Moh. Azhar
Abstrak :
[ABSTRAK
Telah dilakukan penelitian pembuatan beton ringan atau lightweight
concrete (LWC) menggunakan batu apug (BA) dan abu sekam padi (ASP).
Sampel beton ringan yang dibuat mengandung BA dengan fraksi berbeda, adapun
material semen, pasir, dan abu sekam padi volumenya dijaga tetap. Terdapat dua
parameter utama yang menentukan sifat mekanik sampel LWC masing-masing
adalah densitas sampel dan rasio air/semen (w/c). Sifat mekanik yang paling
utama dari LWC adalah kekuatan tekan. Pada campuran dengan fraksi volume
batu apung terbesar (100%) menghasilkan densitas dan kekuatan tekan paling
rendah masing-masing sebesar (1389,6 kg/m3 dan 11,1 MPa). Diketahui bahwa
makin rendah fraksi batu apung dalam sampel beton makin tinggi nilai densitas
dan kekuatan tekannya, disebabkan oleh tingginya nilai fraksi pori baik pori
terbuka maupun pori tertutup dalam sampel beton. Observasi terhadap fotomikro
SEM batu apung menunjukkan bahwa terdapat sejumlah besar pori dengan bentuk
memanjang ke bagian dalam dari permukaan sampel beton. Pori hadir dengan
kerapatan jumlah pori relatif besar serta dengan ukuran yang bervariasi. Fakta ini
menjelaskan mengapa batu apung besifat ringan karena memiliki densitas massa
yang rendah. Pola difraksi sinar X sampel beton ringan memperlihatkan dominasi
fasa kristalin diidentifikasi sebagai fasa quartz (SiO2). Namun dapat dipastikan
sampel beton ringan terdiri dari fasa campuran antara fasa kristalin dan dengan
sedikit fasa amorph.
Fotomikro SEM beton ringan menunjukkan bahwa senyawa Kalsium Silikat
Hidrat (CSH) mulai tumbuh pada waktu awal proses hidrasi dan terus
berkembang sampai umur beton mencapai umur hidrasi 28 hari yang ditandai
dengan sifat fisik yang padat dan peningkatan kekuatan beton. Dapat dipastikan
bahwa senyawa CSH ini memiliki peranan penting terhadap pengaturan sifat
mekanik seperti kekuatan tekan. Penelitian ini menyimpulkan bahwa batu apung
dan abu sekam padi adalah material berbasis silika amorph yang memiliki densitas
lebih rendah terutama dibandingkan dengan material pembentuk beton lainnya.
Baik densitas dan kekuatan tekan sampel beton ringan ditentukan oleh rasio antara
batu apung dan abu sekam padi. Ditemukan rasio terkecil BA/ASP yaitu 8
menghasilkan nilai densitas dan kekuatan tekan optimal, masing-masing pada usia
beton 28 hari sebesar 1891 kg/m3 dan 23 MPa. Komposisi beton ringan yang
terbaik 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 nilai
rasio antara kuat tekan dan densitas tertinggi adalah 1285.;
ABSTRACT
Research studies on the manufacture of lightweight concrete (LWC) using
pumice and rice husk ash (RHA) materials have been done. LWC samples were
made 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 main
parameters that determine the mechanical properties of LWC which are density
and the water and cement ratio (w/c ratio). The main mechanical properties of
LWC sample is the power press. Samples with the largest volume fraction of
pumice (100%) resulted in lightest density (1389.6 kg/m3) and the smallest
strength of LWC (11.1 MPa). It was found that, the lower the mass fraction of
pumice in LWC samples, the higher the density values and compressive strength
were obtained. This was caused by the high mas fraction value of pores, which
were both open and closed pores. Scanning electron micorscopy (SEM) images
for the pumice showed that the there are a large number of regular and structured
pores extending deep inside the surface of the sample. It was observed that pores
present with pore size does not vary significantly but with the density of the
relatively large number of pores, indicating pumice has a low mass density. The
XRD pattern of the lightweight concrete samples indicated that the samples were
dominated by crystalline phases in which the quartz (SiO2) is the main phase and
a small fraction of amorphous phase was also obtained.
