Effect of Chemical Composition of Fine Aggregate on the Frictional Behavior of Concrete–Soil Interface under Sulfuric Acid Environment

Through direct shear tests, this paper aimed to research the effect of fine marble aggregate on the shear strength and fractal dimension of the interface between soil and concrete corroded by sulfuric acid. More realistic concrete rough surfaces than the artificially roughened surfaces were formed by immersing four concrete plates in plastic buckets filled with sulfuric acid for different periods of time. The sand was adopted to imitate the soil. 3D laser scanner was employed to obtain the digital shapes of concrete plates subjected to sulfuric acid, and the rough surfaces were evaluated by fractal dimension. Large direct shear experiments were performed to obtain the curves of the interface shear stress and shear displacement between sand and corroded concrete plate. The method of data fitting was adopted to calculate the parameters of shear strength (i.e., friction angle and the cohesive) and the parameters of the Clough–Duncan hyperbolic model. The results indicated that as the corrosion days increased, the surface of the concrete plate became rougher, the surface fractal dimensions of the concrete corroded by sulfuric acid became bigger, and the interface friction angle became greater. The friction angle of the interface and the fractal dimensions of the surface of the concrete plate containing crushed gravel and marble sand were smaller than that of the concrete plate containing crushed gravel and river sand.

Short-Term Deformation Model of High-Performance Concrete Plate Based on Surrounding Temperature

The relationship between surrounding temperature and deformation behaviour of one full scale concrete plate with compressive strength of 60 MPa was presented in this paper. This research was done in Indonesia. Indonesia presents humid tropical weather. A specimen measuring 3.00m × 1.60m × 0.15m was used. Deformation was obtained by using four embedded vibrating wire strain gauges. The range observation is held between 7 to 28 days. The peaks of deformation follow peaks of surrounding temperature. Some deformation peaks time occur after surrounding temperature peak time, it is called as delay time. As a result, there is a linear relationship between temperature and deformation. The relationship was influenced by a factor which presented its position and delay time. The average error of this model is less than 15% at the age range of 7 until 14 days, and less than 50% at the age range of 15 - 28 days.

Subdomain integration method of electrical resistance tomography for multiple flaws detection in cementitious materials

Electrical Resistance Tomography (ERT) has been widely used for detecting cementitious materials with one type of flaw. To extend the ERT for multi-flaws detection in a larger concrete plate, this paper develops a subdomain integration method. The adjacent driver pattern and absolute imaging scheme of ERT are adopted to reconstruct the inner electrical conductivity field of a concrete specimen which contains three different inclusions, namely, a copper bar, a piece of plexiglass, and a drop of saline solution. The feasibility of subdomain integration method for multiple flaws detection in cementitious materials is analyzed by theoretical analyses of the equipotential line density and the image quality evaluation indicator. The concrete specimen is divided into four, nine, and 16 subdomains for detection. The image reconstruction results obtained by the subdomain detection method are compared with each other, and with the results of a global detection method. Results indicate that the effective area of subdomain largely relies on the density of equipotential lines, as well as the measurement errors. Subdomain integration method is effective in detecting a relatively large cementitious component with multi-flaws.

PLANNING EVALUATION OF RIGID PAVEMENT’S THICKNESS ON INTERSECTION OF A ROAD SEGMENT OF SIKUI KM. 34 NATIONAL ROAD STA. 0+000 S/D 0+300 EAST BARITO DISTRICT

East Barito is one district that has a variety of natural resources such as agriculture and mining, Sikui KM of National Highway 34 is one of the roads that used to be accessed by one party mobilization of existing mines in Central Kalimantan. But on the other hand, the national road Sikui KM 34 is also used for connecting roads between provinces or cities. Based on the above actual national roads not intended for large-laden vehicles.Path planning is aimed to obtain a rigid pavement thickness based on the Pavement Design Manual Nomor 02/M/BM/2017 which controlled by “Pedoman Perencanaan Perkerasan Jalan Beton Semen Pd T-14-2003” and calculating the budget plan on the intersection of a road segment of Sikui KM 34 national road, East Barito disctrict.On the planning of rigid pavement’s thickness by using “Manual Desain Perkerasan Jalan Nomor 02/M/BM/2017” it is found that the concrete plate layer = 28,5 cm; LMC base layer = 10 cm; drainage layer = 15 cm and by using “Pedoman Perencanaan Perkerasan Jalan Beton Semen Pd T-14-2003” also found that the concrete plate layer = 21 cm; base layer = 15 cm. After that, on the existing condition obtained concrete plate layer = 30 cm; K-125 concrete layer = 10 cm. Then, it is found that the efficient pavement’s thickness which taken by using “Pedoman Perencanaan Perkerasan Jalan Beton Semen Pd T-14-2003” is more efficient rather than the existing condition. Moreover, this thesis also discusses the budget plan on the intersection of a road segment of Sikui Km. 34, East Barito district.

