ACI Global Home Middle East Region Portal Western Europe Region Portal
Email Address is required Invalid Email Address
In today’s market, it is imperative to be knowledgeable and have an edge over the competition. ACI members have it…they are engaged, informed, and stay up to date by taking advantage of benefits that ACI membership provides them.
Read more about membership
Learn More
Become an ACI Member
Topics In Concrete
Home > Frequently Asked Questions
In This Section
Frequently Asked Questions
Submit a Question
Search other resources on the ACI website for answers to technical questions
Q. What is unsoundness in portland cement, and how is it detected and avoided? A. Concrete that shows excessive expansion after setting is said to contain unsound cement. In former times, this was a serious problem for concrete. In more recent times, better manufacturing, testing, and controls have almost completely eliminated unsound cement. Unsoundness is caused by free lime and magnesia in the clinker in sufficient quantity so that, upon hydration, excessive expansion and damage to concrete can occur. The presence of such is detected by the autoclave expansion test ASTM C 151. Unsoundness can be avoided by minimizing these expansive constituents. References: SP-1(02); ACI 225R-19; E3-13; ASTM C150; ASTM C151; ASTM C595; ASTM C1157 Topics in Concrete: Cementitious Material; Concrete Fundamentals
Q. What is unsoundness in portland cement, and how is it detected and avoided?
A. Concrete that shows excessive expansion after setting is said to contain unsound cement. In former times, this was a serious problem for concrete. In more recent times, better manufacturing, testing, and controls have almost completely eliminated unsound cement. Unsoundness is caused by free lime and magnesia in the clinker in sufficient quantity so that, upon hydration, excessive expansion and damage to concrete can occur. The presence of such is detected by the autoclave expansion test ASTM C 151. Unsoundness can be avoided by minimizing these expansive constituents.
References: SP-1(02); ACI 225R-19; E3-13; ASTM C150; ASTM C151; ASTM C595; ASTM C1157
Topics in Concrete: Cementitious Material; Concrete Fundamentals