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High strength concrete is currently a very important part in construction, namely construction that has very high strength. The strength of concrete depends on the material used and its size. The size of the concrete constituent materials affects the porosity of the resulting concrete because porosity affects the strength of the concrete. For this reason, efforts are made to use concrete constituent materials that can reduce porosity in concrete. Various materials can be used as additives to give concrete high strength. Among these materials are fly ash and silica fume. Fly ash is a product of coal combustion and functions as a substitute for pozzolanic materials in cement as much as 0, 5, 7.5, 10, 12.5, 15, and 17.5% because it has a very fine grain size < 350 mesh and silica fume ash, which functions as a substitute for fine aggregate 0, 10, 15, 20, 25, 30, and 35% which comes from the ashes of burning refined palm shells with a size < 350 mesh. Materials were prepared, namely: cement, fine aggregate, coarse aggregate, fly ash, silica fume, and weighing water. All the ingredients were stirred until homogeneous and put into a cube-shaped mold measuring 150 x 150 x 150 mm while compaction was carried out using an iron stick, then the mold was left for 24 hours, removed from the mold then soaked in water and soaked in water for 28 days. The compressive strength test and characterization of XRF and XRD and SEM were carried out. Based on the research as outlined in the graph, the maximum compressive strength of substitution of 12.5% fly ash into cement is 45.20 MPa, while the substitution of silica smoke from boiler slag into fine aggregate has a maximum compressive strength of 25% of 50.84 MPa. The results of the XRF characterization of high strength concrete showed that the dominant compounds were 54.60% CaO, and 32.50% SiO2, followed by other compounds. The results of the XRD test showed that the phases formed were calcite (Ca), quartz (SiO2), and anorthite (CaAl2Si2O8) and the distribution of C-S-H was fairly even in the concrete. Thus, fly ash and burning ash of palm shells can affect the compressive strength of concrete for the better, namely the strength increases higher than normal concrete. [ABSTRACT FROM AUTHOR]

This research paper is about the Utilization of Silica Fume with Fly Ash and Properties of Portland Cement-Silica Fume-Fly Ash-Concrete. Concrete is a man or a machine-made construction material that has more usage in the construction field, It is necessary to make construction secure and safe for making high strength concrete the admixture Silica fume is the best choice to make the compressive strength of concrete very high but for having a high Compressive strength concrete it has to check the porosity and strength of concrete in this research the compressive strength and porosity of concrete is checked and resulted. In this research, the content of the admixtures is Silica fume 7.5%, 14.5%, and Fly ash 17%, 35% on the property of grade 43 Portland cement. Silica Fume is a very expensive material in the construction industry so we have to use some more materials to make the Portland cement content less, the admixture Fly ash is the best material for the other admixture. Silica Fume helps to prepare high compressive strength concrete and Fly ash helps to make the porosity low. The percentages of Silica fume and Fly ash which is use, was not used before and the reason for that is to make concrete more strengthen and lighter. [ABSTRACT FROM AUTHOR]

During the casting in a warmer tropical temperature, a setting time delay is required to maintain the workability of the concrete, commonly achieved by the addition of admixtures i.e. silica fume (SF), fly ash (FA), and Plastrocrete®. However, high sugar content Coca-Cola in niche conditions is proposed as an ingredient for delaying concrete setting time in combination with conventional admixtures. This research aims to compare the setting time of admixtures from CocaCola and Plastocrete® RT6 plus in concrete mixing with control data of concrete mixed with SF or FA. The second aim is to measure the compression strengths between combinations of Coca-Cola and Plastocrete® RT6 plus. Concretes were produced with admixtures of SF, FA, Plastocrete® RT6plus, or Coca-Cola. The concrete used to control was f'c20 and f'c25, while other concrete mixes were produced with the addition of Coca-Cola at 0.15% from the weight of cement at variation of moisture treatments. The first method to produce concrete (f'c20+Plas0.23%+Cola0.15% and f'c25+Plas0.23%+Cola0.15%) did not employ water reduction. The second concrete productions (f'c25+Plas0.46%+Cola0.15% and f'c25+Plas0.46%+Cola0.15%) reduced the addition of water at 8.8% (v/w). The first concrete production method had a setting time 44% longer than control. The reduced water concrete in the second productions had a setting time 34% longer than control. Meanwhile, the Plastocrete® RT6 Plus admixture with the reduced water delayed the concrete setting time by 26% longer than control. The delayed setting time of Plastocrete® RT6 Plus admixture with reduction of water was shorter than in the treatment with Coca-Cola. The combination of the addition of Coca-Cola with Plastocrete® RT6 plus by reducing the amount of adding Coca-Cola to 0.10% with Plastocrete® RT6 plus can delay concrete setting time by 51% longer than normal concrete and increase concrete compressive strength by 13% higher than normal concrete. Mixing Coca-Cola with Plastocrete® RT6 plus not only provided an optimal delay effect on setting time but also significantly increase the compressive strength that was desired during the casting in warm tropical weather applied in building construction of Mulawarman University, Samarinda, Indonesia. [ABSTRACT FROM AUTHOR]