Comparative evaluation of concrete sand-control fences used for railway protection in strong wind areas

Concrete-plate fences have been widely adopted for windblown sand control and mitigation along railways. However, the inclination angles of inserting the concrete plate with respect to the vertical direction, i.e., straight or obliquely inserted concrete plates (SIP or OIP), significantly influence the efficiency of sand-control. This study performs a comparative evaluation of the SIP and OIP sand-control fences using wind tunnel testing and field monitoring data collected from the Lanzhou–Wulumuqi High-Speed Railway Project. The results show that the fence’s ability to reduce the wind speed and the sand-retaining efficiency gradually weakens with the increasing wind speed. Compared with the SIP fence, the OIP fence has a better wind speed reduction capability, stronger ability to capture fine particles below the top of the fence; it is more efficient for sand-retaining and induces stronger eddy intensity. Generally, the wind tunnel test and field monitoring results are consistent, whereas wind tunnel tests incline to overestimate wind speed reduction and sand-control efficiency. The study also finds that the aeolian sand accumulated around the fence can weaken the protection efficiency, and hence cleaning the aeolian sand accumulated around the fence should be done periodically to ensure the designed functions.

Determination of the efforts in two-way slabs of concrete through the finite difference method

From the implementation of analytical solutions for thin rectangular slabs using the Finite Difference Method, the present paper was developed with the purpose of comparing the determined efforts in a concrete plate with those that would be found using the tables originated from the plates theory of authors established in the literature. For this, the programming language Python was used, taking as a case study, a slab with dimensions of 5 meters long by 3 meters wide and thickness equal to 0.10 meters. In the analysis of the efforts, several support conditions were considered, in which the internal efforts and displacements obtained by the Finite Difference Method were compared with the results obtained through the tables proposed in literature. It was verified that the Finite Difference Method constitutes a good alternative for the resolution of thin solid plates, since the results were similar to the classic solution proposed in literature. The implemented program allows the visualization of the efforts through of spectrums of zone which facilitates the understanding of the distribution of the efforts along the slab, differing slightly from the uniform distribution adopted in the tables consulted.

Kuat Tekan Pelat Beton Menggunakan Pasir Wlingi dan Wiremesh Diameter 4 mm

Reinforced concrete is a combination of concrete and steel, where reinforcing steel provides tensile strength that concrete does not possess. Wlingi sand is sand that has a high level of silica. The function of silica to functional extender adds durability and anti-corrosion and anti-weathering properties. The purpose of this study is to find out the strong press, strong pull wire mesh, cracks, cracks, and faults and to find out if the test results can qualify as concrete plates—testing on test objects by the required SNI. The results showed that the compressive strength test value got an average value (28.38 Mpa), the wiremesh tensile strength test had average yield stress (393.42 Mpa), and tensile stress (569.30), and the seepage test were obtained the mean value (0.45%). The test for cracks and fractures obtained an average (1.72 Mpa) (2.18 Mpa). Test results showed wire mesh steel could be used as a concrete plate reinforcing because it has tensile voltage and melt voltage exceeding the minimum allowable limit of 390 Mpa and 240 Mpa.Beton bertulang adalah kombinasi antara beton dan baja, dimana baja tulangan memberikan kekuatan tarik yang tidak dimiliki beton. Pasir wlingi merupakan pasir yang memiliki kadar silika yang cukup tinggi, fungsi dari silika untuk ekstender fungsional menambah daya tahan dan sifat anti korosi serta anti pelapukan.Tujuan dari penelitian ini adalah untuk mengetahui kuat tekan, kuat tarik wiremesh, rembesan, retakan dan patahan dan untuk mengetahui apakah hasil pengujian dapat memenuhi syarat sebagai pelat beton. Pengujian pada benda uji sesuai dengan SNI yang disyaratkan. Pengujian dilakukan saat umur beton 28 hari dengan 3 benda uji berbentuk balok ukuran P×L×t=60×20×10(cm). Hasil penelitian menunjukkan bahwa pengujian kuat tekan didapat nilai rata-rata (28,38 Mpa), pengujian kuat tarik wiremeshmemiliki nilai rata-rata tegangan leleh (393,42 Mpa) serta tegangan tarik (569,30), pada pengujian rembesan didapat nilai rata-rata (0,45%), pengujian retakan dan patahan didapat rata-rata (1,72 Mpa)(2,18 Mpa). Hasil pengujian menunjukkan baja wiremesh dapat digunakan sebagai tulangan pelat beton karena memiliki tegangan tarik dan tegangan leleh melebihi batas minimum yang diijinkan yaitu 390 Mpa dan 240 Mpa.