Exploring the potential of low cement concrete through a student concrete competition

A common method used to increase the strength of concrete is to add more cement to reduce the water-to-cement ratio. However, this is not always acceptable as adding more cement increases autogenous shrinkage, thermal and shrinkage cracking, and the cost of concrete production. By appropriately using superplasticizers, high-performance low cement concrete (LCC) can be produced. This study explores the potential of LCC by limiting cement content, adding alternative cementitious materials, and superplasticizers. Data was collected from the outcome of an annual National Student Concrete Competition conducted in Indonesia over three consecutive years. The new concept of LCC mix design was explained to all participants, i.e., civil engineering students, before they made their concrete specimens. Following the competition, all mixture compositions and their resulting concrete properties were analyzed. It was found that the participants’ knowledge on the use of superplasticizer and cementitious materials was the most notable challenge. Nevertheless, they discovered that making LCC is a possibility. Concrete with a compressive strength of 50 MPa (7252 psi) can be made using cement content as low as 200 kg/m3 (337 lb/yd3) with sufficient workability. Furthermore, the effect of several factors on the performance LCC is described in this study.