polymer was used (Results are in agreement with the recent researches by Kim et al 201931 Yang et al 202019 . Polymers might entrain some air.…”

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

“…Such behavior justifies the use indicated in the bibliography [6], [21], [22], [35], demonstrating performance also as a plasticizer, increasing the consistency. It is noticed that this admixture acts through the entanglement of polymeric molecules, which in high concentrations, and suffering the stresses of the spreading table, fluidized the material [37], explaining the increase in the spreading diameter with the higher dosage of the admixture.…”

“…Its main activities are in improving adhesion, flexural strength, deformability, abrasion resistance, maximizing its use in adhesive mortars, grouts and plasterboards glues. However, studies [21], [22] showed the potential of this admixture for use as water retainer.…”

“…These three admixtures are marketed as water retainers, however, though previous research [9], [10] it was identified that some did not have enough retention. It is also important to note that the dosages are variable in the research [2], [5]- [8], [13], [18], [21], [22], and because of this it can generate different influences on mortars. Therefore, it was decided to carry out this research to investigate the dosage and efficiency of each admixture exposed.…”

The Influence of a Polymer Powder on the Properties of a Cold-Recycled Mixture with Foamed Bitumen

“…Various forms and types of polymers are used both to modify cement concrete mixtures and to produce polymer-cement concretes (PCC), polymer-impregnated concretes (PIC) and polymer concretes (PC) [20]. In [21], Kim et al presented an application of EVA polymer to the production of polymer-modified cement mortar (PCM), a widely used repair material for reinforced concrete (RC) structures due to its excellent strength and durability. Successful testing of the addition of polymers to cement concrete was described by Gutarowska et al [22] and Shen et al [23].…”