Spraying quick-setting rubber asphalt waterproof coating is a water-based coating. If the diaphragm is not fully maintained after spraying, the water will not completely evaporate, and dense air bubbles will easily appear during high-temperature baking, resulting in thinning of the waterproof film, and poor waterproof, anti-corrosion, and weather resistance. . Because the maintenance environment conditions on the construction site are usually uncontrollable, it is imperative to improve the high temperature resistance of sprayed quick-setting rubber asphalt waterproof coatings from the perspective of formulation.
Water-soluble cellulose ether was selected to improve the high temperature resistance of sprayed quick-setting rubber asphalt waterproofing materials. At the same time, the effects of the type and amount of cellulose ether on the mechanical properties, spraying performance, heat resistance and storage of spraying quick-setting rubber asphalt waterproof coatings were studied. performance impact.
Sample preparation
Dissolve hydroxyethyl cellulose in 1/2 deionized water, stir until it is completely dissolved, then add emulsifier and sodium hydroxide to the remaining 1/2 deionized water and stir evenly to prepare a soap solution, and finally, mix the above The two solutions are evenly mixed to obtain an aqueous solution of hydroxyethyl cellulose, and its pH value is controlled between 11 and 13.
Mix emulsified asphalt, neoprene latex, hydroxyethyl cellulose aqueous solution, defoamer, etc. according to a certain ratio to obtain material A.
Prepare a certain concentration of Ca(NO3)2 aqueous solution as B material.
Use special electric spraying equipment to spray material A and material B onto the release paper at the same time, so that the two materials can be contacted and quickly set into a film during the cross atomization process.
Results and discussion
Hydroxyethyl cellulose with a viscosity of 10 000 mPa·s and 50 000 mPa·s was selected, and the method of post-addition was adopted to study the effects of the viscosity and addition amount of hydroxyethyl cellulose on the spraying performance of quick-setting rubber asphalt waterproof coatings, Film-forming properties, heat resistance, mechanical properties and storage properties. In order to avoid the damage to the system balance caused by the addition of the hydroxyethyl cellulose solution, resulting in demulsification, an emulsifier and a pH regulator were added during the preparation of the hydroxyethyl cellulose solution.
Influence of Viscosity of Hydroxyethyl Cellulose (HEC) on Spraying and Film-forming Properties of Waterproof Coatings
The greater the viscosity of hydroxyethyl cellulose (HEC), the greater the impact on the spraying and film-forming properties of waterproof coatings. When its addition amount is 1‰, HEC with a viscosity of 50 000 mPa·s makes the viscosity of the waterproof coating system When it is increased by 10 times, spraying becomes very difficult, and the diaphragm shrinks severely, while HEC with a viscosity of 10 000 mPa·s has little effect on spraying, and the diaphragm shrinks basically normal.
Effect of Hydroxyethyl Cellulose (HEC) on Heat Resistance of Waterproof Coatings
The sprayed quick-setting rubber asphalt waterproof coating was sprayed on the aluminum sheet to prepare the heat resistance test sample, and it was cured according to the curing conditions of the water-based asphalt waterproof coating stipulated in the national standard GB/T 16777-2008. The hydroxyethyl cellulose with a viscosity of 50 000 mPa·s has a relatively large molecular weight. In addition to delaying water evaporation, it also has a certain strengthening effect, making it difficult for water to evaporate from the interior of the coating, so it will produce larger bulges. The molecular weight of hydroxyethyl cellulose with a viscosity of 10 000 mPa·s is small, which has little effect on the strength of the material and does not affect the volatilization of water, so there is no bubble generation.
The effect of the amount of hydroxyethyl cellulose (HEC) added
Hydroxyethyl cellulose (HEC) with a viscosity of 10 000 mPa·s was selected as the research object, and the effects of different additions of HEC on the spraying performance and heat resistance of waterproof coatings were investigated. Considering the spraying performance, heat resistance and mechanical properties of waterproof coatings comprehensively, it is considered that the optimal addition amount of hydroxyethyl cellulose is 1‰.
The neoprene latex in the sprayed quick-setting rubber asphalt waterproof coating and the emulsified asphalt have a large difference in polarity and density, which leads to delamination of material A in a short period of time during storage. Therefore, during on-site construction It needs to be stirred evenly before it can be sprayed, otherwise it will easily lead to quality accidents. Hydroxyethyl cellulose can effectively solve the delamination problem of sprayed quick-setting rubber asphalt waterproof coatings. After one month of storage, there is still no delamination. The viscosity of the system does not change much, and the stability is good.
focus
1) After hydroxyethyl cellulose is added to the sprayed quick-setting rubber asphalt waterproof coating, the heat resistance of the waterproof coating is greatly improved, and the problem of dense bubbles on the surface of the coating is greatly improved.
2) Under the premise of not affecting the spraying process, film-forming performance and material mechanical properties, the hydroxyethyl cellulose was determined to be hydroxyethyl cellulose with a viscosity of 10 000 mPa·s, and the addition amount was 1‰.
3) The addition of hydroxyethyl cellulose improves the storage stability of the sprayed quick-setting rubber asphalt waterproof coating, and no delamination occurs after storage for one month.
Post time: May-29-2023