"用胶土填塞" can be translated as "fill (in/with) glue-soil" or more naturally as "seal with glue-soil" or "plug (a gap/hole) with glue-soil," depending on the context.
Here are a few example sentences:
1、 We need to fill the cracks with glue-soil.
我们需要用胶土填塞裂缝。
2、 They used glue-soil to seal the leaks in the dam.
他们用胶土填塞了大坝的渗漏处。
3、 The workers plugged the holes with glue-soil to prevent water from seeping in.
工人们用胶土填塞了洞口，以防止水渗入。