Construction Technologies and Architecture Vol. 19

Abstract: Geopolymer concrete is an environmentally friendly alternative to cement as it can reduce carbon dioxide gas emissions during the production process. This study uses fly ash, a waste from the combustion of steam power plants, and perlite, a silicate glass rock with high alumina content, as cement replacement materials. Variations of perlite were used in geopolymer concrete mixtures to replace fly ash with percentages of 0%, 10%, 20%, and 30%, with a concentration of 12 M, and a Na₂SiO₃/NaOH ratio of 2.5 and AA/PM of 0.5. For the treatment of geopolymer concrete using oven curing method at 80°C for 16 hours. The results showed that variation 4 (fly ash 70% + perlite 30%) had an optimum compressive strength value of 27.145 MPa at the age of 28 days. The optimum split tensile strength value at the age of 28 days also occurred in variation 4 with a value of 3.130 MPa. In addition, variation 1 (100% fly ash + 0% perlite) had the highest slump value of 9.15 cm, while variation 4 (70% fly ash + 30% perlite) had the lowest density value of 2047.014 kg/m³.

Abstract: Concrete innovation in terms of changing some of its properties to improve quality and workability cannot be separated from the use of chemical additives, one of the admixtures that was used in this research was a type of superplasticizer with the brand Naptha Belide E121 Series. In this research the author wanted to examine the setting time admixture of Naptha Belide E121 Series in the application of 24-hour fast-track concrete K-500, the use of admixture doses in this research was 0%, 0.4%, 0.6% 0.8%, 1.0%, 1.2%, 1.4%, 1.6%, 1.8%, 2.0%, 2.2% of the weight of cement, while the cement used was OPC Cement (ordinary Portland cement) Type 1. This research aimed to determine the cement setting time in K-500 high-quality fast-track concrete applications with dose variations. The results of the setting time test of this research were that at a dose of 0%, the initial setting time was 117.01 minutes, while 0.4% - 1.0% of the initial setting time of cement increased or slowed down starting from 178.25 minutes - 240.71 minutes. At the same time, at doses of 1.0% to 1.8% doses, the initial setting time decreased or accelerated from 165.21 minutes to 92.86 minutes.

Abstract: Lignin is the largest component of biomass and the second most abundant natural polymer. Lignin-based products are commonly applied as binders, and are utilized for polymer applications. The purpose of this study is to use lignin as an admixture in mortar. The lignin dissolved in 1M NaOH solution, and the ratio was 1:5 by weight. The lignin contents utilised in this study were 1%, 2%, 3% by weight of cement and a cement water rasio of 0.4. Lignin as an admixture in mortar increased the flowability value. The flowability value increased as the lignin content rose. the highest compressive strength and flexural strength occured at 1% lignin content. They were 35.71 MPa and it was 5.49 MPa, at the age of 28 days. The longest setting time was obtained at 3% lignin content for initial setting time of 285 minutes, and final setting time of 540 minutes. Based on the results of the setting time test, it has been determined that the more lignin was mixed in, the longer the setting time will be. Therefore lignin as an admixture to the mortar makes changes its characteristics.

Abstract: Cement contributes CO₂ emissions to the atmosphere, which is harmful for human health. Several researchers have conducted experiments to find materials that have the potential to be used as cement substitutes. Fly ash and perlite are wastes that contain silica as well as high aluminum, so they have potential as cement replacement materials. In this study, geopolymer concrete mixtures were made using fly ash and perlite with a NaOH concentration of 10M – 16 M, a Na₂SiO₃/NaOH ratio of 2.5 and alkaline solution to fly ash ratio (AA/FA) of 0.5. The curing method used was using an oven at 80 °C for 16 hours. From the experimental results, the optimum compressive strength was 28.470 MPa with a 12M NaOH concentration. The optimum flexural strength was 2.387 MPa with a NaOH concentration of 12M.

Abstract: Hydrothermal carbonization (HTC) involves a thermochemical process at high temperature to reduce lignin and extractive in organic material using water as a medium. HTC produces a solid product known as hydrochar. Utilization of coconut coir in the concrete or mortar is an alternative to reducing agriculture waste. The application of natural fibers as aditif material in concrete and mortar effect the characteristics of cement mortar. The aim of this study is to investigate the impact of introducing coconut coir on mechanical properties of cement mortar at 28 days. This research used coconut coir, with a diameter of 0.420-0.149 mm. First, the coconut coir was boiled in a 5% potassium hydroxide (KOH) solution at 80°C for 30 minutes. Then followed the hydrothermal carbonization process for 1, 2, and 3 hours at 160°C. This research used a sand-to-cement ratio of 1:2.75 (by weight) and a water-to-cement ratio of 0.46. The hydrochar used in this study was 1% of cement (by weight). In the context of this research, physical and mechanical properties were observed such as flowability, compressive strength, flexural strength, and water absorption. The duration of the hydrothermal carbonization affected flowability, compressive strength and water absorption. It enhanced flowability, compressive strength, and water absorption. On the other hand, the hydrothermal carbonization duration increased as the flexural strength decreased.

