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"Pengaruh substitusi terak baja sebagai agregat kasar pada kekuatan tekan dan korosi baja tulangan pada beton geopolimer berbahan dasar fly ash dalam air laut dan lingkungan hujan asam Nilai kuat tekan dievaluasi dengan mengukur beban maksimum yang dapat diterima menggunakan peralatan pengujian kompresi Kuat tekan tergantung pada beberapa faktor seperti waktu dan suhu curing serta proporsi pencampuran Kekuatan tekan beton geopolimer dengan substitusi terak baja lebih tinggi dibandingkan dengan beton geopolimer normal dengan agregat kerikil Nilai kuat tekan optimum ditemukan pada hari ketiga curing pada suhu 60oC untuk beton geopolimer dengan substitusi terak baja dan beton geopolimer normal Korosi tulangan dievaluasi dengan mengukur kepadatan arus korosi menggunakan polarisasi linear potensiostatik scan Laju korosi icorr baja tulangan dalam beton geopolimer dengan substitusi terak baja lebih tinggi dibandingkan dengan beton geopolimer normal tanpa terak baja dalam medium air laut Sedangkan dalam lingkungan hujan asam substitusi terak baja meningkatkan ketahanan korosi Laju korosi geopolimer beton dengan substitusi terak baja ditemukan lebih rendah dibandingkan dengan beton geopolimer normal Laju korosi sangat tinggi pada hari hari awal dan menurun seiring waktu.

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The effect of steel slag substitution as coarse aggregate on compressive strength and corrosion of reinforcing steel in fly ash based geopolymer concrete in seawater and acid rain environment was studied The compressive strength was evaluated by measuring maximum acceptable load using compression testing equipment The compressive strength depends on several factors such as time and temperature of curing and mixing proportion The compressive strength of geopolymer concrete with steel slag substitution is higher as compared to normal geopolymer concrete with gravel aggregate The compressive strength optimum was found in the third day curing at temperature 60oC for both of geopolymer concrete with steel slag substitution and normal geopolymer concrete The reinforcement corrosion was evaluated by measuring the corrosion current density using liner polarization potentiostatic scan The Corrosion rate icorr of reinforcing steel in geopolymer concrete with steel slag substitution were found to be higher as compared to normal geopolymer concrete without steel slag in seawater medium Whereas in acid rain environment steel slag substitution increase corrosion resistance Corrosion rate geopolymer concrete with steel slag substitution were found to be lower as compared to normal geopolymer concrete The corrosion rate is very high early days and decreases by time "

"The effect of steel slag substitution as coarse aggregate on compressive strength in fly ash based-geopolymer concrete was studied. The compressive strength was evaluated by measuring the maximum acceptable load using compression testing equipment. Compressive strength depends on several factors, such as time and temperature of curing and the mixing proportion. The compressive strength of geopolymer concrete with steel slag substitution was higher compared to geopolymer concrete with gravel aggregate. The optimum compressive strength was found on the third day of curing at a temperature of 60oC for both the geopolymer concrete with steel slag substitution and normal geopolymer concrete. Reinforcement corrosion was evaluated by measuring the corrosion current density using a linear polarization potentiostatic scan. The corrosion rate of reinforcing steel in geopolymer concrete with steel slag substitution was found to be higher compared to normal geopolymer concrete without steel slag in seawater medium, whereas in an acid rain environment, steel slag substitution increased corrosion resistance. The corrosion rate of geopolymer concrete with steel slag substitution was found to be lower compared to normal geopolymer concrete. The corrosion rate was found to be very high at an early stage and decreased with time."

"Kebijakan sistem zonasi digunakan dalam proses penyeleksian penerimaan peserta didik baru (PPDB) untuk jenjang pendidikan SMP dan SMA yang diselenggarakan oleh negara. Tujuan kebijakan ini sebagai upaya pemerintah dalam melakukan pemerataan pendidikan di Indonesia untuk menghapus stigma eklusivitas sekolah unggulan dan sekolah non-unggulan. Dalam pelaksanaan penerimaan peserta didik baru tahun 2017 dan tahun 2018 masih ditemukan tindak kejahatan; tindak jual-beli kursi, kasus pungutan liar dan kasus pemalsuan Surat Keterangan Tidak Mampu (SKTM) yang baru muncul sejak diterapkan PPDB sistem zonasi. Dalam penulisan ini menggunakan Routine Activity Theory untuk mengidentifikasi dan menganalisis bagaimana peluang membentuk beberapa kasus kejahatan dalam proses pelaksanaan PPDB. Pengumpulan data diperoleh dari berbagai sumber laporan dan berita, serta wawancara. Hasil penelitian ditemukan bahwa peluang kejahatan terbentuk akibat rentannya target, para pelaku yang termotivasi untuk melakukan tindak kejahatan dan lemahnya pengawasan yang cakap.

