# Early-Age Cracking in Concrete: Causes, Consequences, Remedial Measures, and Recommendations
## 4 Factors Affecting Early-Age Cracking
### Materials and Mix Parameters
A smaller hydration heat diffusion length increases the possibility of early-age cracking. Materials selection and mix proportions or parameters, including water-to-cement ratio and the use of silica fume influence the shrinkage behavior of concrete by affecting the fineness of the pore structure in concrete. In the case of finer pores, a large compressive stress acts on the pore walls, consequently causing a greater autogenous shrinkage at both early and later ages [12]. Also, the size of aggregate influences the mechanical properties of hardened concrete; such as Young's modulus of elasticity and fracture energy that are related to the cracking behavior. A larger coarse aggregate size decreases the tensile strength and Young's modulus of hardened concrete, because larger aggregates increase the size of the transition zone, which is the weak interface between aggregate and cement paste [53]. Moreover, an increase in the coarse aggregate size decreases the cohesiveness, thus increasing the slump of concrete [53]. A high slump of concrete not only increases the possibility of cracking but may decrease the bond strength between concrete and reinforcement [14] due to more free water. The aggregates tend to reduce the autogenous shrinkage and creep due to diluting effects [54]. However, their contribution in reducing autogenous shrinkage is limited [53]. Reinforcement is able to reduce free deformation, but the effect is limited since the thermal coefficients of reinforcement and concrete are similar [12; 53; 55]. On the other hand, steel reinforcement is believed to cause undesirable surface cracks due to its restraining effects as mentioned in Section 4.1. However, the steel reinforcement has the ability to increase the tensile strain capacity of concrete and the minor cracks led by reinforcement can be delayed until the moment at which major cracks are formed [55]. The bar size also influences the cracking in concrete, where a larger bar size increases the tendency of cracking [40; 41]. [PERSON] et al. [56] studied the shrinkage-induced early-age cracking risk of concrete due to the degree of water saturation of aggregates. They studied three different degrees of saturation (0%, 50%, and 100%). They reported that the concrete with fully saturated aggregates is susceptible for the highest potential of cracking risk. This is because of the rapid evolution of modulus of elasticity from initial setting time. The concrete with partially saturated aggregates showed the highest early-age plastic and autogenous shrinkages. They also reported that the amount of added water during concrete mixing greatly affects the early-age cracking behavior of concrete. The exposure conditions, pore moisture suction, and the depth of crack are the major causes of crack propagation in concrete at the early-age [57]. Proper compaction and effective curing can minimize the severity of cracking in concrete at the early-age. The increased amount of cementitious materials increases the risk of the early-age cracking in concrete. Therefore, high-performance concrete suffers high levels of autogenous shrinkage, tensile creep, and cracking during the early age due to the high volume of cementitious materials [11].