This work aims to study the effect of Ca(C 18 H 35 O 2 ) 2 (calcium stearate) on the properties of concrete by using Portland composite cement (PCC) and fly ash as binders. The calcium stearate content used in the concrete here consists of 0, 1, 5, and 10 kg per m 3 of concrete volume, or alternatively, 0 to 2.85% by the weight of cement. We have performed several tests for each of the contents, namely, compressive strength, water absorption, chloride ion infiltration, and accelerated corrosion tests. According to the testing, we have found that with the addition of calcium stearate at 1 kg/m 3 in self-compacting concrete (SCC) with 10% fly ash, the mechanical and physical properties of SCC can be improved significantly when compared to the SCC without fly ash and calcium stearate, resulting in a stable compressive strength, lower water absorption, lower chloride ion infiltration, and lower degree of corrosion attack.Materials 2020, 13, 1394 2 of 16 calcium silicate hydrate mineral referred to as C-S-H (tobermorite) [9]. Calcium hydroxide itself is one of the compounds formed when tricalcium silicate (C3S), dicalcium silicate (C2S), or tricalcium aluminate (C3A) reacts with water (H 2 O). The use of fly ash in concrete as a substitute for cement further increases the amount of C-S-H/calcium silicate hydrate (tobermorite) formed during the cement hydration process. It can reduce cement the consumption by 3.2-5 kg·m −3 ·MPa −1 [10]. In the process of cement production, millions of tons of CO 2 gas (a pollutant) is released because of combustion to make clinker. Reducing cement consumption in concrete consequently decreases the CO 2 emissions. Besides that, the appearance of fly ash in concrete also raises the alkalinity of concrete [11]. The higher the alkalinity of concrete, the greater the passive layer protected steel bar in concrete is from corrosion attack.Not only additives such as fly ash, slag, and silica fumes, but superplasticizers such as water reducers [12] in concrete also can reduce the capillaries and pores [13] in concrete. Although the water/cement ratio used in concrete is very small, the workability of fresh concrete remains good, and this is easily maintained by adding a superplasticizer to the concrete [14]. Because of the low water/cement ratio used, autogenous shrinkage is reduced. Other effects include increasing the elastic modulus [15] and raising the anti-carbonation of the concrete [16].A large contact angle makes it more difficult for water to seep into concrete [17]. As a result, the water absorption of concrete also drops significantly. Furthermore, in general, chloride ions penetrate into concrete along with water because of the greater contact angle. Automatically, concrete-containing large silica particles are more resistant to corrosion attack. On the contrary, in concrete made with the addition of a water-entraining agent [18], chloride ions enter into concrete more easily, especially in young concrete [19,20]. Corrosion attack on the concrete reinforcement surface causes cracks ...

This work investigates the effect of calcium stearate (Ca(C18H35O2)2) on concrete shrinkage behaviors by using experimental testing. The test specimens are cubes with each dimension given as 100 × 100 × 285 mm for shrinkage tests and cylinders with 150 mm diameter and 300 mm height for compressive strength tests. The calcium stearate with fractions of 0, 0.1, 0.2, and 0.3% from the weight of cement are used in the tests. The results showed that the shrinkage occurred in amounts of 0.079, 0.062, 0.065, and 0.060 mm for the specimens containing calcium stearate of 0, 0.1, 0.2, and 0.3%, respectively. Moreover, we also perform shrinkage modelling to explore a possibility to incorporate the calcium stearate fraction into the standard concrete shrinkage model. There are three well-known shrinkage models used here, i.e., the Sakata, the Japan Standard and the Bazant-Baweja models, where only the latter one is capable to capture our experimental results very well for different fractions of calcium stearate.

The destructive force of the tsunami could induce a considerable amount of casualties, infrastructures, and properties. One of the large tsunamis in Indonesia is 2006 South of Java Tsunami. There were 664 fatalities, 498 injured, 55 million dollars in losses, and 1623 homes damaged. Simulations of flow depth and run-up of the 2006 tsunami on Widarapayung Beach have never been conducted. Although they can be used as a basis for determining tsunami hazard zones. The method that might be used for tsunami impact analysis is tsunami waves modeling by considering the focal mechanism. The aims of this research are to determine the run-up height and flow depth of the 2006 tsunami on Widarapayung Beach. The calculations of modeling were performed using COMCOT numerical model. It operates calculations by solving shallow water equations in both linear and non-linear equations. Using this model, the generation and propagation of tsunami in a multi-grid system could be simulated. The result of the simulations on three different models depicts that the maximum run-up height on Widarapayung Beach is 3 to 3.8 m. The flow depth result from the three different models also suggests vulnerable areas up to 1 km from the shoreline.

