The Effect of Sand Type on the Rheological Properties of Self-Compacting Mortar

In order to understand the effect of sand type on the rheological properties of self-compacting mortar, four varieties of sand, namely, quartz sand (QS), river sand (RS), and two kinds of manufactured sand, marked as MS-A and MS-B, were studied. As part of this study, the sands’ particle shape parameters, such as their length:width ratio and roundness, were determined. Mortars containing the four varieties of sand were tested using the slump flow test and the V-funnel test in oven-dried (OD) and saturated surface-dried (SSD) conditions in order to identify the water absorption, shape-related differences, and specific gravity in their rheological performance. The changing trends of the slump flows and the V-funnel times of the different mortars in OD and SSD were similar. By eliminating the influence of water absorption on mortar rheology, shape–weight parameters, such as the ratio between the length:width ratio and specific gravity (LWS) and the product of roundness and specific gravity (ROS), were defined in order to quantify the compound effects of sand type on mortar rheology. The regression analysis showed an excellent linear correlation between slump flow and both LWS and ROS, and a very good linear correlation was also demonstrated between the V-funnel time and both LWS and ROS. Based on the particle shape–weight parameters, the rheological properties of mortars can be predicted. Based on the mortar rheological threshold theory, the self-compacting mortar (SCM) zone can be drawn. The predicted SCM zone overlaps considerably with the experimental SCM zone for MS-A.

Tensile strength of sands treated with microbially induced carbonate precipitation

During large earthquake events where bending moments within soil cements are induced, the tensile strength of cemented soil may govern the deformational behavior of improved ground. Several studies have been conducted to assess the tensile strength of artificially cemented sands that use Portland cement or gypsum; however, the tensile strength of microbially induced carbonate precipitation (MICP)-treated sands with various particle sizes measured through direct tension tests has not been evaluated. MICP is a biomediated improvement technique that binds soil particles through carbonate precipitation. In this study, the tensile strength of nine specimens were measured by conducting direct tension tests. Three types of sand (coarse, medium, and fine) were cemented to reach a heavy level of cementation (e.g., shear wave velocity of ∼900 m/s or higher). The results show that the tensile strength varies between 210 and 710 kPa depending on sand type and mass of carbonate. Unconfined compressive strength (UCS) tests were performed for each sand type to assess the ratio between tensile strength and UCS in MICP-treated sands. Scanning electron microscopy (SEM) images and surface energy measurements were used to determine the predominant failure mode at particle contacts under tensile loading condition.

Keanekaragaman Tumbuhan Potensi Obat Tradisional di Hutan Kerangas Pasir Putih KHDTK UM Palangkaraya

Keanekaragaman hayati di Indonesia sangat berlimpah terutama tanaman yang memiliki khasiat sebagai obat tradisional. Masyarakat Indonesia memanfaatkan tanaman obat tradisional sebagai bahan untuk pengobatan berbagai macam penyakit. Biaya pengobatan yang mahal membuat masyarakat beralih ke pengobatan secara tradisional. Potensi hasil hutan tidak hanya berupa kayu, tetapi juga bermanfaat lain seperti tumbuhan hutan berkhasiat obat untuk kesehatan. Hutan Kalimantan memiliki berbacam-macam tipe habitat, salah satunya adalah hutan kerangas pasir putih. KHDTK UM Palangkaraya merupakan suatu kawasan hutan pendidikan dengan luas 4.910 ha yang mempunyai 5 tipe habitat yang salah satunya adalah hutan kerangas pasir putih. Penelitian ini bertujuan untuk mengetahui keanekaragaman tumbuhan obat di kawasan hutan kerangas pasir putih. Metode yang digunakan adalah metode sensus dengan plot bertingkat ukuran 30 m x 30 m sebanyak 5 plot dan juga wawancara dengan masyarakat lokal. Hasil penelitian diperoleh terdapat 30 jenis tumbuhan berpotensi sebagai obat tradisional yang tumbuh menyebar di kawasan hutan kerangas pasir putih dengan keberadaan jenis tumbuhan obat tersebut ditentukan oleh topografi, jenis tanah dan kerapatan tegakan. Persentase keberadaan tumbuhan obat di plot yang diamati adalah 28,61% dari populasi jenis penyusun hutan kerangas pasir putih. Biodiversity in Indonesia is very abundant, especially plants that have properties as traditional medicine. Indonesian people use traditional medicinal plants as ingredients for the treatment of various diseases. Expensive medical expenses make people switch to traditional treatment. The potential of forest products is not only in the form of wood, but also other benefits such as forest plants which have medicinal properties for health. Kalimantan forests have many varieties of habitat types, one of which is white-sand type of heath forest. KHDTK UM Palangkaraya is an educational forest area with an area of ​​4,910 ha which has 5 habitat types, one of them is white-sand type of heath forest. This study aims to determine the diversity of medicinal plants in the area of ​​white-sand kerangas forest. The method research with census syatem in 30m x 30m multilevel plots and 5 interviews with local communities. The results showed that there were 30 species of plants that have the potential as traditional medicines that grow spreading in the area of white sand type of heath forest as with the presence of these types of medicinal plants determined by topography, soil type and stand density. The percentage of the presence of medicinal plants in the observed plot was 28.61% of the population the type of white-sand type of heath forest as compiler.