Studi Eksperimental Penambahan Superplasticizer Pada Beton Bertulang Terkait Kerangan Korosi Baja Tulang Dengan Metode Alami Dan Paksa

Beton bertulang merupakan modifikasi beton dalam bangunan untuk meningkatkan kekuatan tarik pada beton. Jika baja tulang terkorosi, kekuatan dari beton dapat turun hingga lebih rendah dibandingkan kekuatan beton tanpa tulangan. Korosi ini dapat disebabkan masuknya media korosif menuju baja tulang. Upaya perlambatan masuknya media korosif diperlukan modifikasi terhadap beton. Salah satu modifikasi beton adalah penggunaan admixture (superplasticizer) untuk meningkatkan kekuatan tekan dan mengurangi tingkat porositas. Pada penelitian ini dipelajari pengaruh pemberian 0,8 % superplasticizer viscocrete-10 dalam media korosi yang dipercepat. Spesimen yang digunakan adalah beton yang mempunyai rasio air- semen (w/c ratio) 0,5 untuk spesimen tanpa penambahan superplasticizer dan 0,4 untuk spesimen dengan penambahan superplasticizer. Beton berbentuk silinder pejal berukuran panjang 120 mm dan diameter 50,8 mm. Baja polos berdiameter 11 mm dan panjang 118 mm dipilih sebagai tulangan beton. Pengujian kuat tekan dan pengujian porositas dilakukan untuk mengetahui karakteristik beton. Selanjutnya dilakukan pengkondisian ialah perendaman spesimen beton bertulang di larutan NaCl 12,5 % dengan tinggi perendaman beton sebesar 45 mm dan lama waktu perendaman 60 hari dengan metode alami dan paksa. Pada metode paksa, digunakan elektroda stainless steel yang bertindak sebagai katoda yang dihubungkan dengan arus 5 mA. Secara periodik, setelah 15 hari pengkondisian dilakukan pengamatan yang meliputi perubahan fisik beton bertulang, perubahan kandungan ion klorida di selimut beton pada ketinggian dan kedalaman tertentu, visualisasi penampang vertikal baja tulang, tinggi korosi yang terlihat pada baja tulang, dan ketebalan pengurangan baja tulang akibat serangan korosi. Hasil penelitian ini menunjukkan bahwa serangan korosi ke arah radial pada beton superplasticizer lebih banyak dibandingkan beton tanpa superplasticizer karena superplasticizer telah mengandung ion klorida.Serangan korosi pada daerah perendaman lebih banyak karena daerah tersebut berhadapan langsung dengan katoda (stainless steel), dimana ada pengaruh jarak antara stainless steel dengan baja tulang. Proses kapiler pada interface baja tulang dengan beton tidak berpengaruh jika dilihat dari ketinggian air pada kulit beton yang hampir sama dengan ketinggian korosi pada baja. ================================================================================================================concrete is modified concrete in building to improve the tensile strength of the concrete. If the reinforced steel is corroded, the strength of the concrete can decrease lower than the strength of unreinforced concrete. This corrosion can be caused by the entry of corrosive media to the reinforced steel. In order to prevent the entry of corrosive media, modifications of concrete is required. One of modification is concrete admixture (superplasticizer) to increase the compressive strength and reduce porosity. In this research, it is observed the effect of 0.8% superplasticizer viscocrete-10 accelerated corrosion in the media. The specimens are concretes that have water-cement ratio (w / c ratio) of 0.5 for specimens without the addition of superplasticizer and 0.4 for specimens with the addition of superplasticizer. The shape of concrete is solid cylindrical which is 120 mm in length and 50.8 mm in diameter. Plain steels with diameter 11 mm and length of 118 mm are chosen as the reinforced steel. Testing of compressive strength and porosity are done to determine the characteristics of the concrete. Furthermore, the conditioning is done by soaking reinforced concrete specimens in 12.5% NaCl solution with immersion concrete 45 mm for 60 days with natural and forced methods. In the forced method, stainless steel electrode is used as cathode, connected to the current 5 mA. Periodically, after 15 days of conditioning, the observation is done in physical changes of reinforced concrete, contents of ion chloride changes on concrete cover at certain heights and depths, visualization of vertical cross-section reinforced steel, height of corrosion which is observed in reinforced steel, and thickness of reinforced steel reduction related corrosion attack. The results of this experiment indicate that the corrosion attack on the radial direction of the superplasticizer concrete is greater than without superplasticizer because the composition of superplasticizer have already contained ion chloride. Corrosion attacks on the immersion area greatly because that area faces the cathode directly, related with the influence of the distance between reinforced steel and stainless steel. The process of capillaries in interface donot give the effect because the height of water in the concrete’s skin is same with the height corrosion in steel

MODIFIKASI FOTOBIOREAKTOR HEMAT ENERGI DENGAN LIGHT EMITTING DIODE (LED) UNTUK MENINGKATKAN POPULASI Chlorella spp. DALAM UPAYA PEMENUHAN PAKAN ALAMI LARVA IKAN BANDENG

Fotobioreaktor experiments with fluorescent light sources have been reported can increase the efficiency of photosynthesis in fitoplankton. The results of such experiments show that the density of the fitoplankton culture in fotobioreaktor in line with increasing the intensity of light . Chlorella vulgaris grown in fotobioreaktor with sea water and walne medium. The trial was done with treatment intensity variations  of  different  light  sources, namely  light  source  LED  1  X  3  watt  LED  2  X  3  Watts.  Fotobioreaktor placed in a box by a distance of 10 cm from a source of light. Fotobioreaktor used as a comparison with Neon light source 1 X 8 Watts and Neon 2 X 8 watts. Two-factor ANOVA analysis showed that (p&gt; 0,05), it means there are no interaction effect a between the sides and the source of light . Fotobioreaktor led light source with 1 x 3 watts capable of producing Chlorella vulgaris density equal  to  fotobioreaktor  source  of  a  fluorescent  with  2  x  8  watts.  The  result  indicates  fotobioreaktor light source  with  power  3  watt more  efficient  in  the  use  of electrical  energy  to produce  a  density  of Chlorella  vulgaris.   This  provides  an  indication  that  fotobioreaktor  with  energy-efficient  LED  light source and are able to increase the density of Chlorella Vulgaris.Keyword: Chlorella Vulgaris, Led Emitting Diode, Economical Energ</p