If grout leakage occurs during concrete pouring, it not only leads to quality defects such as honeycomb and pitting on the concrete surface, but also reduces the strength and durability of the components, increasing later repair costs. To reduce grout leakage, improvements are needed in multiple dimensions, including formwork selection, joint treatment, root sealing, support system, concrete mix proportions, vibration technology, and construction management, forming a systematic solution.
Formwork selection is fundamental to reducing grout leakage. Traditional wooden formwork is prone to deformation and warping due to frequent reuse, and joints are difficult to seal tightly. It is recommended to prioritize high-strength, high-rigidity plywood or steel formwork to reduce the number of joints. Larger formwork sizes can reduce splicing frequency, while standardized production of steel formwork ensures dimensional accuracy, reducing gaps from the source. Before use, the surface of the formwork must be thoroughly cleaned of concrete residue and oil stains, and a water-based or oil-based release agent should be applied evenly, avoiding accumulation or missed application of the release agent to prevent concrete from adhering to the formwork, which could lead to difficulties in demolding or grout leakage.
Joint treatment is a crucial step in preventing grout leakage. For horizontal joints, sponge strips or double-sided adhesive strips can be pasted inside the formwork. The formwork's own weight will ensure a tight seal. The adhesive strip width should be slightly larger than the joint width to avoid exposure and contamination of the concrete. Vertical joints use a "mother-and-child" type, with staggered joints of the formwork creating a natural seal. Wooden blocks are used to compact the outer side for added integrity. For external corners, a "double-child" formwork installation method is used. For internal corners, special wooden blocks are added, employing a board-over-beam and board-over-wall installation method to ensure tight, square joints at both corners and prevent grout seepage.
Root sealing is a high-risk area for grout leakage and requires multiple measures. The base layer at the base of exterior wall columns needs to be chiseled down to a solid concrete surface, removing laitance and debris, and moistened with water without standing water. For regular areas, a "rubber pad + angle steel" sealing method can be used. A rubber pad of uniform thickness is laid between the bottom of the formwork and the base layer, compacted with angle steel on the outside, and fixed using the formwork back brace. For continuous sections such as exterior walls and stairwells, a "pre-installed tie rods + sponge strips" approach can be used. Sponge strips are pasted at the bottom of the joint where the upper formwork extends downwards, and the pre-installed tie rods are used to reinforce the base. For walls in lowered slab areas such as kitchens and bathrooms, the formwork must extend to the bottom of the lowered slab, and steel pipes are used for top reinforcement to ensure bottom stability.
The stability of the template panel system directly affects the formwork's lateral pressure resistance. During the design phase, the specifications and spacing of the tie bolts, as well as the material and spacing of the secondary and primary ribs, must be calculated based on the lateral pressure of the concrete. The distance from the first tie bolt to the base should not exceed 200mm, and the spacing of the lower bolts should be smaller than the upper spacing, forming a "larger at the top, smaller at the bottom" distribution pattern to enhance base restraint. The bottom of the support uprights must be firmly padded, and the ground bracing must be installed according to specifications to prevent formwork displacement due to settlement of the support system during pouring. Tie bolts should be tightened with double nuts to prevent loosening that could lead to formwork bulging and grout leakage.
The concrete mix proportion and pouring process must be compatible with the template panel system. The concrete slump needs to be adjusted according to the pumping height and temperature. Excessive slump can lead to excessive grout flow and leakage, while insufficient slump makes compaction difficult. During pouring, concrete should be poured and vibrated in layers to avoid segregation caused by aggregate concentration. When the free fall height exceeds 2m, a chute or drop pipe should be used to reduce the impact of concrete on the formwork. The vibrator should not be too close to the formwork, and the vibration time should be moderate to prevent loosening of joints due to excessive vibration.
Construction management is crucial for preventing grout leakage. Thorough technical briefings are essential to ensure that construction personnel master the key operational points of formwork installation, joint treatment, and support erection. Strict quality inspection is necessary. After formwork installation, the tightness of joints, the stability of supports, and the verticality of the formwork must be checked, and problems should be rectified promptly. During concrete pouring, dedicated personnel should inspect the formwork. If leakage is found, pouring should be immediately stopped and addressed to prevent the defect from escalating.
Reducing grout leakage in the template panel system requires optimization of the entire process, including materials, design, technology, and management. By selecting high-precision templates, meticulous joint treatment, multiple root sealing methods, stable support systems, reasonable concrete mix proportions, standardized vibration processes, and strict construction management, the risk of grout leakage can be significantly reduced, and the quality of concrete pouring and construction efficiency can be improved.
