Long-term concrete cracking is unavoidable, and large openings impact concrete durability [4,5]. In hot and dry areas of the world, high air temperature, wind, and low relative humidity are also known to impact durability [6], as they can cause high plastic and drying shrinkage strains in concrete [7,8,9]. ACI 224R-01 [10] attributes early-age concrete cracks to excessive evaporation due to environmental conditions prior to concrete setting. The earlier concrete cracks develop, the shorter the serviceable life of concrete is expected [11,12]. Plastic shrinkage cracks are the earliest to appear, as they occur two-three hours after casting, prior to setting. Subsequent propagation of plastic shrinkage cracks will allow ingress of water and offensive agents such as chlorides and increase the possibility of concrete deterioration and corrosion of steel rebars [13,14]. Plastic shrinkage cracks not only reduce concrete durability but are also aesthetically undesirable [15].
Again, the use of RTSF at a dosage of 30 kg/m3 prevented cracking in the specimens subjected to the Low and Medium wind speeds only, whilst 40 kg/m3 of RTSF was effective in preventing cracking at High wind speeds.
Civil 3D 2016 Crack File Only 32 Bit
At low wind speeds (3 m/s), the evaporation rate reduces but the plain concrete cracks only a bit later and a bit less wide. Hence, at the ranges used, wind speed seems to play a less important role than temperature.
Al-Tulaian et al. [83] used recycled plastic fibers (RP) with two lengths (50 and 20 mm) to restrain plastic shrinkage in mortar concrete at high temperatures (45 C) and found that RP reduced the plastic shrinkage cracks by up to 70% for a volume fraction of 1.5% and fiber length of 50 mm. Hence, steel fibers appear to be the only solution to stop cracks completely at these high temperatures. 2ff7e9595c
Comments