Abstrak-Telaga Tirta Marta terletak di Desa Karangcegak Purbalingga. Telaga ini dibentuk oleh satu titik keluran air tanah di permukaan dengan debit yang cukup tinggi. Selain itu terdapat titik-titik keluaran air tanah lain yang membentuk kelurusan di sepanjang kaki bukit. Keberadaan telaga ini juga menarik karena berada pada tatanan geologi yang lebih besar, yaitu Gunungapi Slamet. Publikasi dari hasil penelitian pendahuluan ini bertujua nmenganalisis faktor-faktor geologi yang mengontrol kemunculan mata air Telaga Tirta Marta. Penelitian pendahuluan ini menggunakan beberapa metode penelitian, yaitu: studi pustaka, survei lapangan dan kompilasi data lapangan, peta SRTM, dan geologi regional. Studi pustaka dilakukan untuk mendapatkan informasi awal terkait geologi lokasi penelitian. Survei lapangan dilakukan untuk mendapatkan data geologi berupa informasi geomorfologi, litologi dan struktur geologi serta karakteristik mata air Telaga Tirta Marta. Kompilasi berbagai data termasuk peta SRTM dan geologi regional dilakukan untuk mendapatkan informasi saling melengkapi dari berbagai data. Kajian pendahuluan ini memperlihatkan beberapa faktor geologi yang mengontrol kemunculan mata air Telaga Tirta Marta. Faktor-faktor tersebut, adalah: morfologi lokasi telaga yang terletak di kaki Gunungapi Slamet, jenis litologi yang berupa perlapisan lava dan lava vesikuler, dan struktur geologi yang berkembang di lokasi tersebut.Kata kunci-Telaga Tirta Marta, Gunungapi Slamet, karakteristik mata air.Abstract-Tirta Marta Lake is located in Karangcegak Village, Purbalingga district. This lake is formed by a single point of water discharge at the surface with a high discharge. There are other groundwater output points forming the straightness along the foot of the hill. The existence of this lake is also interesting because of this lake is in a larger geological configuration, namely Slamet Volcano. Publication of this preliminary research aims to analyze the geological factors that control the emergence of Tirta Marta springs. This study uses several research methods: literature study, field survey and field data compilation, SRTM maps, and regional geology. literature study was conducted to obtain preliminary information related to geology of research location. Field surveys were conducted to obtain geological data in the form of geomorphological information, lithology and geological structures and characteristics of Tirta Marta Lake waters. Compilations of various data including SRTM maps and regional geology were conducted to obtain complementary information from entire data. This preliminary study shows several geological factors that control the emergence of the Tirta Marta Lake spring. These factors are: the morphology of the lake that located at the foot of Mount Slamet, the type of lithology in the form of plated or stratified lava and vesicular lava, and the geologic structure which exists in that location.. Keywords-TirtaMarta Lake, Slamet Volcano, characteristic mata air. I. PENDAHULUANAir tanah sebagai sumberdaya alam yan...

<p>Longsoran Gunung Pawinihan di Kabupaten Banjarnegara, merupakan longsoran yang mengakibatkan korban jiwa cukup banyak yaitu sekitar 80 orang meninggal. Longsoran tersebut terjadi pada breksi volkanik Formasi Jonggrangan yang berumur Kuarter. Kondisi yang diteliti adalah terbentuknya bidang gelincir pada zona pelapukan 4 dimana komposisi batuan sebagian besar sudah mengalami pelapukan dengan persentase tanah lebih besar dari mineral utama.  Metode yang digunakan adalah klasifikasi zona pelapukan berdasarkan British Standard untuk mendeleniasi zona pelapukan breksi, kemudian analisis petrografi pada zona pelapukan yang berbeda. Hasil yang didapatkan adalah adanya perubahan komposisi mineral utama menjadi material tanah. Perubahan yang terjadi adalah adanya perubahan mineral utama seperti plagioklas menjadi mineral lempung, perubahan yang terjadi pada bagian luar mineral utama. Pada zona pelapukan 4 mineral oksidasi dan lempung mulai berkembang, sehingga komposisi mineral utama dan mineral sekunder utama hampir seimbang. Bidang gelincir longsoran terjadi pada zona ini, sehingga dapat dikatakan bidang gelincir terjadi pada zona 4 dimana terjadi perubahan mineral utama menjadi mineral sekunder yang cukup signifikan.</p><p><strong><em>Kata Kunci</em></strong>: <em>Debris slide</em>, zona pelapukan, bidang gelincir</p>