[ABSTRAK
Telah dilakukan penelitian pembuatan beton ringan atau lightweightconcrete (LWC) menggunakan batu apug (BA) dan abu sekam padi (ASP).Sampel beton ringan yang dibuat mengandung BA dengan fraksi berbeda, adapunmaterial semen, pasir, dan abu sekam padi volumenya dijaga tetap. Terdapat duaparameter utama yang menentukan sifat mekanik sampel LWC masing-masingadalah densitas sampel dan rasio air/semen (w/c). Sifat mekanik yang palingutama dari LWC adalah kekuatan tekan. Pada campuran dengan fraksi volumebatu apung terbesar (100%) menghasilkan densitas dan kekuatan tekan palingrendah masing-masing sebesar (1389,6 kg/m3 dan 11,1 MPa). Diketahui bahwamakin rendah fraksi batu apung dalam sampel beton makin tinggi nilai densitasdan kekuatan tekannya, disebabkan oleh tingginya nilai fraksi pori baik poriterbuka maupun pori tertutup dalam sampel beton. Observasi terhadap fotomikroSEM batu apung menunjukkan bahwa terdapat sejumlah besar pori dengan bentukmemanjang ke bagian dalam dari permukaan sampel beton. Pori hadir dengankerapatan jumlah pori relatif besar serta dengan ukuran yang bervariasi. Fakta inimenjelaskan mengapa batu apung besifat ringan karena memiliki densitas massayang rendah. Pola difraksi sinar X sampel beton ringan memperlihatkan dominasifasa kristalin diidentifikasi sebagai fasa quartz (SiO2). Namun dapat dipastikansampel beton ringan terdiri dari fasa campuran antara fasa kristalin dan dengansedikit fasa amorph.Fotomikro SEM beton ringan menunjukkan bahwa senyawa Kalsium SilikatHidrat (CSH) mulai tumbuh pada waktu awal proses hidrasi dan terusberkembang sampai umur beton mencapai umur hidrasi 28 hari yang ditandaidengan sifat fisik yang padat dan peningkatan kekuatan beton. Dapat dipastikanbahwa senyawa CSH ini memiliki peranan penting terhadap pengaturan sifatmekanik seperti kekuatan tekan. Penelitian ini menyimpulkan bahwa batu apungdan abu sekam padi adalah material berbasis silika amorph yang memiliki densitaslebih rendah terutama dibandingkan dengan material pembentuk beton lainnya.Baik densitas dan kekuatan tekan sampel beton ringan ditentukan oleh rasio antarabatu apung dan abu sekam padi. Ditemukan rasio terkecil BA/ASP yaitu 8menghasilkan nilai densitas dan kekuatan tekan optimal, masing-masing pada usiabeton 28 hari sebesar 1891 kg/m3 dan 23 MPa. Komposisi beton ringan yangterbaik diperoleh dari hasil penelitian ini adalah komposisi campuran PCC (1,00) :Pasir (1,00) : ASP (0,05) : BA (0,50) dengan nilai Slump 8 cm ditandai oleh nilairasio antara kuat tekan dan densitas tertinggi adalah 1285.;
ABSTRACT
Research studies on the manufacture of lightweight concrete (LWC) usingpumice and rice husk ash (RHA) materials have been done. LWC samples weremade of pumice materials with a different mass fraction, while the cement, sand,and rice husk ash materials were keep fixed. It was found that there are two mainparameters that determine the mechanical properties of LWC which are densityand the water and cement ratio (w/c ratio). The main mechanical properties ofLWC sample is the power press. Samples with the largest volume fraction ofpumice (100%) resulted in lightest density (1389.6 kg/m3) and the smalleststrength of LWC (11.1 MPa). It was found that, the lower the mass fraction ofpumice in LWC samples, the higher the density values and compressive strengthwere obtained. This was caused by the high mas fraction value of pores, whichwere both open and closed pores. Scanning electron micorscopy (SEM) imagesfor the pumice showed that the there are a large number of regular and structuredpores extending deep inside the surface of the sample. It was observed that porespresent with pore size does not vary significantly but with the density of therelatively large number of pores, indicating pumice has a low mass density. TheXRD pattern of the lightweight concrete samples indicated that the samples weredominated by crystalline phases in which the quartz (SiO2) is the main phase anda small fraction of amorphous phase was also obtained.SEM images of lightweight concrete samples showed that the structure ofCalcium Silicate Hydrates (CSH) started growing at the beginning of hydrationtime and continue to evolve into a more solid structure until the age of 28 days,where the compound has an important role to the mechanical properties such ascompressive strength. The study concluded that the pumice and rice husk ash isare amorphous silica-based material which has a lower density compared to otherconcrete forming material such as cement and sands. Both density and lightweight concrete compressive strength are determined by the ratio between pumiceand rice husk ash, in which the smallest ratio 8 resulted in the largest density andcompressive strength, which are 1890.5 kg/m3 and 23.2 MPa respectively at theage of 28 days. The study concluded that the best composition for lightweightconcrete samples was the following: PCC (1,00): Sand (1,00): ASP (0,05): BA(0,50) with a slump value of 8 cm resulted in the largest value of a ratio betweencompressive strength and density