• Advances in concrete construction
• /
• v.6 no.1
• /
• pp.29-45
• /
• 2018

This paper investigates the effect of inclusion of glass fibers on mechanical and fracture properties of binary blend geopolymer concrete produced by using fly ash and ground granulated blast furnace slag. To study the effect of glass fibers, the mix design parameters like binder content, alkaline solution/binder ratio, sodium hydroxide concentration and aggregate grading were kept constant. Four different volume fractions (0.1%, 0.2%, 0.3% and 0.4%) and two different lengths (6 mm, 13 mm) of glass fibers were considered in the present study. Three different notch-depth ratios (0.1, 0.2, and 0.3) were considered for determining the fracture properties. The test results indicated that the addition of glass fibers improved the flexural strength, split tensile strength, fracture energy, critical stress intensity factor and critical crack mouth opening displacement of geopolymer concrete. 13 mm fibers are found to be more effective than 6 mm fibers and the optimum dosage of glass fibers was found to be 0.3% (by volume of concrete). The study shows the enormous potential of glass fiber reinforced geopolymer concrete in structural applications.

• Advances in concrete construction
• /
• v.6 no.1
• /
• pp.87-102
• /
• 2018

Utilization of waste tires may be considered as one of the solution to the problems faced by the local authorities in disposing them. Reclaimed rubber (RR) is being used in concrete for replacing conventional aggregates. This research work is focused on the strength prediction of reclaimed rubber concrete using a Genetic Algorithm (GA) for M40 grade of concrete and comparing it with experimental results. 1000 sets were taken and 100 iterations were run during training of GA models. A base study has been carried out in this research work partially replacing cement with three types of fillers such as Plaster of Paris (POP), Fly Ash (FA) and Silica Fume (SF). A total of 243 cubes were cast and tested for compression using a Universal Testing Machine. It was found that SF produced maximum strength in concrete and was used in the main study with reclaimed rubber. Tests were conducted on 81 cube samples with a combination of optimum SF percent and various proportions of RR replacing coarse aggregates in concrete mix. Compressive strength tests of concrete at 7, 14 and 28 days reveal that the maximum strength is obtained at 12 percent replacement of cement and 9 percent replacement of coarse aggregates respectively. Moreover the GA results were found to be in line with the experimental results obtained.

• Computers and Concrete
• /
• v.20 no.1
• /
• pp.31-38
• /
• 2017

In the present study an Artificial Neural Network (ANN) was used to predict the compressive strength of self-compacting concrete. The data developed experimentally for self-compacting concrete and the data sets of a total of 99 concrete samples were used in this work. ANN's are considered as nonlinear statistical data modeling tools where complex relationships between inputs and outputs are modeled or patterns are found. In the present ANN model, eight input parameters are used to predict the compressive strength of self-compacting of concrete. These include varying amounts of cement, coarse aggregate, fine aggregate, fly ash, fiber, water, super plasticizer (SP), viscosity modifying admixture (VMA) while the single output parameter is the compressive strength of concrete. The importance of different input parameters for predicting the strengths at various ages using neural network was discussed in the study. There is a perfect correlation between the experimental and prediction of the compressive strength of SCC based on ANN with very low root mean square errors. Also, the efficiency of ANN model is better compared to the multivariable regression analysis (MRA). Hence it can be concluded that the ANN model has more potential compared to MRA model in developing an optimum mix proportion for predicting the compressive strength of concrete without much loss of material and time.

• Structural Engineering and Mechanics
• /
• v.67 no.3
• /
• pp.283-290
• /
• 2018

This paper presents the results of a study that investigated the influence of using recycled coarse aggregate (RCA) and recycled asphalt pavement (RAP) on the properties of pervious concrete (PC). The natural aggregate (NA) was replaced by RCA and RAP in the PC with replacement levels of 0%, 20%, 40%, 60% and 80% by the total weight of NA, respectively. In addition to incorporating RAP and RCA in the same mixes with replacement levels of: (1) 20% RAP and 80% RCA; (2) 60% RAP and 40% RCA; and (3) 80% RAP and 20% RCA. Water permeability, thermal conductivity, density, porosity, void content, and compressive, splitting tensile and flexural strengths were studied in this paper. The results showed that using RCA, RAP, and (RAP-RCA) enhanced the properties of PC in general and improved the mechanical properties significantly in particular. The optimum mix was reported to be the 60% RAP and 40% RCA. Accordingly, the RAP has the potential to be used in PC in order to reduce the negative impact of RAP on the human health and environment.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.7 no.1
• /
• pp.51-59
• /
• 2012

The cold weather concrete poured in the winter season can cause the problem of the Due to recent high-rise building is made. In this research, the nominal mix of the early strength in concrete tried to be set through the mixing proportion experiment for each empirical variable and each component strength properties for the early strength improvement tries to be examined. In the cold weather concrete experiment, the cement and high early strength (type3) cement improving in OPC than OPC was excellent. The polycarboxylic acid based compound was exposed to be excellent in the intensity revelation properties. Because the using of the fly ash was disadvantageous it was excluded from this experiment. It showed the optimum temperature for the intensity revelation up over $12^{\circ}C$.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.41 no.5
• /
• pp.104-105
• /
• 1999

