Cracking concrete

Jankovic, D., Kiintz, M. and Van Mier, J.G.M. (2001) Numerical Analysis of Moisture Flow and Concrete Cracking by means of Lattice Type Models. Proceedings of FraMCoS-4, Cachan, France 1, 231-238. 

Sulphate waters. The influence of these waters, mostly groundwaters, on concrete is the most intensive. The main reason for the destruction of concrete by sulphate waters is the reaction of sulphate anions with tricaJcium aluminate to form the already mentioned strongly hydrated compound. This compound crystallizes in needles with a considerable increase in volume. Due to the considerable crystallization pressure the concrete cracks, becomes porous and the destructive effects of aggressive water penetrate deeper through the cracks formed. 

Rebars not entirely embedded in concrete. Macrocell corrosion can occur when there are macroscopic defects in the concrete (cracks with large width, honeycombs, delaminations, etc.) or when there are metallic parts connected to the rebars that are only partially embedded in the concrete. This case is important for structures immersed in seawater or in aggressive soil. Besides being subjected to direct attack, those parts in direct contact with water or soil may also undergo more severe attack caused by the galvanic coupling with steel embedded in concrete. 

Chloride-induced reinforcement corrosion and concrete cracking simulation was investigated by Chen and Mahadevan [35] using Faraday s law to develop a... 

Table 9.1 Equations published in the past from researchers regarding time to concrete cracking due to corrosion of embedded reinforcementThe equations have been modified from the original papers for uniformity in presentation (Aligizaki,2006). 

Ad = Reduction of steel diameter due to corrosion to cause concrete cracking At = Increase in bar diameter a = Coefficient that depends on type of corrosion = Density of the oxide Pjt = Density of steel. 

Most materials have a finite life. Metals corrode they can also suffer from fatigue. Wood rots, and concrete cracks or suffers from various chemical degradation processes. Natural rubber can perish as a result of ozone attack. All these materials have been around for long enough for us to know and make allowance for their weaknesses. 

When the load on beam LI applied to 21.7 KN, concrete cracks begin to appear at the tension zone of the test beam. And the cracks developed with the increase of load. But the cracks are in control. The steel yield until the load increase to 132.6 KN. But the concrete crack is still relatively thin which is less than 0.1 mm. At this point, the midspan deflection is 14.51 mm. Continue to increase the load after steel yielded, the deformation of the test beam speed, cracks width become obvious. When the load applied to 165.6 KN. The N0.4 crack vertical in the middle of the beam achieved rapid development. Its width reached 0.2 mm and its deflection reached 19.72 mm. When the load applied to 169.8 KN, the crack become clear. The width of N0.4 crack come to 0.5 mm, the width of the cracks beyond the limit. And the cracks in the style of eight extension show on both sidesof the beam. We concluded that the artifacts began to breakdown. When the load applied to 174.8 KN, the concretes in the compressive zone were completely splited. the test beam reached the ultimate load, its deflection come to 31.19 mm. We concluded that the artifacts were completely destroyed. 

In general, concrete cracking may be distinguished into two cracking that developed when the concrete is fresh (plastic stage) and cracking that developed when the concrete is hardened. 

It is better to leave most of the concrete cracking unrepaired than to attempt an inadequate or improper repair (Smoak 2012). 

Resulting from variability of input quantity 25 simulation steps on the base of RSM method under system ANSYS-CRACK was realized (Kralik,J. 2009a). The probability of loss BT- structure integrity was calculated from 10 Monte Carlo simulations for 25 steps of approximation method RSM on the full structural FEM model. The probability analysis was realized for structural FEM model considering the concrete cracking. 

Prestiessed concrete, aggregates 0/32 mm cracked beam open air test facility ETH Zurich Concrete cracking Fuji KSB 250 P-waves - next crack (Koppel and Vogel 2000)... 

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