Cracking in concrete occurs by retention of its volume change caused by drying shrinkage, Hydration heat, rapid change of temperature or humidity, etc. Furthermore, structural cracking caused by corrosion of re-bars which originates from carbonation of concrete, salt damage, etc. after construction, earthquakes, land dipping. These cracking spoil neither beauty nor leading to decline of performance, water leakage, and finally partial collapse of the structure.
The proposals on measures to cracking is to compensate cracking caused by drying shrinkage or Hydration heat, etc., and these are applied at building concrete structure.
1. The proposal on compensation of cracking on early-stage
Cracking in concrete or mortar occurs when the force for cracking is beyond the tensile strength of the concrete or the mortar, and the force for cracking occurs by the complex factors such as various kinds of temperatures, dissipation of water, difference of degree of retention, or volume change, etc. on the first stage of the occurrence of the force. According to previously setting up Hyper Net 60 at parts around openings, corners or ceiling where cracking is concerned, possibility of cracking remarkably reduces.
Hyper Net 60
Hyper Net 60
Hyper Net 60
2. The proposal on compensation of cracking caused by drying shrinkage
Drying shrinkage cracking occurs by the combination between the transformations caused by dissipation of water according to the drying and the retention. There are two methods to compensate the drying shrinkage cracking; one is to dose and mix an expansive additive or a shrinkage reducing agent into concrete when it is produced, and the other is to apply a shrinkage reducing agent to the surface of the hardened concrete as soon as the concrete form is removed.
Method of dosing when concrete is produced (Ready mixed concrete)
The following expansive additive or shrinkage reducing agent we propose can compensate the transformation of shrinkage, so that the occurrence of cracking caused by drying shrinkage reduces.
Expansive additive for concrete
Concrete mixed with Hyper Expan, an expansive additive for concrete, appropriately expands on the early stage, and compressive force is introduced into the concrete by retaining materials such as re-bars, which is called Pre-stress Effect. The tensile force generated by drying shrinkage of the concrete etc. is cancelled or deceased by the compressive stress according to the Pre-stress, so that the occurrence of cracking is compensated. Refer to the following figure.
As the family of the expansive additives, the following materials are available.
Hyper Expan : Low Dosage Type
N-EX : High Early Strength Type
Expan : Standard Type
Shrinkage Reducing Agent
Tetraguard, a shrinkage reducing agent, can reduce the drying shrinkage itself according to weakening the tension caused by capillary that is one of main causes of drying shrinkage.
The Effect of Tetraguard
Method of applying a shrinkage reducing agent to the surface of the hardened concrete
By applying Crack Saver, a shrinkage reducing agent, to the surface of concrete of which the form is removed, the Crack Saver penetrates into clink of capillary, reduces the tension of the capillary that is generated by dissipation of water, and finally reduces the drying shrinkage.
Application of Cracksaver
Application Example (Pier of bridge)
Application example (Box Culvert)
3. The proposal on compensation of cracking caused by heat generated by reaction of hydration
Recently, concrete structures are getting bigger or larger and the application like huge amount of concrete is rapidly cast increases, so that force of heat caused by the reaction of hydration in concrete generates cracking or gives concrete some bad influences which cannot be ignored on the design of concrete. Hyper Expan M can control the generation of the heat caused by the reaction of the hydration on the early stage and can gradually compensate the shrinkage generated at the decrease of concrete temperature with its expansion.
4. Autogenous cracking
Autogenous cracking can be compensated by dosing an expansive additive for concrete or a shrinkage reducing agent to concrete with low ratio of cement quantity, in which the autogenous cracking occurs easily.
Expansive additive for concrete : Hyper Expan, N-EX, Expan
Shrinkage reducing agent : Tetraguard, Crack Saver