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The school zoning system policy is applied in the process of selecting new student admissions (PPDB) for the level of junior and senior high school education held by the state. The purpose of the school zoning system is one of the government efforts inequitable education in Indonesia to eliminating the stigma of exclusivity in schools. In the implementation of new student admissions in 2017 and 2018, crimes are still found; seat purchases, extortion, and relief letter for students from disadvantaged families (SKTM) Forgery that has emerged since the PPDB zoning system were implemented.

This writing is using the Routine Activity Theory to identify and analyze how opportunities form several criminal cases in the process of implementing PPDB. Data collection is obtained from various sources of reports and news, as well as an interview. The result found that chances of crime formed are due to the vulnerability of the targets, the motivated offenders who willing to commit crimes and lack of capable guardians."

"Korosi pada tulangan beton dapat terjadi akibat berbagai faktor, salah satunya adalah faktor lingkungan. Air laut merupakan salah satu lingkungan yang mempunyai dampak buruk terhadap beton bertulang. Salah satu cara yang dapat dilakukan dalam memperlambat laju korosi pada tulangan beton adalah dengan menambahkan zat inhibitor dalam komposisi beton yang membungkus tulangan. Akan tetapi penambahan inhibitor ini tentu akan berpengaruh terhadap mutu beton dan laju korosi. Kondisi inilah yang melatarbelakangi penelitian terhadap pengaruh inhibitor terhadap laju korosi dan mutu beton ekspos di air laut.Inhibitor yang diteliti pada penelitian ini adalah senyawa Nitrite dalam tiga konsentrasi, yaitu 70 ppm, 100 ppm, dan 130 ppm. Hal yang ditinjau dalam penelitian ini adalah kekuatan tekan beton dan laju korosinya. Pengkondisian perlakuan dalam penelitian ini dilakukan dengan cara merendam beton pada laut yang sebenarnya, dalam hal ini di Pelabuhan Kalijafat 5. Pengujian kuat tekan beton dilakukan pada kubus beton berukuran 15 x 15 x 15 cm3 pada umur 30, 60, 90 dan 180 hari. Pengujian laju korosi dilakukan pada beton silinder diameter 5 cm dan tinggi 15 cm pada umur 0 dan 90 hari.Dari penelitian ini didapatkan hasil kuat tekan beton di air laut pada umur 30, 60, 90 dan 180 hari, yaitu 70 ppm : 365,105 kg/cm2, 351,888 kg/cm2, 342,442 kg/cm2 dan 310,6 kg/cm2; 100 ppm : 360,29 kg/cm2, 322,927 kg/cm2, 296,906 kg/cm2 dan 281,15 kg/cm2; 130 ppm : 343,04 kg/cm2, 342,339 kg/cm2, 343,305 kg/cm2. Kuat tekan beton tanpa Inhibitor : 382,013 kg/cm2, 399,312 kg/cm2, 411,861 kg/cm2 dan 424,917 kg/cm2. Konsentrasi optimum inhibitor nitrtite adalah 130 ppm. Laju Korosi yang diperoleh pada penelitian ini di hari ke-0 dan 90 yaitu, beton normal : 0,26 mpy dan 0,352 mpy; tanpa inhibitor : 0,105 mpy dan 0,024 mpy; 70 ppm : 0,096 mpy dan 0,312 mpy; 130 ppm : 1,12 mpy dan 6,67 mpy.

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Corrosion in reinforced concrete occur as result of many factor, such as environment. Sea water in marine environment has destructive effect to reinforced concrete. Adding inhibitor as admixture in reinforced concrete is an action to reduce corrosion rate occur in steel reinforcement. However, use of inhibitor as admixture must influence the strength of concrete itself and corrosion rate. This condition appear as background in research of the effect of inhibitor to corrosion rate and exposed concrete at marine environment.

