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A research about study of sandstone slope stability using the Bishop Simplified method in Uu Samarinda has been conducted. This study was conducted to analyze the rebound number values of sandstone slopes, evaluate their stability level, and calculate the safety factor using the Bishop method. The results showed that the rebound number values were 22.34 at point 1, 19.83 at point 2, and 18.07 at point 3. The Uniaxial Compressive Strength (UCS) values at the observation points were 1.90 MPa, 1.62 MPa, and 2.21 MPa, respectively. Geological Strength Index (GSI) evaluation indicated a rating of 80–85, demonstrating intact/massive rock structure, fresh and unweathered rock surfaces, and very good rock quality. Based on the Bishop method analysis, the slope factor of safety in 6.525  with a probability of failure is 0.000%, indicating that the sandstone slope in Ulu Samarinda is highly stable even under external pressures such as heavy rainfall or minor earthquakes. This study provides crucial information on the mechanical characteristics and stability of sandstone slopes in ulu Samarinda, which can serve as a reference for technical planning, geotechnical risk mitigation, and the sustainable development of safe areas.

Expansive clay soil is soil that can expand and contract significantly in response to changes in soil moisture content. This study used an experimental method to stabilize expansive clay soil using a mixture of gypsum waste powder, which was tested using the Atterberg test, the Unconfined Compression Strength test, and the California Bearing Ratio test with mixture variations of 0%, 10%, 20%, and 30%. The results showed that the addition of gypsum waste powder could reduce the expansivity level of the soil from a very high level of 42% to a moderate level of 20%, increase the value in the Unconfined test at a maximum mixture of 10%, and increase the value in the CBR test at a maximum mixture of 30%. Based on the above description, this study aims to determine the extent of the effect of gypsum waste powder on expansive clay soil on the bearing capacity and compressive strength of expansive clay soil.

The use of sengon albasia ash waste as a partial cement substitute in concrete production is carried out to reduce combustion waste and also reduce cement use. This study focuses on the use of sengon albasia wood ash waste. The use of sengon albasia wood ash as a cement substitute causes a significant decrease in the slump test value. The use of sengon albasia wood ash as a partial cement substitute in concrete mixes actually produces different results depending on the proportion. If added as much as 10%, the concrete's compressive strength actually increases, but if it reaches 20% or 30%, the compressive strength actually decreases. This occurs because this type of wood ash has a significant water absorption capacity. As a result, the water that should be used for The chemical activity occurring between cement and water is diminished, so that the bond between the cement mixture as a binder and aggregate as a filler is reduced, and ultimately the concrete's compressive strength also decreases.

The soil in Kedungdandang Hamlet, Muncar, has previously been identified as expansive clay that is highly sensitive to changes in moisture content and exhibits significant shrink–swell behavior, which leads to a reduction in bearing capacity and structural damage such as cracking in floors and walls, therefore, soil improvement through stabilization is required. This study aims to determine the effect of adding cement and rice husk ash (RHA) on the mechanical properties of expansive clay soil by using 3% cement and 6%, 8%, and 10% rice husk ash based on the weight of the soil. The results of the unconfined compressive strength (UCT) test indicate that the natural soil has a qu value of 28.62 kN/m², which increases to 55.08 kN/m² with the addition of 3% cement and 6% RHA, to 62.66 kN/m² with 3% cement and 8% RHA, and reaches the highest value of 86.98 kN/m² for the mixture containing 3% cement and 10% RHA. This increase in qu value indicates that the stabilization process improves the mechanical properties of the soil through a pozzolanic reaction, resulting in a more stable soil structure and a higher bearing capacity.

Rock stability and service life in geotechnical and mining engineering are highly dependent on the rock's mechanical and physical parameters, where the variation in sandstone grain size is a crucial intrinsic factor. This study aims to comprehensively analyze the correlation between sandstone grain size with uniaxial compressive strength (UCS) and resistance to weathering (Slake Durability Index) in samples taken from the Balikpapan and Pulau Balang Formations in the Samarinda area, East Kalimantan. The research methodology involved a series of standard laboratory tests, including rock physical properties analysis, grain size distribution analysis, UCS testing, and slake durability testing through three cycles. The test results show a significant correlation: sandstone with finer grain sizes and higher density consistently demonstrates greater UCS values and a higher Durability Index, indicating superior mechanical and physical resistance. Specifically, the Pulau Balang Formation exhibits a more compact structure and finer grain size, resulting in better durability values compared to the Balikpapan Formation. These findings are important as a geomechanical data basis for slope design planning, rock mass stability analysis, and material selection in infrastructure projects or mining operations involving both formations.