SEM images of lightweight concrete samples showed that the structure of
Calcium Silicate Hydrates (CSH) started growing at the beginning of hydration
time 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 as
compressive strength. The study concluded that the pumice and rice husk ash is
are amorphous silica-based material which has a lower density compared to other
concrete forming material such as cement and sands. Both density and light
weight concrete compressive strength are determined by the ratio between pumice
and rice husk ash, in which the smallest ratio 8 resulted in the largest density and
compressive strength, which are 1890.5 kg/m3 and 23.2 MPa respectively at the
age of 28 days. The study concluded that the best composition for lightweight
concrete 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 between
compressive strength and density of 1285.;Research studies on the manufacture of lightweight concrete (LWC) using
pumice and rice husk ash (RHA) materials have been done. LWC samples were
made 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 main
parameters that determine the mechanical properties of LWC which are density
and the water and cement ratio (w/c ratio). The main mechanical properties of
LWC sample is the power press. Samples with the largest volume fraction of
pumice (100%) resulted in lightest density (1389.6 kg/m3) and the smallest
strength of LWC (11.1 MPa). It was found that, the lower the mass fraction of
pumice in LWC samples, the higher the density values and compressive strength
were obtained. This was caused by the high mas fraction value of pores, which
were both open and closed pores. Scanning electron micorscopy (SEM) images
for the pumice showed that the there are a large number of regular and structured
pores extending deep inside the surface of the sample. It was observed that pores
present with pore size does not vary significantly but with the density of the
relatively large number of pores, indicating pumice has a low mass density. The
XRD pattern of the lightweight concrete samples indicated that the samples were
dominated by crystalline phases in which the quartz (SiO2) is the main phase and
a small fraction of amorphous phase was also obtained.
SEM images of lightweight concrete samples showed that the structure of
Calcium Silicate Hydrates (CSH) started growing at the beginning of hydration
time 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 as
compressive strength. The study concluded that the pumice and rice husk ash is
are amorphous silica-based material which has a lower density compared to other
concrete forming material such as cement and sands. Both density and light
weight concrete compressive strength are determined by the ratio between pumice
and rice husk ash, in which the smallest ratio 8 resulted in the largest density and
compressive strength, which are 1890.5 kg/m3 and 23.2 MPa respectively at the
age of 28 days. The study concluded that the best composition for lightweight
concrete 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 between
compressive strength and density of 1285., Research studies on the manufacture of lightweight concrete (LWC) using
pumice and rice husk ash (RHA) materials have been done. LWC samples were
made 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 main
parameters that determine the mechanical properties of LWC which are density
and the water and cement ratio (w/c ratio). The main mechanical properties of
LWC sample is the power press. Samples with the largest volume fraction of
pumice (100%) resulted in lightest density (1389.6 kg/m3) and the smallest
strength of LWC (11.1 MPa). It was found that, the lower the mass fraction of
pumice in LWC samples, the higher the density values and compressive strength
were obtained. This was caused by the high mas fraction value of pores, which
were both open and closed pores. Scanning electron micorscopy (SEM) images
for the pumice showed that the there are a large number of regular and structured
pores extending deep inside the surface of the sample. It was observed that pores
present with pore size does not vary significantly but with the density of the
relatively large number of pores, indicating pumice has a low mass density. The
XRD pattern of the lightweight concrete samples indicated that the samples were
dominated by crystalline phases in which the quartz (SiO2) is the main phase and
a small fraction of amorphous phase was also obtained.
SEM images of lightweight concrete samples showed that the structure of
Calcium Silicate Hydrates (CSH) started growing at the beginning of hydration
time 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 as
compressive strength. The study concluded that the pumice and rice husk ash is
are amorphous silica-based material which has a lower density compared to other
concrete forming material such as cement and sands. Both density and light
weight concrete compressive strength are determined by the ratio between pumice
and rice husk ash, in which the smallest ratio 8 resulted in the largest density and
compressive strength, which are 1890.5 kg/m3 and 23.2 MPa respectively at the
age of 28 days. The study concluded that the best composition for lightweight
concrete 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 between
compressive strength and density of 1285.]
2015
D2054
UI - Disertasi Membership Universitas Indonesia Library