Abstract: Steel construction is one of the main constructions for building and bridge structures because it has great tensile strength. However the main drawback is its resistance to corrosive environments which makes steel very corrosion prone. So that the use of steel construction must pay attention to the corrosion rate in the environment of use. So we try to do research on the level of corrosion rates in the tropics. This study aims to determine the atmospheric corrosion rate on steel plates in the city of Palu which is in the tropical region and the effect of the angle of installation of the steel plates. In this study there were 27 specimens and each variation of specimens totaled 9 consisting of PL45, PL90 and PL180 plates with a size of 160x80x5 mm. The results showed that the highest corrosion rate occurred in the first month and at an angle of 180⁰ with a corrosion rate value of 2.03 mpy and the lowest corrosion rate occurred in the third month and at an angle of 90⁰ with a corrosion rate value of 1.01 mpy. From this study it can be concluded that the corrosion rate that occurs in Palu City in the tropics is still in the very slow category for all test specimens based on corrosion engineering books.

Abstract: One type of hot mix asphalt that is commonly in flexible pavement types is the Asphalt Concrete - Wearing Course (AC-WC), this type of hot mix asphalt is a type of wear layer pavement which means this type of pavement is applied to the surface layer.It is regulated in the General Specifications of Bina Marga Year 2018 Revision 2. The method used is to take samples in the field, then measure the thickness of the sample. After that, laboratory tests were carried out, namely density to get density and marshal test to get quality. Then a comparison was made between the test results and the JMF plan. From the research results, it was found that there was a correlation between the thickness, density, and stability of the asphalt mixture. and the highest stability value was also obtained from the Marsal test results which were still below the specified standard.

Abstract: Using cement as the primary material for making concrete, around 7%-15%, requires a significant amount of energy and generates abundant waste, thus significantly impacting the environmental conditions. Innovative materials are needed as alternatives to cement. Fly ash, as an environmentally friendly material, can be a solution to minimize the use of cement. The selected fiber is Poly-Vinyl Alcohol (PVA) fiber due to its high tensile strength, which can effectively inhibit the rate of crack development occurring in the beams. The research process was divided into two stages: geopolymer mortar compressive strength testing and beams flexural testing. Compressive strength testing of geopolymer mortar was conducted on 50x50x50 mm cube samples, tested at ages of 3, 7, and 28 days using both air curing and moist curing methods. Geopolymer mortar was created using fly ash as the base material, along with activators such as Sodium Hydroxide (NaOH) and Sodium Silicate (Na₂SiO₃). Meanwhile, flexural beams were tested in 5 samples of 150x200 mm beams with a length of 3300 mm each. The samples consisted of a control beam, a beam reinforced with commercial grouting mortar, a beam reinforced with commercial grouting mortar and PVA geopolymer fibers, a beam reinforced with geopolymer mortar, and a beam reinforced with geopolymer mortar and PVA fibers. The research results indicated that adding PVA fibers to geopolymer mortar could enhance the maximum load-bearing capacity and stiffness of the beams. Regarding failure modes, beams reinforced with PVA-free geopolymer mortar experienced delamination failure, whereas beams reinforced with PVA-containing geopolymer mortar encountered debonding failure.

Abstract: This study aims to analyzes the shear behavior, crack patterns, and failure modes of reinforced concrete beams strengthened with geopolymer mortar panels (GMP) which consisted PVA fibers and wire mesh with varying bolts spacing. Shear behavior is discussed based on load-deflection behavior, maximum load, steel load strain, and concrete load strain. The research stages were divided into two, namely compressive strength of geopolymer mortar and shear test of reinforced concrete beams. The geopolymer mortar compressive strength test used 50x50x50 mm cube samples, tested at 3, 7, and 28 days. The geopolymer mortar was produced from fly ash as the base material and activators, such as sodium hydroxide and sodium silicate. Meanwhile, the beam shear test have cross section of 150x300 mm with a length of 2300 mm. There were four variation, namely CB, GM-W-200, GM-W-300, and GM-NW-200 beams. The results showed that adding reinforcement panels with geopolymer mortar material which consisted PVA fibers and wire mesh with distance of 200 mm (GM-W-200) affected the behavior of reinforced concrete beams to become more ductile and no longer occur shear collapse. Meanwhile, GM-W-300 and GM-NW-200 beams have not improved the bending behavior of the beams, and shear failure still occur as in CB beams.