You might not want to hear this but concrete is supposed to crack. As concrete hardens it begins to shrink ever so slightly. In fact, concrete shrinks 1/16th of an inch for every ten feet of length that is placed. Which may result in cracks that are 1/8th inches thick
Wise concrete finishers know this and install contraction or crack control joints that encourage the concrete to crack at these locations. For the joints to work correctly they need to be a minimum depth. Always make sure that these joints are cut 1/4 or more of the thickness of the slab.
There are multiple factors contribute to the cracks. To name a few: Settling, changes in temperatures, weight pressure fluctuations, changes in humidity, shrinkage and expansion, etc. In addition, while 85% of the curing process occurs within the first 3-4 weeks, full curing process takes more than 6 months, etc. If cracks are 1/5″ or wider, it is a sign of poor concrete mix or reinforcement inside of the concrete. Normally smaller cracks are to be sealed after a year of use. Alternatively, it may be painted or epoxy polyurethane covering may be applied. And in no way, they are affecting the sturdiness of your garage foundation. At Alta Home, we offer placement of control joints at no extra cost upon customer request. This will ensure all those smaller cracks follow the saw cut in the middle of the pad.