Antoni Antoni
Petra Christian University

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Long-term Mechanical Properties and Microstructure of Concrete Utilizing Self-Cementing Fly Ash as A Sole Binder Material Oswyn Karsten Wattimena; Antoni Antoni; Djwantoro Hardjito
Civil Engineering Dimension Vol. 25 No. 2 (2023): SEPTEMBER 2023
Publisher : Institute of Research and Community Outreach - Petra Christian University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.9744/ced.25.2.106-114

Abstract

Self-cementing fly ash, containing calcium oxide (CaO) of about 20%, has successfully become a sole binder material in concrete through hydration. A very low water-to-fly ash ratio, e.g., below 0.20, is the main key to achieving the high compressive strength of concrete. This study explores the strength evolution, long-term compressive strength, and mechanical properties of concrete that utilize self-cementing fly ash as a sole binder material. Remarkably, the long-term compressive strength continues to develop over a year, reaching nearly 50 MPa at 365 days, a 34% increase from the 28-day strength. While the other mechanical properties are slightly lower than predictions from empirical formulas for Portland cement concrete, promising results are observed. Scanning Electron Microscope (SEM) images highlight surface-restricted hydration products in self-cementing fly ash, rather than full dissolution of fly ash particles.
Experimental Study of Bond Strength of Embedded Steel Reinforcement in Vibration-Based 3D Printed Concrete Mortar Jimmy Chandra; Alvin Halim; Franky Budiman; Pamuda Pudjisuryadi; Antoni Antoni
Civil Engineering Dimension Vol. 26 No. 2 (2024): SEPTEMBER 2024
Publisher : Institute of Research and Community Outreach - Petra Christian University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.9744/ced.26.2.130-137

Abstract

Many new construction techniques have been developed in recent years, one of them is Three-Dimensional Concrete Printing (3DCP). It offers many advantages such as reduced human error, minimum manpower usage, and shorter construction period. This technique, however, still needs to be studied further to ensure good quality of constructions. This experimental study aims to investigate the bond strength of embedded steel reinforcement in vibration-based 3DCP mortar. The parameters varied are reinforcement diameter and direction of printing. It is found that average bond stress decreases as reinforcement diameter increases. Furthermore, 3DCP specimens with bars placed parallel to the printing direction have relatively higher bond stresses as compared to the ones with bars placed perpendicularly. As compared to conventional cast specimens, 3DCP specimens have higher bond stresses which might be due to vibration-based 3DCP mortar. Moreover, building code formulas significantly underestimate the bond stresses of vibration-based 3DCP specimens tested in this study.