It is required that the deviation between the center of the bolt group and the positioning axis does not exceed 100 mm, the deviation of the center distance between adjacent bolt groups should not be more than 100 mm, and the cumulative error of the center distance along the coaxial line must remain within 100 mm. Additionally, the positive error for all bolt elevations should not exceed 3900 mm. The construction period is scheduled for June and July, when the average outdoor temperature is around 12°C. In this context, angle steel is used as the primary material.
To ensure precision and stability, a one-time pouring forming method using angle steel molds is implemented. This approach helps maintain alignment and structural integrity during concrete pouring. Given the high pre-buried quality requirements, large column section sizes (typically ranging from 312200 to 332200 mm), and the use of large-diameter and long-length bolts, the mold must have sufficient rigidity and be convenient for concrete placement. As a result, a two-layer mold system is designed. The threaded portion of the bolts is extended appropriately, and each bolt is fixed at the lower part of the lower frame and the upper part of the upper frame during installation. Different types of angle steel are selected based on the bolt specifications to ensure proper hole diameter and mold rigidity.
The connection between the mold and the short column formwork, as well as the top ring beam ribbing, is carefully considered. During the preparation of the short column formwork, a wooden formwork of at least 92200 mm is installed at the top, while the lower part uses combined steel formwork. This combination ensures both strength and flexibility.
Before construction begins, the site is leveled, and a gantry wall is built at the designated axis position. The surface is smoothed with mortar and leveled accordingly. The specifications and quantities of the bolts are determined in advance. Based on the column section size and height, the number of templates for each specification is planned. A total station (with automatic temperature correction) is used to set up the vertical and horizontal axes on the gantry wall. A level instrument is then used to transfer elevation control lines to the four corners of the gantry wall, serving as a reference for controlling the height of the column and the embedded bolts.
Molds are fabricated according to different bolt diameters. For example, B14, B7C, and B42 pre-embedded bolts are used, with the corresponding apertures slightly larger than the bolt diameter. The error between adjacent holes is kept within 25 mm, and the diagonal error is limited to 300 mm. The upper and lower molds are connected using bolts, and the axis positions are uniformly marked. Holes are punched using a drilling machine to ensure concentricity and uniform size across the same mold. To facilitate the connection with the short-column template, the lower mold is formed, and the upper and lower parts are spaced 3200 mm apart, connected by a connecting member.
During construction, the release line is established based on the control network on the gantry wall. A theodolite is used to mark the axis on the concrete surface of the column, and the column frame line is projected. If any displacement of the column reinforcement is detected, it is corrected immediately. At the bottom of the column template, the height of the embedded bolt is controlled with a positive error less than 3900 mm. To achieve this, a 3D1 cement mortar leveling layer is applied, with a thickness not exceeding 9200 mm.
Given the large cross-section of the short column (the longest side being 3510 mm and the shortest side 3590 mm), pull-through screws are used for the formwork, with spacing calculated based on structural requirements. After the steel formwork support is reinforced, bamboo-glued formwork is installed and bolted to the steel formwork. Using the established control network, the vertical and horizontal axes are measured onto the wooden formwork keel. The mold is mounted on the wooden formwork, secured with bolts, and the embedded bolts are inserted into the mold, fixed with nuts at both ends. Due to the long length of the bolts, concrete is poured evenly around the periphery of the column to prevent displacement. Vibration points are distributed evenly to avoid damaging the bolts or formwork. A tarpaulin is placed over the bolts after they are fixed to protect them from contamination or damage during pouring.
Vibrating the rebar directly against the formwork, bolts, or anchors is strictly prohibited. Following this method, the steel frame column and beam are installed in one go, without reaming, which saves costs and simplifies the production process.
Low Porosity Refractory Brick
Low porosity clay bricks are made of low aluminum mullite as the main raw material, formed by high pressure molding and high temperature sintering. The main mineral composition is mullite phase, the product has excellent high temperature physical properties and chemical erosion resistance.
Low porosity clay brick stability is good, the degree of erosion does not occur sudden change, than ordinary clay brick life increased by 2 to 3 times. Thermal conductivity, specific heat and solubility, respectively, than ordinary clay bricks 2 times higher than 10% and 40%, heat storage capacity than ordinary clay bricks 50% to 60% higher than the thermal efficiency of the kiln can be improved.
Low porosity clay bricks are characterized by:
1. Low porosity, 13 to 15%;
2. Load softening temperature is high for about 1472 ℃;
3. High compressive strength at room temperature, generally about 100MPa;
4. Good volume stability at high temperature and good abrasion resistance;
5. good resistance to infiltration and erosion.
Low porosity clay brick as a good clay refractory brick products, so often used in chemical erosion, temperature fluctuations in the environment, such as steel, glass, chemical industry. The effect is quite obvious in the use of glass hot room and the use of iron water tank.
Suitable for Plugging Oven Holes,Clogging Refractory Clay Bricks,Clogging Refractory Clay Brick
Huixian Xinwei Refractories Co. , https://www.xinweirefractory.com