of 1285.;Research studies on the manufacture of lightweight concrete (LWC) usingpumice and rice husk ash (RHA) materials have been done. LWC samples weremade of pumice materials with a different mass fraction, while the cement, sand,and rice husk ash materials were keep fixed. It was found that there are two mainparameters that determine the mechanical properties of LWC which are densityand the water and cement ratio (w/c ratio). The main mechanical properties ofLWC sample is the power press. Samples with the largest volume fraction ofpumice (100%) resulted in lightest density (1389.6 kg/m3) and the smalleststrength of LWC (11.1 MPa). It was found that, the lower the mass fraction ofpumice in LWC samples, the higher the density values and compressive strengthwere obtained. This was caused by the high mas fraction value of pores, whichwere both open and closed pores. Scanning electron micorscopy (SEM) imagesfor the pumice showed that the there are a large number of regular and structuredpores extending deep inside the surface of the sample. It was observed that porespresent with pore size does not vary significantly but with the density of therelatively large number of pores, indicating pumice has a low mass density. TheXRD pattern of the lightweight concrete samples indicated that the samples weredominated by crystalline phases in which the quartz (SiO2) is the main phase anda small fraction of amorphous phase was also obtained.SEM images of lightweight concrete samples showed that the structure ofCalcium Silicate Hydrates (CSH) started growing at the beginning of hydrationtime and continue to evolve into a more solid structure until the age of 28 days,where the compound has an important role to the mechanical properties such ascompressive strength. The study concluded that the pumice and rice husk ash isare amorphous silica-based material which has a lower density compared to otherconcrete forming material such as cement and sands. Both density and lightweight concrete compressive strength are determined by the ratio between pumiceand rice husk ash, in which the smallest ratio 8 resulted in the largest density andcompressive strength, which are 1890.5 kg/m3 and 23.2 MPa respectively at theage of 28 days. The study concluded that the best composition for lightweightconcrete samples was the following: PCC (1,00): Sand (1,00): ASP (0,05): BA(0,50) with a slump value of 8 cm resulted in the largest value of a ratio betweencompressive strength and density of 1285., Research studies on the manufacture of lightweight concrete (LWC) usingpumice and rice husk ash (RHA) materials have been done. LWC samples weremade of pumice materials with a different mass fraction, while the cement, sand,and rice husk ash materials were keep fixed. It was found that there are two mainparameters that determine the mechanical properties of LWC which are densityand the water and cement ratio (w/c ratio). The main mechanical properties ofLWC sample is the power press. Samples with the largest volume fraction ofpumice (100%) resulted in lightest density (1389.6 kg/m3) and the smalleststrength of LWC (11.1 MPa). It was found that, the lower the mass fraction ofpumice in LWC samples, the higher the density values and compressive strengthwere obtained. This was caused by the high mas fraction value of pores, whichwere both open and closed pores. Scanning electron micorscopy (SEM) imagesfor the pumice showed that the there are a large number of regular and structuredpores extending deep inside the surface of the sample. It was observed that porespresent with pore size does not vary significantly but with the density of therelatively large number of pores, indicating pumice has a low mass density. TheXRD pattern of the lightweight concrete samples indicated that the samples weredominated by crystalline phases in which the quartz (SiO2) is the main phase anda small fraction of amorphous phase was also obtained.SEM images of lightweight concrete samples showed that the structure ofCalcium Silicate Hydrates (CSH) started growing at the beginning of hydrationtime and continue to evolve into a more solid structure until the age of 28 days,where the compound has an important role to the mechanical properties such ascompressive strength. The study concluded that the pumice and rice husk ash isare amorphous silica-based material which has a lower density compared to otherconcrete forming material such as cement and sands. Both density and lightweight concrete compressive strength are determined by the ratio between pumiceand rice husk ash, in which the smallest ratio 8 resulted in the largest density andcompressive strength, which are 1890.5 kg/m3 and 23.2 MPa respectively at theage of 28 days. The study concluded that the best composition for lightweightconcrete samples was the following: PCC (1,00): Sand (1,00): ASP (0,05): BA(0,50) with a slump value of 8 cm resulted in the largest value of a ratio betweencompressive strength and density of 1285.] |
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