Analysis of the function of the bolt body of the oxidized paddle frame

The purpose of adding fillers to epoxy mortar is to enhance its mechanical strength, improve resistance to aging, reduce shrinkage during curing, minimize the exothermic reaction, and lower overall costs. Commonly used fillers include medium-sized river sand, diabase powder, and cement, which are readily available. The mix ratio can be adjusted depending on ambient temperature and project urgency. In summer, when temperatures are higher, it's advisable to use less ethylenediamine and more sand, while in winter, the opposite applies. It's crucial that the mixture doesn't set within one hour to ensure proper handling and application. Based on years of practical experience, typical mix ratios for summer and winter can be referenced. For example, in summer, when temperatures reach up to 30°C, the mix may consist of epoxy resin (E-44), butyl butyl ether, ethylenediamine, and medium sand with a particle size between 0.25mm and 0.5mm and moisture content below 0.2%. Winter mixes would adjust these proportions accordingly. Several factors influence the strength of epoxy mortar. First, the quantity and quality of ethylenediamine directly impact the mortar’s strength and adhesion. Epoxy resin alone does not harden without the correct amount of amine curing agent. The dosage must be strictly followed, as even small variations can lead to rapid or excessive reactions, especially in warm weather. Second, the moisture content of the sand significantly affects performance. High moisture can create a water film on the sand surface, reducing adhesion. Therefore, the sand must be dried thoroughly to maintain moisture levels below 0.2%. Third, the porosity of the mortar also plays a role in its strength. More pores mean lower tensile and compressive strength. At room temperature, epoxy resin often contains bubbles, which contribute to porosity. To reduce this, the resin should be heated to 80°C before use to remove air bubbles, and care must be taken during mixing to avoid introducing new air. Fourth, the surface of the bonded object must be clean and free of contaminants like oil or rust. Epoxy mortar adheres well due to molecular polarity interactions between the resin and the surface. Any dirt can weaken the bond, so thorough cleaning is essential. Lastly, while river sand is commonly used, alternatives like diabase powder and cement can also be employed. These materials offer slightly better strength but at a higher cost, making them less common in construction. Temperature greatly affects the curing process—higher temperatures speed up strength gain, while lower temperatures slow it down, especially once freezing occurs. At +20°C, the physical and mechanical properties of epoxy mortar typically include a tensile strength of 15–20 MPa, compressive strength of 70–90 MPa, a compression modulus of (0.7–1.5)×10⁴ MPa, and a bulk density of 1.7–1.8 g/cm³. For construction procedures, when bonding anchor bolts using epoxy mortar, it's important to remove steel bars at least 80 mm away from the bolt location before pouring concrete. This prevents difficulties during hole formation. Once the foundation is ready, lines should be marked according to the design, and the bolt center position determined. When drilling holes in a new foundation, wait until the concrete reaches a suitable strength—ideally 70–100% of its final strength. This ensures the hole walls remain intact during drilling. Practical experience suggests that using a rebound hammer or referring to strength curves based on cement type and temperature helps determine the right time for drilling.

Safety Washer DIN 9250VS

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