Influence of waterborne epoxy mortar on waterborne epoxy protective system

introduction

Modern buildings mostly use reinforced concrete walls, which are constructed by pouring concrete.

With the continuous improvement of people's demand for the appearance of concrete structures, the need for decoration of concrete structures with surface defects has become more urgent.

The walls of some large-scale civil works in our country are constructed by pouring concrete, resulting in a large number of defects on the surface of the wall.

Test Results and Discussion

1 Influence of Portland cement grade on system performance

Portland cement has excellent properties such as fast setting and hardening, good frost resistance, good wear resistance and low cost, which makes it an indispensable main material in any building construction

Fix the components A and B of the water-based epoxy mortar, change the label of the Portland cement in the component C, and select the Portland cement 325, 425, 525 and 625 for testing, and the coating thickness of the fixed water-based epoxy mortar is 1 ~2mm, study the effect of different grades of Portland cement on the adhesion of the system, the results are shown in Table 1

Table 1 The effect of different grades of Portland cement on the adhesion of the system

From Table 1, it can be found that with the increase of the Portland cement grade, the adhesion of the coating system increases significantly; the adhesion test results of the coating system using 525 and 625 cement are similar, which is related to the strength of the substrate , the substrate was damaged to some extent

2 Influence of the amount of water-based epoxy resin on the performance of the system

Water-based epoxy mortar is mainly composed of two parts, resin and cement.
The two are used together to complement each other, so that the performance of water-based epoxy mortar is optimal
.
The effect of the sum of the dosage of components A and B on the adhesion performance of the system was investigated in the experiment, and 525 Portland cement was selected in the experiment.
The results are shown in Table 2
.

Table 2 The effect of the sum of the amounts of different components A and B on the adhesion of the system

It can be found from Table 2 that with the increase of the resin content, the adhesion of the system increases significantly.
After the sum of the dosages of components A and B reaches 25% of the component C, the adhesion of the system increases slowly.
At this time, by increasing the resin content, the strength of the resin in the system is continuously improving.
However, due to the decrease in the proportion of cement, the contribution of the strength of the cement itself to the overall strength of the system is getting smaller and smaller, resulting in a slower increase in the adhesion of the system
.

Considering the material properties and economy, an amount of the components A and B, and optimal component is 25% ~ 40% C in
.

3 Influence of quartz sand particle size on system performance

The components A and B of the water-based epoxy mortar were fixed, and the water-based epoxy mortar was prepared by using quartz sand with different mesh numbers in the component C.
The coating thickness was 5~6mm.
The effect of anti-cracking performance is shown in Figure 2
.

Fig.
2 The effect of quartz sand on the cracking resistance of water-based epoxy mortar

It can be seen from Figure 2 that the thickness of quartz sand has a significant impact on the anti-cracking performance of water-based epoxy mortar
.

4 Influence of waterborne epoxy mortar thickness on system performance

In the process of practical application, when water-based epoxy mortar repairs large defects such as staggered surfaces on the concrete surface, the water-based epoxy mortar may be constructed too thick at one time, and the water-based epoxy mortar may crack during the drying and curing process.
Effects of waterborne epoxy mortars of different thicknesses on system adhesion
.

Select 525 Portland cement and 80-120 mesh quartz sand to prepare component C, construct water-based epoxy mortar of different thicknesses, and investigate the anti-cracking performance, as shown in Figure 3
.
After matching the water-based epoxy putty and the water-based epoxy topcoat, the adhesion of the system was investigated.
The results are shown in Table 3
.

Fig.
3 Cracking situation of water-based epoxy mortar with different construction thickness

Table 3 Influence of different construction thickness on system adhesion

It can be seen from Figure 3 that as the construction thickness of the water-based epoxy mortar is thicker, the cracks on the surface of the mortar are more obvious; when the construction thickness of the water-based epoxy mortar reaches 3~4mm, obvious cracks can be seen on the surface of the mortar.
The more obvious the crack, when the construction thickness reaches 7~8mm, the width of the crack reaches 1mm
.

As for the adhesion of the system, it can be seen from Table 3 that when the construction thickness of the water-based epoxy mortar reaches more than 1mm, the adhesion of the system basically remains above 2Mpa.
With the increase of the construction thickness, the adhesion does not change much.
They are all water-based epoxy mortar layers with part of the substrate; the water-based epoxy mortar is too thin to exert the strength of cement, but leads to the low strength of the mortar layer
.

It can be seen that the optimal construction thickness of water-based epoxy mortar is between 1 and 3 mm
.

Epilogue

The effects of different grades of cement, the dosage of water-based epoxy resin, the particle size of quartz sand and the construction thickness of cement mortar on the performance of the water-based epoxy protection system were investigated, and the water-based cement mortar with excellent performance was prepared:

(1) Comparing the influence of different grades of cement on the strength of water-based epoxy mortar, the experiment found that using high-grade cement, the strength of the material is the best, considering the material properties and economy, 525 cement is used;

(2) When the sum of the dosage of waterborne epoxy mortar components A and B is 25%~40% of component C, the comprehensive performance of the waterborne epoxy protection system is optimal;

(3) The use of coarse sand is more significant for the anti-cracking performance of the system;

(4) By examining the construction thickness of water-based epoxy mortar, it is found that the optimal construction thickness of water-based epoxy mortar is between 1 and 3 mm
.

References (omitted)

Author | Li Peng, Liu Zhiyuan, Zhang Rui, et al

(CNOOC Changzhou Coating Chemical Research Institute Co.
, Ltd.
)