Leakage Reason and Treatment Measures of Concrete Construction Joint

Phenomenon Construction joints at the aggregate concrete aggregate, concrete crisp, then crouches obvious leakage along the gap.
Cause Analysis
(1) the location of the construction joints to stay improper, the construction joints of the concrete surface is not chiseled, the residue is not washed clean, old and new concrete combination is not strong.
(2) construction joints do not do mouth or not to install water stop.
(3) improper mix design, aggregate focused on the construction joints.
(4) thin concrete walls, reinforced too close, vibrating difficulties, the concrete is not dense.
(5) does not use compensatory shrinkage of concrete, resulting in crooked parts of contraction cracks.
Control measures
(1) waterproof concrete should be continuous pouring, less indwelling construction joints. The construction joints should not be left in the maximum shear or bending moment or floor and the junction of the side wall.
(2) construction joints should be retained as a convex seam, step stitch, flat seam should be buried metal water stop or paste BW seal. Construction joints must be cleaned.
(3) metal water stop with the joints should be full, no gaps. Wall (column) Vertical reinforcement or stirrups cut through the water cut with the hole, should be completed welding repair. BW Seal 7d expansion rate should not be greater than the final expansion rate of 60%, immersed in water, the maximum expansion rate of 150-300%; application, the need to be concrete plaster surface after leveling the plastering layer, paste directly on the leveling Layer surface, joints with nails fixed.
(4) concrete should be used to compensate for shrinkage of concrete, that is, in concrete according to the amount of cement 10% incorporation UEA or WG-HEA micro expansion agent.
(5) pouring the upper concrete, the construction joints should be poured in a concrete mortar and concrete than the same mortar to enhance the bonding of old and new concrete.
（6）高于2m的墙体，宜用串筒或振动溜管浇注入模。 
（7）施工缝处混凝土要仔细振捣，保证混凝土的密实度。 
（8）对施工缝处出现的渗漏点（缝），应视渗漏情况和水压大小，采用促凝胶浆、氰凝（丙凝）灌浆堵漏。

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