Increasing concrete strength is one of the main necessities of concrete technology. For more than the last 20 years, high strength concretes with compressive strength ranging from 50 MPa up to 140 MPa have been used worldwide in high rise buildings and bridges with long spans, or buildings in aggressive environments. But in Indonesia high strength concretes possesses maximum compressive strength of 60 MPa. The properties of concrete are affected by cementitious matrix, aggregate, and the transition zone between these two phases. Reducing the water-cement ratio and the addition of pozzolanic admixtures like fly-ash are often used to modify the microstructure of the matrix and to optimise the transition zone. The reduction of the water-cement ratio results in a decrease in porosity and refinement of capillary pores in matrix, but flowing ability of the concrete will also decrease so that it can’t be workable. Then it workablity can be improve by the use of a superplastisizer. The method used refers to the planning of normal concrete, which is contained in the SK-SNI 03-2834-1992. The results showed that superplastisizer with doses of more than 2% of the cement paste does not increase the flowing ability of the paste anymore. For all the rest of the experiments, the superplastisizer dosage was determined about 2 % of the powder mass. The first tests showed a good workability of the fresh concrete and a good self compacting ability with the silicafume dosage of 10 % of the powder mass. The interest in reducing costs for increasing the concrete strength, can be successfully achieved in this research.
The purpose of this research is to utilize pumice waste as one of the constituent materials of lightweight concrete. Indonesia, as an archipelagic country, has produced coral pumice waste scattered throughout the country. It is expected that by utilizing pumice waste, lightweight and environmentally friendly concrete may be produced. The tests carried out consisted of three series to examine the effect on the composition of light aggregate (series 1), the effect of light aggregate size (series 2), and the effect of the water to binder ratio (series 3). The composition of light aggregate as a substitute for coarse aggregate by 25%, 50%, 75%, and 100%, with a maximum aggregate size of 20 mm and water to binder ratio of 0.50. In the second series, the maximum size of lightweight aggregate is 9.5 mm, 16 mm, 20 mm, and 25 mm, using 100% lightweight aggregate with water to binder ratio of 0.50. In the third series, the water to binder ratio is varied 0.46, 0.48, and 0.50. A slump test was conducted to check the workability of fresh concrete, while the hardened properties test consisted of compressive strength and mass density. The results of the tests show that using a larger amount of lightweight aggregate reduces compressive strength. The variation of the maximum size of lightweight aggregate shows a pattern that the larger the aggregate size produces lower the compressive strength. The decrease in compressive strength also occurs in concrete with high water to binder ratio.
This study discusses the results of the rapid assessment of school buildings in Lombok after an earthquake occurs. The earthquake in July 2018 with a high enough intensity caused a lot of damage to the building. The earthquake including the school building affected the entire area of Lombok Island. This study assessed 15 school buildings on Lombok Island. School samples were taken randomly from several districts that were rocked by the earthquake. The results showed that school buildings in all locations were part of a Non-Engineered Building where there were no results of analysis of earthquake resistant buildings. Overall, the condition of the building is categorized as being moderately damaged with non-structural components such as walls not having good connections with columns and beams. In addition, the structure and attributes of the roof are also damaged by a high percentage. In some buildings, it still does not follow good structural rules so that it is very dangerous for building users in the event of a large earthquake. Improvements using the retrofitting method are one of the most recommended ways to improve the performance of buildings that have mild and moderate damage.
