The widespread use of chitosan waste shrimp extract to reduce the toxicity of certain heavy metals can reduce the escalation of the potential threat of environmental pollution. First) shrimp shell processing is intensively done so it is not wasted freely into the environment, second) toxicity of heavy metals decreased significantly with the application of chitosan adsorption method to heavy metals conducted in wider society. Bioadsorption method of heavy metals of ions Cadmium, Lead and Nickel using chitosan begins with insulation chitosan shell chitosan. The isolated chitosan was characterized. The performance of chitosan adsorption the three types of heavy metal tests was determined by chitosan interaction of each metal at varying pH interactions (pH 2-8). Interaction media conditions: 100 mL medium volume, total chitosan used 1 g, contact time 60 min, the heavy metal concentration of 200 μg/g cadmium ion test, Lead ions and Nickel respectively 100 μg/g. Determination of absorbance using Atomic Absorption Spectrophotometer. The measured value of the adsorbent is converted to the maximum chitosan adsorption concentration value. The adsorption capacity of metallic chitosan complex, maximum was achieved for metal Cd2+ at pH 2 of 198.2051 μg/g (99.05 %), metal Pb2+ at pH 4 of 59.3341 μg/g (59.33 %) and metals Ni2+ at pH 7 of 45.1334 μg/g (45.13 %). This result indicates that pH value of interaction media has an effect on chitosan adsorption to heavy metal test with Cd2+ ˃ ˃ Pb2+ ˃ Ni2+ sequence
This study aims to examine the effect of recycled Polyethylene Terephthalate (PET) artificial aggregate as a substitute for coarse aggregate on the compressive strength and flexural strength, and the volume weight of the concrete. PET plastic waste is recycled by heating to a boiling point of approximately 300°C. There are five variations of concrete mixtures, defined the percentage of PET artificial aggregate to the total coarse aggregate, by 0, 25, 50, 75 and 100%. Tests carried out on fresh concrete mixtures are slump, bleeding, and segregation tests. Compressive and flexural strength tests proceeded based on ASTM 39/C39M-99 and ASTM C293-79 standards at the age of 28 days. The results showed that the use of PET artificial aggregate could improve the workability of the concrete mixture. The effect of PET artificial aggregate as a substitute for coarse aggregate on the compressive and flexural strength of concrete is considered very significant. The higher the percentage of PET plastic artificial aggregate, the lower the compressive and flexural strength, and the volume weight, of the concrete. Substitution of 25, 50, 75 and 100% of PET artificial aggregate gave decreases in compressive strength of 30.06, 32.39, 41.73 and 44.06% of the compressive strength of the standard concrete (18.20 MPa), respectively. The reductions in flexural strength were by respectively 19.03, 54.50, 53.95 and 61.00% of the standard concrete's flexural strength (3.59 MPa). The reductions in volume weight of concrete were by respectively 8.45, 17.71, 25.07 and 34.60% of the weight of the standard concrete volume of 2335.4 kg/m3 Doi: 10.28991/cej-2020-03091626 Full Text: PDF
The number of problems found in the construction world include the difficulty or lack of fresh water in some areas to be mixed in the concrete, negligence in the maintenance of concrete and working process of concrete mainly on the concrete structures have a complex reinforcement and high concrete building structures. This study aims to find out the compressive strength, splitting tensile strength, absorption, and porosity of Self Compacting Concrete (SCC) using sea water as mixing water and with or without curing in sea water. The test specimens were made for each test specimen with the variation on age 1 day, 3 days, 7 days, 28 days and 90 days. The test method of compressive strength according to ASTM 39/C 39M-12a standard, tensile strength according to ASTM C496 / C496M-11 standard and the porosity and absorption according to ASTM C642-13 standard. The result of research was 1) the decrease in compressive strength in the specimen SCC-SWC was from 3 days, 7 days, 28 days and 90 days consecutive 13.20%, 12.90%, 12.80%, and 12.50%; 2) the decreases in splitting tensile strength in the specimen SCC-SWC were from the age of 3 days, 7 days, 28 days until the age of 90 days consecutive by 3.10%, 8.05%, 9.51%, and 9.21%; 3) the increase in the porosity values on the specimen SCC seawater without cured in sea water (SCC-SWC) at age 3 days, 7 days, 28 days and 90 days was 2.86%, 7.90%, 5.86%, and 5.55%, respectively; 4) the increase in the absorption values on the specimen SCC without curing at 3 days, 7 days, 28 days and 90 days was 15.80%, 20.57%, 15.84%, and 30.80%, respectively. The increase in mechanical properties (compressive strength and tensile strength) in the both of the specimen SCC-SC and SCC-SWC along with the decrease of porosity and absorption. Conversely, the decrease of compressive strength and tensile strength in the both of the specimen SCC-SC and SCC-SWC along with the increase in porosity and absorption value in the SCC.
Infrastructure development in Indonesia has increased. Therefore, the use of cement has increased as well. For this reason, it is necessary to replace the replacement cement material with environmentally friendly material. Fly ash is one of the waste materials that can be used as a substitute for cement. The purpose of this paper is to determine the compressive strength values of geopolymer mortars using fly ash-based from different Thermal Power Station and to determine the relationship of temperature curing with the compressive strength on geopolymer mortars using fly ash-based. The fly ash used was obtained from two Thermal Power Station in South Sulawesi, Indonesia. The sample is in the form of a cube with 5 cm × 5 cm size, with variations in room temperature; 65°C, 85°C, and 105°C. Activators used were Na2SiO3 and NaOH with 10 M with a ratio of Na2SiO3 per NaOH of 2. Compressive strength tests were carried out at 28 days. From the results of the study that the compressive strength of geopolymer mortar based on fly ash-Thermal Power Station A is higher than the compressive strength value of geopolymer mortar based on fly ash - Thermal Power Station B. The relationship of compressive strength with curing treatment with geopolymer mortar temperature variations is very significant. The higher the temperature, the higher the compressive strength of the mortar.
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