10 year old house, cement patio with stress releif grooves about every 8 feet. Patio had no problems until last year. stress grooves have cracked and have slightly separated (same elevation, just separated about 1/4 inch). I live in Utah and have a wide temperature range (0-100 deg F). Should I be filling in the cracked grooves with something? If so what?. I thought about filling with expanding foam to keep water out but I don't want to do something dumb. Any suggestions would be great.