Refractory is one type of ceramic material which is thermostable (high temperature resistant) and has the ability to maintain a good physical and chemical condition at high temperature. Manufacture of refractory in this study using used kiln refractory from cement industry and 15% coal fly ash as additional. This research analyzed the effect of green body pressure produced by physical properties of refractory which made from mixture of used refractory and coal fly ash. Used refractory crushed into large aggregate size -40 +80 mesh and small aggregate size -80 mesh, while fly ash -100 mesh. Then, the two of material mixed. Raw material pressed by press hydrauliuc, with a cube-shaped mold in 5 x 5 x 5 cm size. The pressure of green body varied in 8, 9, 10, 12, and 13 tons. The product tested by archimedes methode to getting apparent porosity and bulk density, and guarded hot plate methode standard use ASTM (C 177-04) to getting the cold crushing strengh and thermal conductivity. Higher pressure molding green body product was obtained with higher compressive strength and bulk density, with lower value of the apparent thermal conductivity and porosity. The highest value for the compressive strength and bulk density was 4.48 MPa; 1.119 g / cm³; the lowest value of thermal conductivity and apparent porosity is 11.60 W / m.K; 22.034%. Those values obtained from green pressure body 13 tons.

Abstrak

Refraktori merupakan salah satu jenis bahan keramik yang tahan terhadap panas (temperatur tinggi) dan memiliki kemampuan untuk mempertahankan kondisinya baik secara fisik maupun kimia pada temperatur tinggi tersebut. Pembuatan refraktori pada penelitian ini menggunakan bahan baku refraktori bekas pakai kiln pabrik semen dengan tambahan 15% fly ash batu bara. Penelitian ini menganalisis pengaruh tekanan green body dari campuran refraktori bekas pakai dan fly ash batu bara yang dihasilkan terhadap sifat fisik refraktori tersebut. Bahan baku refraktori bekas pakai dihaluskan dengan distribusi ukuran agregat besar -40+80 mesh dan ukuran agregat kecil -80 mesh, sedangkan fly ash batu bara berukuran -100 mesh. Pemadatan bahan baku dilakukan dengan menggunakan alat press hydraulic, dengan cetakan berbentuk kubus dengan ukuran 5 x 5 x 5 cm. Dilakukan variasi tekanan campuran green body sebesar 8, 9, 10, 11, 12, dan 13 ton. Pengujian produk dilakukan dengan uji porositas (apparent porosity) dan densitas (bulk density) dengan metode archimedes, kuat tekan (cold crushing strenght), dan uji konduktivitas termal bahan dilakukan dengan metode guarded hot plate menggunakan standarASTM (C 177-04). Pengaruh tekanan green body dari campuran fly ash batu bara dan refraktori bekas pakai kiln terhadap sifat fisik refraktori adalah semakin tinggi tekanan pencetakan green body, maka semakin tinggi nilai kuat tekan dan densitasnya, sedangkan nilai konduktivitas termal dan porositas akan semakin rendah. Nilai tertinggi untuk kuat tekan dan densitas adalah 4,48MPa; 1,119 gr/cm³; nilai terendah konduktivitas termal dan porositas adalah 11,60 W/m.K; 22,034 %. Nilai-nilai tersebut didapatkan dari tekanan green body 13 ton.

M. Schutte, “Refractory recycling earning your environmental brownie points,” The Southern African Institute of Mining and Metallurgy Refractories Conference, 2010, pp. 75-86.

M. B. Berger, “The importance and testing of density/porosity/permeability/pore size for refractories,” The Southern African Institute of Mining and Metallurgy Refractories Conference, 2010, pp. 101- 116.

L. Sylvia, ” Types of refractory materials and their applications,” linked in, 26, october, 2015 [online]. Available:https://www.linkedin.com/pulse/ types-refractory-materials-applications-lesylvia [Accessed: 10, Agust, 2017].

S. Rupnarayan, “Fly ash: characteristics, problems and possible utilization,” Advances in Applied Science Research, vol. 8, no. 3, pp. 32-50, 2017.

Harbinson & Walker, “Brick products,” Handbook of Refractory Practice, Moon Township: Harbinson-Walker Refractory Company, pp. 1-2, 2005.

ASTM C177-04,” Standard test method for steady-state heat flux measurements and thermal transmission properties by means of the guarded-hot-plate,” Annu. B. ASTM Stand., 552, pp.1-23, 2015.

E. Brochen, ”Cold crushing strength,” Review and Improvement of Testing Standard for Refractory Product, 1, october, 2013. [Online] Available:https://www.restar.eu/home/testi ng-standards-for-refractories/cold crushing-strength. [Accessed: 10, Agust, 2017].

N. Toniolo, K. Hurle, G. Taveri, dan A. R. Boccaccini, ”Fly-ash-based geopolymers: How the addition of recycled glass or red mud waste influences the structural and mechanical properties,” Journal of Ceramic Science and Technology, vol. 8, no. 3, pp. 411-419, 2017.DOI: 10.4416/JCST2017-00053.

P. K. Sarker, R. Haque, dan K. V.Ramgolam,” Fracture behaviour of heat cured fly ash based geopolymer concrete,” Mater. Des.,vol. 44, pp. 580-586, 2013. DOI : 10.1016/j.matdes.2012.08.005

P. C. Aitcin, “High-performance concrete demystified,” Concrete International, vol. 15, no. 1, pp. 21-26, 1993.