1 Small residential projects tend to cost more per square foot and may be subject to a minimum charge of $500-$1,000 or more. 2  Resurfacing an average 500-square-foot concrete driveway typically costs $2,000-$5,000. ThisOldHouse.com estimates it took two people five hours and six bags ($150-$180) of material to resurface a 9'x27' driveway and a 3'x18' walkway (about 300 square feet). 2  Renting a pressure washer to clean the existing concrete before resurfacing can add $40-$75 to the total DIY costs.
At what point you declare someone mentally mature is hard to define but given that wisdom from life experience would be a good indicator of maturity then the age of someone would imply more life experience. It depends if they have learnt from it I guess.
Maturity. Concrete maturity indicates how far curing has progressed. Maturity is the relationship between concrete temperature, time, and strength gain. It is represented by an index value that can be measured in real time in the field.