Compressive strength is one of the mechanical properties of rock behavior. This study focuses on the Balikpapan and Kampungbaru Formations located in the Kutai Kartanegara area, East Kalimantan. The Schmidt Hammer testing method was applied due to the lack of previous studies utilizing this tool to evaluate rock hardness in correlation with compressive strength. The research site is situated in the Kutai Kartanegara area, specifically in the districts of Muara Badak, Muara Jawa, and Sanga-Sanga. Field observations revealed the presence of claystone slopes at predetermined locations. Based on the test results, the uniaxial compressive strength (UCS) values for the Balikpapan Formation range from 3.453 MPa to 5.454 MPa, while the Kampungbaru Formation ranges from 3.317 MPa to 8.571 MPa. The Schmidt Hammer rebound number (RN) values for the Balikpapan Formation range from 17 to 19.6, and for the Kampungbaru Formation from 15 to 23.7. A negative correlation was found between the rebound number and UCS, where higher RN values tend to correspond with lower UCS values. This is supported by the linear regression analysis showing a negative coefficient (-0.450).  

This research was conducted to analyze the performance of the extruder machine on the production quantity and quality of bricks. Analysis shows that the engine transmission uses a type B belt with a belt circumference of 1063.622 mm, so the v belt used by the motorbike has a nominal belt number of 41 inches. From the results of the linear regression of red bricks before being burned with a correlation value of 98.7%, it can be categorized as very strong. The linear regression for red bricks before burning is 0.10 while alpha < 0.05 so it can be concluded that there is no significant influence on variables X and Y. The linear regression for red bricks after burning is 0.07 while alpha < 0.05 so It can be concluded that there is no significant influence on variables X and Y.

This research utilizes waste from PLTU Tanjung Jati B Jepara, namely FABA (Fly ash Bottom Ash) as an alternative to fine and coarse aggregate. From this research, the physical properties of faba aggregate can be seen from the results of the faba aggregate sieve analysis test, which obtained a fineness modulus value of 1.74, which is included in the medium aggregate type. The water content of fine aggregate (fly ash) obtained a value of 3.63% and coarse aggregate (bottom ash) obtained a value of 1.5%. The fine aggregate sludge content (fly ash) obtained a value of 0%. The fine aggregate organic substance (fly ash) acquires a reddish brown NaOH color, therefore it must be washed before being used as a concrete mixture. The face dry specific gravity of fine aggregate (fly ash) obtained a value of 2.63 gr/cm2 and coarse aggregate 2.52 gr/cm2. From the data that has been obtained, faba aggregate is considered to have physical properties that meet the requirements for fine aggregate and can be used as a substitute for sand. The results of the final compressive strength of faba concrete and normal concrete at the age of 7 days and 28 days showed that the compressive strength of normal concrete (control) was higher than that of faba concrete. The standard deviation values ​​at the ages of 7 and 28 days are included in perfect working conditions because they have a standard deviation value of less than 3 MPa. From the results of the concrete flexural strength test, only the control concrete was 1;1.5 with a flexural strength of 4.18 MPa, which is close to SNI 2847:2013, namely with a minimum flexural strength of fs = 4.4 MPa. Normal concrete has a higher flexural strength than faba concrete. Based on tests carried out with the planned mix design, the 1:1.5 variation obtained the highest results.