Abstrak: Beton merupakan salah satu material konstruksi yang paling banyak digunakan baik di dunia maupun di Indonesia. Bahan penyusun beton yang terdiri dari semen, air, agregat halus dan agregat kasar sangat mudah diperoleh. Pada penelitian ini memanfaatkan limbah bangunan sebagai material recycle yang dapat dimanfaatkan sebagai material penyusun beton. Bata ringan merupakan salah satu material yang digunakan untuk emngisi dinding sebagai komponen non-struktural. Limbah bata ringan yang sudah tidak digunakan dimanfaatkan kembali sebagai bahan tambah penyusun beton. Pada penelitian ini terdiri dari dua pemeriksaan utama yaitu limbah bata ringan sebagai agregat kasar dengan variasi ukuran maksimal agregat yaitu 16 mm, 22,4 mm dan 25 mm. sedangkan pemeriksaan kedua yaitu limbah bata ringan sebagai pengganti semen dengan variasi campuran sebesar 5%, 10% dan 15% dan berat binder. Pengujian sifat beton yang dilakukan terdiri dari slump test dan kuat tekan. Slump test digunakan untuk memeriksa workability beton segar sedangkan kuat tekan digunakan untuk memeriksa kapasitas tekan nya. Melalui penelitian ini diharapkan dapat memanfaatkan limbah konstruksi secara optimal dan dapat digunakan kembali sebagai material penyusun beton. Hasil penelitian menunjukkan bahwa agregat kasar limbah bata ringan dengan variasi ukuran maksimal 16 mm memperoleh kuat tekan tertinggi. Sedangkan pada pemanfaatan limbah bata ringan sebagai material pengganti semen menghasilkan kuat tekan tertinggi dengan variasi 5%.Kata-kata kunci: limbah bata ringan, agregat kasar, kuat tekan, recycle materialsAbstract: Concrete is one of the most widely used construction materials both in the world and in Indonesia. Concrete constituent materials consisting of cement, water, fine aggregate and coarse aggregate are very easy to obtain. In this study, using building waste as a recycle material that can be used as a concrete constituent material. Lightweight brick is one of the materials used to fill walls as a non-structural component. Light brick waste that is no longer used is reused as an added material for making concrete. This study consisted of two main examinations, namely lightweight brick waste as coarse aggregate with a maximum size variation of 16 mm, 22.4 mm and 25 mm. while the second examination was light brick waste as a substitute for cement with a mixture variation of 5%, 10% and 15% and the weight of the binder. The test of concrete properties consisted of slump test and compressive strength. Slump test is used to check the workability of fresh concrete while the compressive strength is used to check its compressive capacity. Through this research, it is hoped that construction waste can be utilized optimally and can be reused as a concrete constituent material. The results showed that the coarse aggregate of lightweight brick waste with a maximum size variation of 16 mm obtained the highest compressive strength. While the use of lightweight brick waste as a cement substitute material produces the highest compressive strength with a variation of 5%.Keywords: lightweight brick waste, coarse aggregate, compressive strength, recycle materials
Penelitian ini membahas pengaruh dari perawatan beton menggunakan air laut dan air sungai terhadap karakteristik beton. Tujuan dari penelitian ini untuk menjelaskan pengaruh dari jenis air pada perawatan beton, khususnya pada beton yang digunakan yang berhubungan langsung dengan air. Pada penelitian ini menggunakan tiga jenis produk semen yaitu Holcim, Tiga Roda dan Gresik dengan total 12 variasi dan 108 benda uji berbentuk silinder berdiameter 15 cm dan tinggi 30 cm. Seluruh variasi menggunakan standar mix design yang sama dengan 6 variasi menggunakan perbedaan jumlah superplasticizer dan 6 variasi menggunakan bahan tambah fly ash. Pengujian yang dilakukan berupa pemeriksaan workabilitas, kuat tekan dan nilai penyerapan. Hasil pada pengujian ini menunjukkan bahwa nilai workabilitas pada beton menggunakan superplasticizer lebih baik dibandingkan beton menggunakan bahan tambah fly ash. Hasil kuat tekan menunjukkan bahwa seluruh benda uji dengan perawatan air laut lebih tinggi dibandingkan dengan beton menggunakan perawatan air sungai. Sedangkan nilai penyerapan menunjukkan bahwa pada umur 28 hari dengan menggunakan air laut menghasilkan nilai yang lebih tinggi dibandingkan perawatan menggunakan air sungai.
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