Inhibitor that used in this research is nitrite at three concentration, which are 70 ppm, 100 ppm, and 130 ppm. Object of this research is the compressive strength of concrete and corrosion rate. The way of treating concretes in this researchis by placing the concrete in actual marine environment which is placed in Kalijafat 5 Harbour. The compression test is done to cubical concrete dimension : 15 x 15 x 15 cm3 at 30, 60, 90 and 180 days age of concrete. Corrosion rate test is done to cylindrical concrete 5 cm of diameter and 15 cm of height at 0 and 90 days age.

The result of this research is compressive strength of concrete that exposed to sea water at age 30, 60, 90 and 180 days, which are 70 ppm : 365,105 kg/cm2, 351,888 kg/cm2, 342,442 kg/cm2 and 310,6 kg/cm2; 100 ppm : 360,29 kg/cm2, 322,927 kg/cm2, 296,906 kg/cm2 and 281,15 kg/cm2; 130 ppm : 343,04 kg/cm2, 342,339 kg/cm2, 343,305 kg/cm2. Without inhibitor : 382,013 kg/cm2, 399,312 kg/cm2, 411,861 kg/cm2 and 424,917 kg/cm2. Optimum concentration of inhibitor nitrite is 130 ppm. The result of this research is corrosion rate at age 0 and 90 days, which are normal concrete : 0,26 mpy and 0,352 mpy; without inhibitor : 0,105 mpy and 0,024 mpy; 70 ppm : 0,096 mpy and 0,312 mpy; 130 ppm : 1,12 mpy and 6,67 mpy."

"Material Baja Tulangan Sirip (BJTS) atau yang sering disebut baja ulir banyak digunakan dalam bidang konstruksi. Baja ulir ini pada umumnya digabungkan ke dalam beton sehingga dikenal beton bertulang. Penelitian ini dilakukan guna menganalisis laju korosi pada baja ulir untuk mengetahui sisa umur pakai baja tersebut. Pengujian penelitian ini meliputi struktur mikro, sifat mekanis dan laju korosi. Hasil analisa menunjukan bahwa baja ulir yang digunakan dalam kolom struktur gedung ditemukan adanya korosi. Akan tetapi laju korosi pada baja tersebut hanya bersifat pasif pada suhu kamar. Laju korosi pada baja ulir tertinggi sebesar 11,8116 mils per year dan sisa umur pakai tertinggi sebesar 76,66 tahun. Sehingga pengunaan baja ulir pada bidang konstruksi dapat digunakan lebih dari 70 tahun.

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Material Reinforcing Steel Bar Deform (BJTS) or called baja ulir is widely used in the construction field. Reinforcing steel is generally incorporated into the concrete so that reinforced concrete is known. This study was conducted to analyze the corrosion rate on reinforcing steel bar to the remaining life of the steel. Testing of the research includes the microstructure, mechanical properties and corrosion rate.

The analysis shows that the reinforcing steel bar used in the building structure column found corrosion. But the corrosion rate of steel is merely passive at room temperature. The corrosion rate on reinforcing steel biggest of 11,8116 mils per year and the biggest remaining life of 76,66 years. So that the use of reinforcing steel in the construction field can be used for more than 70 years."

