Why use polyurethane sealant to caulk concrete?

Due to factors such as dry shrinkage and thermal expansion and cold shrinkage of materials, in the construction process, concrete materials need to set a large number of construction joints and cutting joints, etc., and the treatment of these joints will greatly affect the use and life expectancy of the project.

So, what about the concrete joints all around us? It can be found that more than 70% of the joints have different degrees of problems, mainly the following four categories......

1. Degumming - poor bonding with concrete, colloidal shedding, edge collapse

2. Foreign body embedding - the sealant strength is not enough, resulting in stone and other foreign body piercing sealant

3. Inelastic - After the sealant shrinks or ages, the hardness increases, the elasticity is lost, and the displacement cannot be compensated

4. Shrinkage cracking - the sealant contains solvents or plasticizers, and after the solvent volatilizes, the sealing colloidal product shrinks and cracks

The sealant used with concrete joints should have the following three basic requirements:

1. It has excellent adhesion with concrete materials, and can still maintain adhesion even in harsh long-term water environment

2. Durable elasticity can compensate the displacement and deformation caused by dry shrinkage, settlement and thermal expansion and cold contraction of concrete materials

3. Excellent physical strength to resist the friction and embedding of foreign bodies such as tires and stones

Polyurethane sealant and concrete materials have excellent adhesion, whether for dry concrete joints, wet concrete joints, newly cured concrete joints or long-term soaked concrete joints, through the correct surface treatment, can obtain satisfactory bonding effect. In some concrete joints in sewage treatment plants, DAMS and canals, it is inevitable that they will need to be used for a long time in a submerged environment. Concrete is a porous alkaline base material, which will absorb water and produce chemical reactions in a long-term soaking environment, leading to problems such as return alkali.As a result, sealing of joints under prolonged immersion in water is considered a demanding challenge. After proper surface treatment of concrete joints, polyurethane sealant can obtain good adhesion and meet application requirements.

Polyurethane sealant not only has excellent adhesion with concrete materials, but also has different displacement levels to meet the requirements of different joint widths and different joint designs.

Polyurethane sealant has different modulus choices of high modulus and low modulus to meet the requirements of concrete interfaces of different strengths, in order to reduce the interface damage caused by the influence of stress on the concrete interface.

In the process of using concrete materials on the ground, it will face more risks such as friction and puncture from vehicle tires, sweeper brush, high heels and gravel.Polyurethane sealant has a high tear strength, even after strong external damage, the crack will not expand quickly, avoiding the overall damage.