so me and a couple friends are at one of are friends houses and we had water bottles and my friend spilt the water on the concrete but the concrete stayed the same color as all the other concrete. it didnt get darker or anything like it got wet so were all like wtf?!?! so we dumped the whole water bottle out and there is a big area that dosnt get wet ( like the water is on top of the concrete but theres like a layer or something stoping the concrete from getting wet ) and then in the same pool of water it parts of it become wet when water hits it ( i know that cuz the concrete gets the darker color wen it gets wet ). does anyone have any freaking idea what did this cuz he wont tell us. also he uses the gas powerd rc cars and stuff so he always has a bunch of crap laying around and his dad is a machanic. cant spell
we asked him if there it was oil he said no it wasnt. theres something else that does that.