This study was performend to examine Poisson's ration of polymer-modified asphalt concrete due to temperature variatino . Asphalt binder used in this study was an AC85-100, penetration grade of 85-100, and polymer for modifying asphalt were domestic LDPE(Low-density polyethylene) and SBS(Styrene-butadiene-styrene). Aggregate was a crushed gneiss which was most widely used in the middle part of Korea. Using these materias, asphalt mixture slab(340mm$\times$240mm$\times$80mm) with optimum asphalt content from mix design was made and cut into square pillar (80mm$\times$80mm$\times$160mm). Poisson's ration was measured in various temperture (-15$^{\circ}C$, -1$0^{\circ}C$, -5$^{\circ}C$,$0^{\circ}C$,5$^{\circ}C$,1$0^{\circ}C$ and 2$0^{\circ}C$) under the load of one axis repeated compression mode. Poisson's ration of normal asphalt polymer modified asphalt mixtures in normal temperatures. This indicated that AP mixture was more susceptible to temperature effects. From regression aalysis of experimental results, the difference of Poisson's ration between normal and low temperature showed that polymer modified asphalt mixture were lower than AP mixture except for SBS modified asplat mixture.

• Journal of the Korean institute of surface engineering
• /
• v.32 no.2
• /
• pp.165-171
• /
• 1999

The etching reaction of $UO_2$ in $CF_4/O_2$ gas plasma is examined as functions of $CF_4/O_2$ ratio, plasma power, and substrate temperature at up to $370^{\circ}C$ under the total pressure of 0.30 Torr. It is found that the highest etching rate is obtained at 20% $O_2$ mole fraction, regardless of r. f. power and substrate temperature. The existence of the optimum $CF_4/O_2$ ratio is confirmed by SEM, XPS and XRD analysis. The highest etching reaction rate at $370^{\circ}C$ under 150W exceeds 1000 monolayers/min., which is equivalent to 0.4$\mu\textrm{m}$/min. The mass spectrometry analysis results reveal that the major reaction product is uranium hexa-fluoride $UF_6$. Based on the experimental findings, dominant overall reaction of uranium dioxide in $CF_4/O_2$ plasma is determined : $8UO_2+12CF_4+3O_2=8UF_6+12CO_{2-x}$ where $CO_{2-x}$ represents the undetermined mix of $CO_2$ and CO.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.28 no.2
• /
• pp.126-130
• /
• 2015

In this study, some materials are organized and experimented with variables to obtain the optimum mix proportion for the mechanical property of halogen free flame resistance compound with varying addition of nano clay. Tensile strength, density and stiffness are tested in the room temperature. In this study, unlike existing layered structure, nano clay with tabular structure is used and sufficient stiffness, strength, thermal stability and gas block capability can be achieved with small amount of addition. Tensile strength and elongation test show high rupture strength only in specimens with compatibilizing agents while density test shows average measurement in all the specimens except T-9. It was confirmed that the measurement value according to the additives in compatibilizing agent or in nano clay of hardness test represents similarly.

• Advances in nano research
• /
• v.4 no.3
• /
• pp.181-195
• /
• 2016

Addition of nano-$SiO_2$ (NS) to geopolymer composites has been studied through measurement of compressive strengths, FTIR and XRD analysis. Alumino-silicate materials are coarse aggregate included waste concrete and demolished walls with its cementing binder, cement kiln dust (CKD) used and can possess a pronouncing activation for the geopolymer reaction resulting from the high alkali contents within. Materials prepared at water/binder ratios in a range of 0.30: 0.40 under curing of $40^{\circ}C$ and 100% Relative Humidity (R.H.), while the used activator is sodium hydroxide in the ratio of 2 wt. %. First, CKD is added in the ratio from 10 up to 50 wt., %, and the demolished walls was varied depending on the used CKD content, while using constant ratio of waste concrete (40 wt., %). Second step, depending on the optimum CKD ratio resulted from the first one (40 wt. %), so the control geopolymer mix composed of cement kiln dust, demolished walls and waste concrete in the ratio (40:20:40, wt %). Nano-silica partially replaced waste concrete by 1 up to 8%. Results indicated that, compressive strengths of geopolymer mixes incorporating nano-silica were obviously higher than those control one, especially at early ages and specially with 3%NS.

• Journal of the Korean Chemical Society
• /
• v.8 no.3
• /
• pp.98-102
• /
• 1964

As a practical method to produce the carbonaceous binder, the destructive distillation of coal tar has been studied. The optimum condition on binder in various temp. and cutting time were examined and the compositions of pitch were also examined in connection with ${\alpha},\;{\beta}\;and\;{\gamma}$ by solvent extraction. Coke powder was mixed with binder as treated pitch in the proportions of 77% of coke to 23% of pitch, to give a plastic mix which could then be pressed into molding. The properties of baked body after molding was tested. It was found that cutting of the coal tar at 350${\circ}C$, for 30 min., at 300${\circ}C$. for 1 hr., and at 250${\circ}C$. for 8 hrs. were good condition. Particularly, we found that the cutting of the coal tar obtained by destructive distillation at high temp. and in minimum period of time had shown the best condition for utilization of carbonaceous pitch as binder. The above mentioned cutting condition results in good quality of pitch which is available to be used as binder in carbon industry.