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 community service activity is intended to provide knowledge updates to Building Engineering Vocational High School teachers regarding the operation of the Tekla Structures BIM, where Tekla Structures is one of the tools of BIM, especially 3D drawings, detailing and material quantity. The method used is to analyze the needs of partners, lectures, discussions, and demonstrations. The participants of the activity, apart from the Building Vocational High School teachers in Banyumas, were also attended by representatives of several Subject Course Teacher Conferences (MGMP) throughout Central Java. Based on the evaluation of the activities, as many as 88.7% of participants had understood the concept of BIM after participating in this activity, participants welcomed and enthusiastically related to the development of learning by always following technological developments, especially in the construction sector.
Kajian ini membahas karakteristik fisik dan mekanik komposoit semen limbah partikel bambu dan serat aren dengan variasi komposisi campuran untuk memperoleh formulasi empiris guna memprediksi sifat mekaniknya. Pembuatan dan pengujian benda uji dilakukan sesuai standar ASTM D 143 dengan 5 variasi komposisi jumlah campuran partikel bambu dan serat aren masing-masing 0%:100%; 25%:75%; 50%: 50%; 75%:25%; dan 100%: 0%; dengan kerapatan direncanakan 0,8 g/cm3. Variasi lainnya adalah ukuran limbah partikel bambu yaitu tertahan saringan 5 cm x 5 cm; 1 cm x 1 cm, 0,5 cm x 0,5 cm, dan 0,2 cm x 0,2 cm. Jumlah semen divariasikan dengan perbandingan bahan dan semen 1:2, 1:3, dan 1:4. Hasil kajian memperlihatkan bahwa perilaku sifat fisik terbaik diperoleh pada perbandingan bahan dan semen 1:4 dan ukuran partikel bambu 0,2 cm x 0,2 cm dan 0,5 cm x 0,5 cm. Kajian sifat mekanik menunjukkan tegangan lentur (MOR) balok/papan semen berkisar 4,77-6,59 MPa, dengan hasil terbesar pada komposisi balok semen campuran partikel bambu dan serat 50%:50% dengan ukuran partikel bambu 0,2 cm x 0,2 cm dan panjang serat aren 5 cm. Modulus elastisitas (MOE) balok semen tertinggi diperoleh pada campuraan partikel bambu dan serat aren 100%:0% dan ukuran partikel bambu 0,2 cm x 0,2 cm. Kandungan semen terbaik untuk MOE sebesar 2283,02 MPa didapat pada perbandingan bahan dan semen 1:3.
Corrosion rates in reinforced concrete can be detected by the amount of chloride ions present in concrete. This study aims to determine the effect of calcium stearate use on self compacting concrete on the infiltration of chloride ions. The calcium stearate content used is 0, 1, 5 and 10 kg per 1 m3 of self-compacting concrete (SCC). The concrete quality tested includes 20, 30 and 40 MPa. The parameters tested in this study were compressive strength and infiltration of chloride ions. Compressive strength specimen is in the form of cylinder 15 mm in diameter and 150 mm in height, while chloride ion infiltration specimen is in the form of cubes with sides of 150 mm. The results show that calcium stearate concrete with 10 kg / m3 of concrete when compared to normal concrete, the compressive strength decreases by -6.69%, 16.16% and 18.74% for concrete 20, 30 and 40 MPa respectively. Whereas the infiltration of chloride ions in concrete on 10 mm depth from the concrete surface was 0.153, 0.061 and 0.012% in the concrete of 20, 30 and 40 MPa. These infiltration of chloride ion in concrete 20, 30 and 40 MPa are lower around 287, 252, and 626% compared to concrete without calcium stearate.
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