ABSTRAK
Teknologibetonmerupakansalahsatu yang paling popular dalamduniakonstruksi, namunbetonkonvensional yang digunakanpadadaerah yang rapattulangandirasasudahtidakmemadailagi.Seringterjadikeropospadabetonkarenapemadatan yang kurangmaksimaldenganalat vibrator padadaerah yang rapattulangan.Self compacting concretememanfaatkanberatsendirinyauntukdapatmengalirmengisiruangantanpaada proses pemadatansamasekali. Penambahanfly ash yang cenderungberbentukbulatdanhalusakanberperansebagailubrikandanfiller. Fly ash sebagailubrikandapatmegurangigayafriksiantaragregat, sehinggadihasilkanbeton yang workable. Penggunaanfly ash dalam volume tinggijugaakanmenambahsifatdeformasidanviskositasbeton, sehinggaakandihasilkanbeton yang dapatmengalirmengisiruangan. Fly ash sebagaifillerdapatmengisironggaantaragregatsehinggabeton yang dihasilkanakanlebihpadat, akibatnyavolume poripadabetonakanlebihkecil. Penelitianinibertujuanuntukmengetahuikarakteristikporositaspadabeton yang memilikikandunganfly ashdalam volume tinggi.
Metodeyang  dipakaidalampenelitianiniadalahmetodeeksperimen, yaitudenganmembuatkomposisicampuranbetondenganpenggunaanfly ashsebagaipenggantisebagian semen padacampuranHVFA-SCC.Pengujianporositasbetondilakukandengan2(dua)metodepengujianyaitu:ASTM 642-97 dan RILEM Recomendation.Pengujianporositasbetondilakukandenganvariasikadarfly ash 50%, 55%, 60%, 65% dan 70% dari volume total semen danfly ashpadaumur 7 hari, 28 hari,56 hariserta 90 hari.
Hasilpenelitianmenunjukkanbahwapenggunaanfly ashdengankadartertentudapatmempengaruhiporositasdaricampuranbeton. Padapenelitianinisemakinbesarkadarfly ashtidakmenjaminhasilpengujianporositasakansemakinbaik pula, namunpadapengujianinimemilikinilai optimum. Padapengujianmetode RILEM Recommendationkadarfly ash 63,83?ri volume total semen danfly ashmemilikinilaiporositas yang paling optimumdengannilaiporositas 5,27%, sedangkanpadametode ASTM C642-97 kadarfly ash 65,41?ri volume total semen danfly ashmemilikinilaiporositas yang paling optimum dengannilaiporositas 1,69%
Kata kunci :fly ash, porositas, HVFA-SCC.
ABSTRACT
Concrete technology is one of the most popular in the world of construction, but the conventional concrete is used in areas that meeting felt reinforcement is no longer sufficient. It often happens porous concrete for less than the maximum compaction by means of a vibrator in the area of dense reinforcement. Self compacting concrete utilizing its own weight for flowable fill the room without any compaction process at all. The addition of fly ash which tend to be round and smooth will act as a lubricant and a filler. Fly ash as a lubricant can decimate friction between the aggregate, so that the resulting concrete workable. The use of fly ash in high volumes will also increase the deformation properties and viscosity of concrete, that will produce concrete that can flow to fill the room. Fly ash as filler can fill the cavity between the aggregate so that the resulting concrete will be more dense, pore volume of the concrete result will be smaller. This study aims to determine the porosity characteristics in concrete that contains fly ash in high volume.
The method used inthis study is theexperimental method, namely bymakingthe composition ofthe concrete mixturewiththe use offly ashas apartialsubstitute forcementin themixHVFA-SCC. Concreteporositytestingis donewithtwo (2) testing methodsare:ASTM642-97andRILEMRecommendation. Concreteporositytestingis donewithfly ashcontent variationof 50%, 55%, 60%, 65% and70% of thetotalvolumeof cementandfly ashat the age of7days, 28 days, 56 daysand90 days.
The results showed that the use of fly ash with certain levels can affect the porosity of the concrete mix. In this study, the greater the levels of fly ash does not guarantee the porosity test results will be the better, but in this test has the optimum value. On testing methods RILEM Recommendation fly ash content of 63.83% of the total volume of cement and fly ash has a porosity value most optimum porosity value of 5.27%, while the method of ASTM C642-97 fly ash content of 65.41% of the total volume cement and fly ash has a porosity value most optimum porosity value of 1.69%
Keywords: fly ash, porosity, HVFA-SCC.