Where did these cracks come from?

Early-age drying shrinkage was measured on concrete slabs in a Finnish test arrangement. The tests evaluated the factors influencing the concrete’s shrinkage magnitude and likelihood of cracking. In many cases, the shrinkage occurring immediately after placing (< 24 h) was greater than standard long-term shrinkage due to environmental conditions. Construction practice needs to note these early-age risks and take precautions to prevent detrimental shrinkage. Some environmental conditions, such as wind, were examined as well as prevention methods, such as curing with water or chemical compounds. The early-age shrinkage magnitude was directly correlated to the amount of evaporation from the concrete.