Pengaruh Accelerator Terhadap Kuat Tekan Awal Beton High Volume Fly Ash (HVFA)

Saputra, Fandi Aril (2026) Pengaruh Accelerator Terhadap Kuat Tekan Awal Beton High Volume Fly Ash (HVFA). Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Beton High Volume Fly Ash (HVFA) merupakan alternatif beton berkelanjutan yang menggunakan fly ash dalam kadar tinggi sebagai substitusi semen untuk menekan konsumsi semen sekaligus emisi karbon. Kendala utamanya adalah hidrasi awal yang lambat, sehingga kuat tekan dini rendah dan penerapannya pada elemen struktural menjadi terbatas. Penelitian ini mengevaluasi pengaruh accelerator terhadap kuat tekan awal, shrinkage, dan biaya material beton HVFA, serta menentukan jenis accelerator paling efektif dalam sistem HVFA.
Penelitian dilakukan secara eksperimental di laboratorium menggunakan beton HVFA berkadar fly ash 50% sebagai campuran dasar dan beton OPC sebagai kontrol. Tiga aktivator berbasis kalsium diuji, yaitu calcium nitrate (Ca(NO₃)₂), calcium formate (Ca(HCOO)₂), dan calcium carbonate (CaCO₃), masing-masing berdosis 3% terhadap berat binder. Calcium nitrate dan calcium formate berperan sebagai accelerator kimia, sedangkan calcium carbonate berfungsi sebagai mineral addition/microfiller yang bekerja sebagai nucleation agent. Pengujian mencakup slump, kuat tekan pada umur 1, 3, 7, dan 28 hari dengan dua metode perawatan (curing air normal dan curing air kapur) serta shrinkage selama 56 hari, dilengkapi analisis biaya material dan estimasi reduksi emisi karbon.
Di antara ketiga aktivator, calcium carbonate memberikan peningkatan kuat tekan awal paling efektif dengan nilai 41,5 MPa pada umur 3 hari, melampaui HVFA 50 (36,8 MPa). Sebaliknya, calcium formate dan calcium nitrate menunjukkan perkembangan kuat tekan awal yang tertunda, dengan nilai hanya 5,8 MPa pada umur 1 hari. Calcium formate juga menurunkan slump hingga 20 mm sehingga tidak layak diterapkan di lapangan pada dosis tersebut. Curing air kapur meningkatkan kuat tekan seluruh variasi, diduga karena ketersediaan ion kalsium tambahan yang mengaktifkan reaksi pozzolan fly ash. Pada umur 28 hari, HVFA Carbonate mencapai 61,8 MPa dan HVFA 50 mencapai 60,6 MPa, keduanya melampaui OPC (54,2 MPa). Seluruh campuran HVFA menghasilkan shrinkage lebih rendah dibandingkan OPC, dengan HVFA Carbonate terendah (0,112% pada umur 56 hari). Dari sisi biaya, HVFA 50 paling ekonomis dengan penghematan 21,9% terhadap OPC, sedangkan HVFA Carbonate tetap lebih hemat 11,3% dengan kinerja kuat tekan awal terbaik dan estimasi reduksi emisi karbon sebesar 43,8%.
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High Volume Fly Ash (HVFA) concrete is a sustainable alternative that incorporates a high proportion of fly ash as a cement substitute to reduce both cement consumption and carbon emissions. Its main drawback is slow early-age hydration, which results in low early compressive strength and limits its application in structural elements. This study evaluates the effect of accelerators on the early compressive strength, shrinkage, and material cost of HVFA concrete, and identifies the most effective accelerator for the HVFA system.
The study was conducted experimentally in the laboratory using HVFA concrete with a 50% fly ash content as the base mixture and Ordinary Portland Cement (OPC) concrete as the control. Three calcium-based activators were tested: calcium nitrate (Ca(NO₃)₂), calcium formate (Ca(HCOO)₂), and calcium carbonate (CaCO₃), each at a dosage of 3% by weight of binder. Calcium nitrate and calcium formate acted as chemical accelerators, whereas calcium carbonate served as a mineral addition/microfiller functioning as a nucleation agent. The testing program comprised slump; compressive strength at 1, 3, 7, and 28 days under two curing methods (normal water curing and lime water curing) and shrinkage over 56 days, complemented by a material cost analysis and an estimation of carbon emission reduction.
Among the three activators, calcium carbonate provided the most effective improvement in early compressive strength, reaching 41.5 MPa at 3 days and exceeding HVFA 50 (36.8 MPa). In contrast, calcium formate and calcium nitrate exhibited delayed early-strength development, attaining only 5.8 MPa at 1 day. Calcium formate also reduced the slump to 20 mm, rendering it unsuitable for field application at this dosage. Lime water curing enhanced the compressive strength of all mixtures, presumably due to the additional calcium ions that activated the pozzolanic reaction of the fly ash. At 28 days, HVFA Carbonate reached 61.8 MPa and HVFA 50 reached 60.6 MPa, both surpassing OPC (54.2 MPa). All HVFA mixtures exhibited lower shrinkage than OPC, with HVFA Carbonate recording the lowest value (0.112% at 56 days). In terms of cost, HVFA 50 was the most economical, offering a 21.9% saving relative to OPC, while HVFA Carbonate remained 11.3% cheaper, delivering the best early compressive strength performance and an estimated carbon emission reduction of 43.8%.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Accelerator, Analisis Biaya, Beton HVFA, Kuat Tekan Awal, Shrinkage, Accelerator, Cost Analysis, Early Compressive Strength, High Volume Fly Ash, Shrinkage
Subjects:	T Technology > TA Engineering (General). Civil engineering (General) > TA418.16 Materials--Testing. T Technology > TA Engineering (General). Civil engineering (General) > TA433 Strength of materials. T Technology > TA Engineering (General). Civil engineering (General) > TA441 Aggregates T Technology > TA Engineering (General). Civil engineering (General) > TA681 Concrete construction
Divisions:	Faculty of Vocational > 22301-Civil Infrastructure Engineering (D4)
Depositing User:	FANDI ARIL SAPUTRA
Date Deposited:	01 Aug 2026 03:03
Last Modified:	01 Aug 2026 03:03
URI:	http://repository.its.ac.id/id/eprint/141970

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