"Penelitian ini dilakukan untuk mengetahui perilaku korosi pada baja tulangan dalam beton geopolimer berbahan dasar abu terbang serta daya tahan beton pada kondisi normal dan agresif (air laut) dengan membandingkannya terhadap beton konvensional dengan desain campur beton sama. Proses korosi dipercepat dengan pemberian potensial tinggi pada baja tulangan sehingga diperoleh hasil pengujian yang layak dalam waktu yang relatif singkat. Pada hari pertama pengujian, baja dalam beton geopolimer berada pada daerah korosi dengan potensial -0,293V; pH 7,2 di aquades dan -0,427V; pH 8,2 di air laut. Setelah 10 hari, baja tulangan dalam aquades berada di daerah pasif dengan potensial -0,183V; pH 10 sedangkan di air laut, baja berada di daerah korosi dengan potensial -0,327V dan pH 9. Namun demikian, baja tulangan pada beton konvensional di dalam aquades dan air laut berada pada daerah korosi dari hari pertama hingga hari ke-10. Pada hari pertama pengujian, baja berada pada potensial -0,529; pH 7,2 di aquades sedangkan di air laut, potensial baja -0,205V;pH 8,2. Setelah 10 hari, nilai potensial baja sekitar -0,543 V; pH 7,2 di aquades dan -0,319; pH 8,2 di air laut. Oleh karena itu, beton geopolimer memiliki ketahanan yang lebih baik terhadap korosi dibandingkan beton konvensional karena terjadi polikondensasi dari alumina dan silika membentuk cross linked aluminosilikat sehingga dapat menghambat difusi dari oksigen dan ion-ion agresif seperti ion klorida. Salanjutnya, kuat tekan beton geopolimer sebesar 45,3 Mpa lebih tinggi dibandingkan beton konvensional yaitu sekitar 39,49 Mpa dengan desain campur sama.

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The purpose of this research was to study corrosion behavior of steel bar in fly ash-based geopolymer concrete and durability in aquades and ASTM seawater compared to conventional concrete that has similar mix design. An accelerated corrosion by applying high potential on the steel bar was performed to obtain reasonable test results in a relatively short time. The potential and pH values of the steel bar were plotted on Pourbaix diagram for concrete immersed in aquades and seawater. For the first days, steel bar in geopolymer concrete in aquades and seawater located on corrosive area with potential values are -0,293V; pH 7,2 (aquades) and -0,427V; pH 8,2 (seawater). After 10 days, in aquades, steel on passive area with potential -0,183V; pH 10 whereas in seawater that has -0,327V; pH 9, steel on corrosive area. However, steel bar in conventional concrete immersed in aquades and seawater located on corrosive area from first day until 10 days. For the first days, potential values of steel bar are -0,529; pH 7,2 (aquadest) and -0,205V; pH 8,2 (seawater). After 10 days, potential value of steel are -0,543 V; pH 7,2 in aquades and -0,319; pH 8,2 in seawater. Thus, geopolymer concrete is better than conventional concrete in order to resist the corrosion of the steel bars because polycondensation of alumina and silikat in geopolymer forming cross linked aluminosilikat that can impede diffusion of oxygen and aggressive species as chloride ions. Furthermore, for the same mix design, geopolymer concrete has higher compressive strength than conventional concrete, i.e. 45,3 Mpa and 39,49 Mpa respectively."

"Terak merupakan hasil sampingan dari proses pengolahan mineral yang masih dapat dimanfaatkan seperti contohnya pada bidang konstruksi. Penelitian ini bertujuan untuk mengetahui karakteristik beton dari Ordinary Portland Cement (OPC) dengan campuran terak terhadap ketahanan korosi baja tulangan berdasarkan metode Electrochemical Impedance Spectroscopy (EIS) dan Linier Polarization. Penelitian ini menggunakan terak akhir timah dan terak akhir nikel yang dicampurkan dengan OPC masing-masing sebanyak 0%, 30%, dan 40% dari berat total semen didalam beton. Rasio terak timah dan terak feronikel didalam beton adalah 1:1. Beton  dilakukan proses curing selama 28 hari lalu direndam di dalam larutan NaCl 3.5% selama 1 bulan sebelum pengujian korosi. Hasil menunjukkan baja di dalam campuran 40% terak memiliki ketahanan korosi yang paling baik dibandingkan dengan dua sampel.

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Slag is side product of mineral processing that still beneficial such as in construction sector. This research intend to study about characteristics of Ordinary Portland Cement (OPC) concrete with slag mixture concrete against corrosion resistance of steel reinforcement embedded inside the concrete with Electrochemical Impedance Spectroscopy (EIS) and Linear Polarization Method. There are two kind of slag used in this research, tin slag and ferronickel slag, mixed to OPC with many percentage that is 0%, 30%, and 40% from weight total of cement inside concrete. Ratio of tin slag and ferronickel inside the concrete is 1:1. Concrete has 28 days of curing time then concrete immersed in NaCl 3.5% solution for one month before  corrosion testing. Result shows steel that embedded in concrete with 40% slag mixture has better corrosion resistance."