This research is an experimental study on porous concrete and the use of fly ash as a binder for concrete to analyze the effect of compressive strength and porosity. The research method used in this study is the experimental method which is a research method used to find the effect of certain treatments on concrete. In this research, the concrete mix design uses a ratio of gravel and geopolymer paste as a binder, namely 4: 1 and uses a molarity ratio of 10M with differences in grading of coarse aggregate using sieves number 4, 1/2 ", and 3/8". The optimum compressive strength value was obtained in mix design 1 using sieve gradation no.4 which was 4.25 MPa at 28 days old. While the results of the highest porosity value were found in mix design 1 which was 7.15% at 28 days old

Mining with an open pit system is carried out by excavating and removing the overburden to obtain coal. However, before mining, it is important to obtain geotechnical data information. As well as the lithology of the rocks below the surface, it is necessary to carry out geotechnical drilling (full coring). This study can determine the value of slope geometry safety factors and plan safe slope geometry, both individual slopes and overall slopes. Therefore, this was done to determine the influence of GSI geotechnical parameters on the value of static and dynamic slope safety factors. The method used in determining the safety factor and the probability of an avalanche is the Morgenstern-Price boundary equilibrium method with the Generalized Hoek-Brown collapse criterion in static and dynamic slope conditions. The input parameters used in the analysis were natural density, compressive strength value (UCS), geological srength index (GSI), disturbance factor (D), intact rock constant (mi), as well as seismic load factor, and groundwater level. The optimal geometry on the Highwall slope is the configuration of the Highwall slope with a height of 74 m and an angle of 23°, supported by a single slope of 5-10 meters, a berm of 7 meters with an angle of 40°. Seam D Claystone lithology with GSI 50, Siltstone with GSI 70, Sandstone with GSI 70, and Seam E Claystone lithology with GSI 50, Siltstone with GSI 40, Sandstone with GSI 75.Can be applied within a safe limit where FK Static 1.7 PK Static 0% and FK Dynamic 1.4 PK Dynamic 6%.

This study examines the performance of a total of ten reinforced concrete T-beams, nine of which were made as hybrid beams by casting the web with LW concrete and the flange with HS concrete; the last beam was cast as a normal beam (entirely cast with HS concrete). All beams underwent testing under two-point loads following a 28-day period. The variables of the experimental program include the concrete grade within the web (46, 62, and 82 MPa) and stirrup distribution distances (100, 200, and 300 mm). The experimental program includes load-deflection curves and failure modes for hybrid and normal beams. The results showed that all the beams failed in shear-flexural mode. Also, increasing flange compressive strength increased shear. strength. Increasing stirrup distribution distance from 100 to 200 and 300 mm reduced the ultimate load capacity; specimens with stirrup spacing of 300 mm failed directly after yielding of steel due to crushing the concrete over the support and spalling concrete cover within the shear zone. The study also determined that reducing stirrup spacing to 100 mm did not alter the failure mode, as shear failure was dictated by the compressive strength of the lower layer of the hybrid beams (19 MPa compressive strength of LW concrete).

Concrete is an important aspect of building construction, one of which is road construction. Concrete is used for road construction because it has the advantages of high compressive strength, easy maintenance, ease of formation, and easy to obtain components. Road construction using concrete is applied to the reconstruction of the Kebumen South Ring Road, where the Kebumen South Ring Road is a 9.07 km long national road. National roads are arterial and collector roads in the primary road network system that connect provincial capitals, national strategic roads, and toll roads. Therefore, construction on national roads requires strong and good materials on the Kebumen South Ring Road to optimize road use. In this study, the concrete is composed of Bima cement as Portland cement, coarse aggregate from Kebumen, fine aggregate from the Progo River, and water from drilled wells. The admixture was obtained from a Conmix HK 2. Subsequently, all ingredients were mixed using a mixer truck. The concrete mixture was molded into cylinders and blocks. In this study, the average results of the 5-day concrete compressive strength test were obtainedwhich is 373.42 kg/cm2 and 28-day-old concrete is 442.32 kg/cm2. The average result of the 5-day concrete flexural test is50.65 kg/cm2 and that of 28-day-old concrete was 60.73 kg/cm2. The results are in accordance with the general specifications of the Bina Marga, namely, 45 kg.

The United Nations and the World Meteorological Organisation predict that around 5 billion people will lack clean water and even drinking water (Source: Conference on Our World in Concrete and Structure in Singapore). Based on the aforementioned phenomenon, given the abundant potential of seawater resources, there is an idea to use seawater as a concrete admixture, especially in building locations that often interact with seawater. Research is carried out in an effort to find alternatives to improve the mechanical properties of concrete such as compressive strength values, split tensile strength, namely by using additives as self-compacting concrete technology and making seawater and sea sand as a substitute for fresh water and river sand