EFEK PENAMBAHAN SERAT POLYPROPYLENE TERHADAP KARAKTERISTIK BETON SEGAR JENIS SELF-COMPACTING CONCRETE

Abstract

The Self-Compacting Concrete (SCC) can be defined as a type of concrete that able to flow and consolidate under its own weight, completely fill the formwork even in the presence of dense reinforcement, maintaining its homogeneity and without the need for any additional compaction. Similar with other types of cement-based materials, SCC also has a brittle characteristic. This problem can be encountered by adding fibers in to the concrete mix. Unlike its effects to hardened concrete, the presence of fibers in concrete mixes can cause significant deterioration to the concrete workability. This research was conducted to investigate effects of polypropylene fiber addition on four key characteristics of SCC in the fresh state. In this research, concrete mixes were prepared containing 0, 0.05, 0.10, and 0.15 percent volume fraction of polypropylene fibers. Fresh properties were evaluated based on its passing ability, flowability, viscosity, and segregation resistance using J-ring, Slump flow, and Sieve Segregation Resistance tests. Test results indicate polypropylene fibers reduce flowability and passing ability but will increase viscosity and segregation ratio of SCC. Furthermore, it can be concluded that polypropylene fiber reduce deformability of SCC in the fresh state. It can be suggested that polypropylene fibers allowed to be added into SCC mixes up to 0.10 percent by volume of concrete.

Keywords   : Self-Compacting Concrete, Polypropylene fiber, Fresh characteristics

ABSTRAK

Self-Compacting Concrete (SCC) adalah jenis beton dengan daya alir yang sangat baik dan mampu memadat secara mandiri. Penambahan serat dalam beton segar dapat menyebabkan perubahan karakteristik beton segar. Dengan demikian, perlu dilakukan penelitian untuk memperoleh campuran adukan beton segar yang memenuhi persyaratan deformability dan ketahanan segregasi SCC. Penambahan serat polypropylene diberikan sebesar 0%, 0,05%, 0,1%, dan 0,15%, berdasarkan volume beton. Evaluasi dilakukan terhadap empat karakteristik utama beton segar SCC, yaitu: flowability (slump-flow), viscosity (T₅₀₀), passing ability (J-Ring Test), dan ketahanan segregasi (GTM screen stability test). Penambahan serat polypropylene menyebabkan berkurangnya flowability SCC. Kondisi SCC masih dapat dicapai saat serat polypropylene ditambahkan sebesar 0,10% dari volume beton dengan slump-flow 556 mm. Pada penambahan 0,15% beton segar tidak dapat memenuhi syarat flowability SCC dengan slump-flow 428 mm. Penambahan serat polypropylene menambah viskositas SCC. Kondisi SCC masih dapat dicapai saat serat polypropylene ditambahkan sampai dengan 0,10% dari volume beton dengan T₅₀₀ 1,40 detik. Pada penambahan 0,15% beton segar melampaui batas maksimal viskositas SCC, dimana nilai T₅₀₀ sudah tidak terukur. Penambahan serat polypropylene menurunkan passing ability SCC. Kondisi SCC masih dapat dicapai saat serat polypropylene ditambahkan sampai dengan 0,10% dari volume beton dengan beda elevasi 7,9 mm. Pada penambahan 0,15%, beton segar tidak dapat memenuhi syarat minimal passing ability SCC dimana beda elevasi mencapai 10,6 mm. Penambahan serat polypropylene mengurangi rasio segregasi SCC. Semua varian dalam penelitian ini dapat memenuhi syarat rasio segregasi beton segar SCC.

Kata Kunci       : Self Compacting Concrete, Serat Polypropylene, Karakteristik Beton Segar