Context!!!
In the context Paul metaphorically refers to the church at Corinth as "God's building", verse 9
In verse 10 Paul calls himself a "masterbuilder" who laid a "foundation" at Corinth.
Paul is making a metaphorical comparison between build a building and build a church. When one builds a building, he lays a foundation and builds upon that foundation and the building is only as strong as the material used, verse 12.
Likewise building the church is like building a building for in building the church at Corinth Paul "laid the foundation" of the "building". That is, in building the church at Corinth Paul 'laid the foundation" by making the initial converts. Others came behind Paul and built upon that foundation laid by Paul by asking even more converts. And the church is only as strong as the faith of those converts made.
1 Cor 9:1 Am I not an apostle? am I not free? have I not seen Jesus Christ our Lord? are not ye my work in the Lord?
Paul calls these Corinthians his "work".
Verse 13 Every man's work (convert) shall be made manifest: for the day shall declare it, because it shall be revealed by fire; and the fire shall try every man's work (convert) of what sort it is.
Verse 14 If any man's work (convert) abide which he hath built thereupon, he shall receive a reward.
On judgment day, those Corinthian converts that are judged to be saved, Paul will receive a reward for them.
Verse 15 If any man's work shall be burned, he shall suffer loss: but he himself shall be saved; yet so as by fire.
Converts of Paul that are judged to be burned/lost then Paul will suffer some loss over that lost convert but Paul himself will be saved if he remains faith - is not a castaway, 1 Cor 9:27. Paul's converts in Galatia had left the gospel, quit obeying the truth, fallen from grace and Paul said of them "I am afraid of you, lest I have bestowed upon you labour/WORK in vain." If those Galatians did not repent and end up burned/lost, then Paul will suffer a sense of loss over them, his work in making those converts would be in vain.