"Korosi menjadi penyebab utama rusaknya suatu struktur yang terbuat dari beton dengan tulangan baja. Penggunaan beton geopolimer terbukti dapat meningkatkan ketahanan tulangan baja terhadap serangan korosi, namun perlu dilakukan penelitian lebih lanjut untuk meningkatkan ketahanan korosi baja tulangan dalam beton, dengan tetap memperhatikan aspek lingkungan. Pada penelitian ini dilakukan substitusi kaca yang berasal dari botol bekas, sebagai agregat kasar dalam beton geopolimer. Pengujian ini dilakukan dengan merendam beton ke dalam larutan NaCl 3,5 % selama 31 hari, perilaku korosi tulangan baja dalam beton geopolimer diamati dengan metode polarisasi tahanan linier dan ekstrapolasi tafel. Hasil pengujian pada saat mencapai hari 31, menunjukan bahwa substitusi agregat kasar menggunakan kaca tidak memperbaiki ketahanan beton geopolimer terhadap korosi. Dimana, tahanan polarisasi baja dalam beton geopolimer dengan agregat kaca adalah 2935 Ω, lebih rendah dibanding nilai tahanan tulangan baja dalam beton geopolimer dengan agregat batu yakni 5235 Ω. Sedangkan laju korosi tulangan baja pada beton geopolimer dengan agregat kaca adalah 5,00 x 10-3 mm/tahun , lebih tinggi dibanding tulangan baja dalam beton dengan agregat batu yaitu 2,35 x 10-3 mm/tahun. Analisa komposisi larutan rendam dilakukan menggunakan metoda Atomic Absorbance Spectroscopy. Awalnya, larutan NaCl 3,5% memiliki kadar natrium senilai 13770 μm/ml. Usai masa perendaman beton, larutan rendam milik beton dengan agregat batu memiliki kandungan natrium 2252 μm/ml. Nilai tersebut lebih tinggi dibandingkan dengan kadar natrium larutan rendam beton dengan agregat kaca yaitu 1910 μm/ml. Hal ini mengindikasikan bahwa beton geopolimer dengan agregat kaca lebih mudah menyerap unsur dari luar lingkungan ke dalam beton.

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Corrosion is major cause damage to structure made of concrete with steel reinforcement. Using geopolymer concrete will increase the resistance of steel reinforcement against corrosion attack, further research needs to be done to improve the corrosion resistance of steel reinforcement, in regard to environmental aspects. In this research, waste glass is used as coarse aggregate in geopolymer concrete. Test was carried out by immersing concrete into 3,5% NaCl solution for 31 days, corrosion behavior of reinforcing steel in geopolymer concrete observed by linear polarization resistance and tafel extrapolation method. Test result on 31-day, showed that substitution of coarse aggregate with waste glass doesn?t improve the corrosion resistance of reinforce steel on geopolymer concrete. Which, polarization resistance value of steel reinforcement on geopolymer concrete with glass aggregate is 2935 Ω, less than polarization resistance value of steel reinforcement on geopolymer concrete with stone aggregate is 5235 Ω . On the other hand corrosion rate of steel reinforcement in geopolymer concrete with glass aggregate is 5,00 x 10-3 mm/year, were found to be higher than reinforcement steel on geopolymer concrete with stone aggregate that is 2,35 x 10-3 mm/year . Analysis of immersion solution composition were performed using Atomic Absorbance Spectroscopy method. Initially, the NaCl 3,5% solution, have sodium content worth of 13770 μm/ml. After immersion period, immersion solution belongs to concrete with stone aggregate has a sodium content 2252 μm/ml. These value is higher than the natrium content from immersion solution of concrete with glass aggregate which is 1910 μm/ml. This result indicates that geopolymer concrete with glass aggregate more easily absorb elements from the environment into the concrete."

