The purpose of the filler plus filler is to increase the strength of the epoxy mortar, improve the aging performance, reduce the shrinkage rate and the exothermic reaction during the hardening process and reduce the cost. Medium-sized river sand, diabase powder and cement are generally available. The mix ratio of the mix ratio can be adjusted within a certain range according to the atmospheric temperature and the urgent need of the project. The temperature in summer is high, the ethylenediamine should be less appropriate, and the sand should be more appropriate; if the temperature is low in winter, it should be reversed. The modulation mix ratio must be guaranteed not to harden within 1h to meet operational requirements.
According to the practice of many years, the mix ratio of winter and summer can be referred to. Epoxy mortar mix ratio material name specification summer winter epoxy resin butyl butyl ether diamine sand 6101 (E-44) chemical pure medium sand, 0.25mm â‰¤ particle size â‰¤ 0.5mm water content â‰¤ 0.2% mix ratio Weight calculation; 2 the highest temperature in summer is 30 Â°C, the lowest in winter is -10 Â°C, other temperatures can be adjusted according to the actual situation.
The main factors affecting the strength of epoxy mortar (1) the amount and quality of ethylenediamine directly affect the strength and adhesion of epoxy mortar, epoxy resin itself will not harden, just add the right amount of ethylenediamine to gradually harden, The amount of ethylenediamine should be strictly in accordance with the mixing ratio. Because the dosage is not much, the reaction is very sensitive, slightly more, and the explosion will occur in a dozen or more minutes when the summer temperature is high.
(2) The moisture content of the sand has a great influence on the strength of the epoxy mortar. When the water content of the sand is large, a water film is formed on the surface of the sand to reduce the adhesion. Therefore, it must be dried to make the water content â‰¤ 0.2. %.
(3) The porosity of epoxy mortar has an effect on strength and cohesive force. The more pores, the lower the tensile and compressive strength. At room temperature, the epoxy resin contains a large number of bubbles, which is the main factor affecting the porosity. Therefore, before use, the epoxy resin should be heated to 80 Â° C to discharge air bubbles, and avoid introducing air during the mixing process.
(4) The surface of the bonded object is required to be clean and clean. The reason why the epoxy mortar has strong adhesion to the bonded object (steel, concrete) is because the active atomic group and the adherend in the epoxy resin The polarity attraction between the surface molecules, if the surface of the bond is oily, rust and other dirt, will affect the adhesion, and must be cleaned.
(5) In addition to river sand, diabase powder and cement can also be used, but the particle size and water content should meet the requirements of river sand. After use, the strength of the two materials is slightly higher than that of river sand, but the cost is also high. The latter two fillers are rarely used in construction. Temperature has a great influence on the growth of epoxy mortar. In general, the temperature is high and the strength increases rapidly; the temperature is low and the strength is relatively slow; especially after the temperature reaches zero, the strength grows more slowly.
The strength of the epoxy mortar at +20 Â° C. The main physical and mechanical properties of epoxy mortar are tensile strength of 15-20 MPa; compressive strength is 70-90 MPa; compression modulus is (0.7-1.5)Ã—104 MPa; bulk density is 1.7-1.8 g/cm3.
Construction procedure (1) New foundation for bonding anchor bolts with epoxy mortar Before casting concrete, the steel bars at the position where the bolts are located must be removed by more than 80 mm. Otherwise, it is difficult to handle the steel bars when they are formed into holes. (2) According to the drawings, lay the line on the newly built foundation or the old foundation that has been constructed, and determine the center position of the bolt. (3) When the new foundation machinery is formed into a hole, it is necessary to wait until the concrete reaches a certain strength to start. The strength is too low, the hole wall is easily broken during drilling, which affects the bonding quality; if the concrete strength is too high, the drilling is difficult. Practical experience shows that the best time to make holes is when the concrete strength reaches 70-100. This strength can be inferred according to the cement type and atmospheric temperature, concrete strength curve, and can also be measured by the rebound tester.
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