When one falls on the asphalt of the street, whether it is dry or wet, does this render his clothes impure, meaning that he cannot perform the prayers therewith? When one falls on the sidewalk, does this render his clothes impure? What is the Sharee'ah-ruling on the clear fluid that comes out several hours after having sexual intercourse?

All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.

Principally things are pure unless there is evidence that they are impure. Such places, streets and sidewalks, are pure in principle. It was narrated that the Prophet, sallallaahu ‘alayhi wa sallam, said: "The earth has been made a place of prayer and a source of purification for me – wherever any member of my nation wants to pray, he may pray." [Al-Bukhari and Muslim; this is the wording of Al-Bukhari]

Given that, you have to avoid such obsessions and doubts unless you are certain that a certain part of the ground or the street is impure. If the impurity is dry and it does not hang to the garment when it touches it, this does not render it impure, provided that it is not wet. If the impurity or the garment is wet, there is no doubt that the affected part of the garment must be washed.

As for the fluid which comes out several hours after having sexual intercourse, if it is semen, it is pure according to the sound opinion. If it is a pre-ejaculatory fluid, it is impure. 

Allaah Knows best.