The Effect of Fiber on the Green Strength and Buildability of High-Strength 3D Printing Concrete

Abstract

This paper presents four parameters in 3D Printing Concrete (3DPC) in the fresh state. Flowability, extrudability, open time, and buildability. In addition, this paper also introduces a new method to obtain the green strength of fresh concrete. The high-strength concrete mixture was used as a base mix design. The water to binder ratio and admixture were tuned to obtain the 3DPC that satisfied those four parameters. The 3DPC mix design used cement, silica fume, and reactive powder as a binder with a ratio of 3:1:1. The ratio of sand and binder was 0.9. The water to binder ratio (w/b) was 0.14 with the addition of a superplasticizer and accelerator. To increase the buildability, polyvinyl alcohol (PVA) fiber was added by 0.2% of concrete volume. It had a 30 mm slump, 110 mm flow, 1.1 SRF, 85 minutes of open time, and 7 KPa green strength in 75 minutes. This mix design was able to be printed into 40 layers of 100×400 mm cylinder.