Cracking of concrete

S. P. Shah, M.E. Karaguler and M. Sarigaphuti Effects of Shrinkage-Reducing Admixtures on Restrained Shrinkage Cracking of Concrete. ACI Materials Journal, No.89-M33, May-June, (1992), p. 289-295. 

Medium damage, cracks (0.5-5 mm) and tilt (10-100) of brick walls, cracks of concrete walls, building top shaking out, most part damage... 

Severe damage, windows and doors destroyed, cracks (>50 mm) and high tilt of brick walls, partial falling down, severe cracks of concrete walls, falling down of brick buildings... 

Qin Weizu. Shrinkage and cracking of concrete and its evaluation and prevention. Concrete 2001 ... 

Thus by eliminating at least one of these factors the expansion and cracking of concrete may be prevented. 

Yokomichi H, Ikeda I and Matsuoka K (1964) Elastic wave propagation due to cracking of concrete. Cement Concrete Japan 212 2-6... 

Bituminous cement n. A black substance available in solid, semisohd, or hquid states at normal temperatures composed of mixed indeterminate hydrocarbons appreciably soluble only in carbon disulfide or other volatile hquid hydrocarbon especially used in seahng built-up roofing and between joints and in cracks of concrete pavements. 

Service air Air compressor foundation Foundation failure Special surveillance Cracking of concrete Vibration —... 

Figure 9.2 Cracking of concrete specimens with different ratio of strength of matrix to that of aggregate grains ...

Figure 7.24 Cracking of concrete cover in marine environment.

Concrete may deteriorate if adequate precautions are not exercised to protect it from adverse effects that could result from exposure to natural or artificial conditions. Several physical, chemical, and electrochemical processes are known to induce cracking of concrete. Concrete can have durability problems as a consequence of its exposure to seawater, sulfates, chlorides, freeze-thaw action, carbon dioxide, etc., or when it is attacked by artificially induced processes such as exposure to acids and salts in chemical plants or to fire. In recent years, a new type of durability problem was encountered that involved use of steam cured concrete products. The distress was caused by the formation of delayed ettringite. If the raw materials in concrete are not carefully controlled, there may be an eventual failure of concrete elements, eg., the presence of excess alkali in concrete that promotes alkali-aggregate expansion reaction, harmful impurities in the aggregates, or the presence of excess amounts of dead-burnt MgO. Thermal techniques in combination with others have been employed with success to examine the raw materials as well as the failed concrete. The knowledge gained from such work has been applied to produce more durable concrete. 

During the construction of a concrete hydraulic aqueduct in Hunan Province, because of the low depth and long span of the aqueduct,the tensile stresses of the structure were great which may cause the damage because of crack of concrete. SFRC then was adopted to reinforce the aqueduct as shown in Fig.13. Test on such aqueduct showed that the crack and deformation were controlled. 

It is well established that the addition of silica fume to concrete increases the tendency for plastic shrinkage cracking. However, Bayasi and McIntyre [54] showed that this could be compensated for by the addition of fibrillated polypropylene fibres the use of 0.3% by volume of fibres could successfully combat the plastic shrinkage cracking of concrete containing 10% silica fume. 

Structural cracking of concrete core and high wire stress... 

---