diff --git a/src/paveit/datamodels/material.py b/src/paveit/datamodels/material.py
index 8876d43..11fff45 100755
--- a/src/paveit/datamodels/material.py
+++ b/src/paveit/datamodels/material.py
@@ -108,7 +108,7 @@ class Kompaktasphalt(Material):
 
 class Aggregate(Material):
     
-    norm = StringField(required=True, default='TL Gestein-StB')
+    norm = EnumField(NormEnum, default=NormEnum.TLGestein2018)
     name = StringField(required=True)
     
     delivery_grain = LazyReferenceField(DeliveryGrain,