"[ ABSTRAK Kaca merupakan sumber silika amorphous yang baik serta memiliki komposisi kimia dan reaktivitas yang tepat untuk melakukan reaksi Pozzolan. Sehingga muncul lah ide untuk menggunakan kaca sebagai agregat kasar pada beton. Pada penelitian ini, sampel yang dibuat adalah dua jenis beton, yaitu Portland dan Geopolimer dengan variasi substitusi kaca sebanyak 0%, 25%, 50%, 100%. Pengujian yang dilakukan adalah uji tekan dan pengamatan foto makro. Komposisi beton, sejarah perlakuan, dan suhu curing memberi pengaruh signifikan pada nilai kuat tekan yang dihasilkan. Kesimpulan yang didapatkan adalah beton Portland dan beton geopolimer dengan substitusi kaca sebesar 50% memiliki kuat tekan tertinggi, dan pasta geopolimer dapat melekat pada kaca namun pasta semen tidak.

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ABSTRACT

Glass are good source of amorphous silica and it also has good chemistry composition and precise reactivity to make Pozzolan reaction. So there was an idea to use glass as coarse aggregate in concrete. In this research, two types of concrete will be made, which are Portland concrete and geopolymer concrete with variation of waste glass substitution as much as 0%, 25%, 50%, 100%. The conducted tests are pressure test and macro photos observations. Concrete composition, treatment history, and curing temperature gave significant influence on their compressive strength. The conclusions are both portland and geopolymer concrete with 50% waste glass substitution has the highest compressive strength, and geopolymer paste could adhered to glass but cement paste could not.;Glass are good source of amorphous silica and it also has good chemistry composition and precise reactivity to make Pozzolan reaction. So there was an idea to use glass as coarse aggregate in concrete. In this research, two types of concrete will be made, which are Portland concrete and geopolymer concrete with variation of waste glass substitution as much as 0%, 25%, 50%, 100%. The conducted tests are pressure test and macro photos observations. Concrete composition, treatment history, and curing temperature gave significant influence on their compressive strength. The conclusions are both portland and geopolymer concrete with 50% waste glass substitution has the highest compressive strength, and geopolymer paste could adhered to glass but cement paste could not.;Glass are good source of amorphous silica and it also has good chemistry composition and precise reactivity to make Pozzolan reaction. So there was an idea to use glass as coarse aggregate in concrete. In this research, two types of concrete will be made, which are Portland concrete and geopolymer concrete with variation of waste glass substitution as much as 0%, 25%, 50%, 100%. The conducted tests are pressure test and macro photos observations. Concrete composition, treatment history, and curing temperature gave significant influence on their compressive strength. The conclusions are both portland and geopolymer concrete with 50% waste glass substitution has the highest compressive strength, and geopolymer paste could adhered to glass but cement paste could not.;Glass are good source of amorphous silica and it also has good chemistry composition and precise reactivity to make Pozzolan reaction. So there was an idea to use glass as coarse aggregate in concrete. In this research, two types of concrete will be made, which are Portland concrete and geopolymer concrete with variation of waste glass substitution as much as 0%, 25%, 50%, 100%. The conducted tests are pressure test and macro photos observations. Concrete composition, treatment history, and curing temperature gave significant influence on their compressive strength. The conclusions are both portland and geopolymer concrete with 50% waste glass substitution has the highest compressive strength, and geopolymer paste could adhered to glass but cement paste could not.;Glass are good source of amorphous silica and it also has good chemistry composition and precise reactivity to make Pozzolan reaction. So there was an idea to use glass as coarse aggregate in concrete. In this research, two types of concrete will be made, which are Portland concrete and geopolymer concrete with variation of waste glass substitution as much as 0%, 25%, 50%, 100%. The conducted tests are pressure test and macro photos observations. Concrete composition, treatment history, and curing temperature gave significant influence on their compressive strength. The conclusions are both portland and geopolymer concrete with 50% waste glass substitution has the highest compressive strength, and geopolymer paste could adhered to glass but cement paste could not., Glass are good source of amorphous silica and it also has good chemistry composition and precise reactivity to make Pozzolan reaction. So there was an idea to use glass as coarse aggregate in concrete. In this research, two types of concrete will be made, which are Portland concrete and geopolymer concrete with variation of waste glass substitution as much as 0%, 25%, 50%, 100%. The conducted tests are pressure test and macro photos observations. Concrete composition, treatment history, and curing temperature gave significant influence on their compressive strength. The conclusions are both portland and geopolymer concrete with 50% waste glass substitution has the highest compressive strength, and geopolymer paste could adhered to glass but cement paste could not.]"