Technical Questions

ACI Committees, Membership, and Staff have answered common questions on a variety of concrete related topics.

The effect of aggregate shape on concrete strength

Q. How does the shape of the particles affect the strength in concretes of the same cementitious material content?


A. Particle shape principally affects the w/cm by its effect on water demand and amount of paste required for workability of a given mixture. Also, the bond with the cement paste may be weakened due to the accumulation of bleed water under the relatively large surface areas of flat particles of aggregate. At the same w/cm, concrete with angular crushed stone aggregate ordinarily has a higher flexural strength than concrete with rounded gravel aggregate.


References: SP-1(02); E-1(16); ACI 221R-96; ACI 213R-14; ACI PRC-211.1-22; ACI 211.4R-08; ASTM C33

Topics in Concrete: Aggregate; Concrete Fundamentals; Materials; Mixture Proportioning

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