• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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• pp.755-758
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• 2004

Self-compactability is defined as a capability of concrete to be uniformly filled and compacted in every corners of formwork by its self-weight without vibration during placing. To evaluate the self compactability of self compacting concrete, the slump flow, the time of slump flow at 500mm and U-box apparatus testing methods are used. In this research, the fresh and hardened properties of self compacting concrete using ground granulated blast furnace slag as a part of cement were investigated for the volume contents of sand in the mortar. The workability, flowing characteristics, air content and compressive strength of concrete were tested and the results were compared with the different volume contents of sand in the mortar. In the experiment, we acquired satisfactory results at the point of flowing characteristics and strengths of self compacting concrete.

• Advances in concrete construction
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• 제15권4호
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• pp.251-267
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• 2023

In this paper, an experimental investigation is carried out to assess the inherent self-compacting properties of geopolymer mortar and its impact on flexural strength of thin-walled ferro-geopolymer box beam. The inherent self-compacting properties of the optimal mix of normal geopolymer mortar was studied and compared with self-compacting cement mortar. To assess the flexural strength of box beams, a total of 3 box beams of size 1500 mm × 200 mm × 150 mm consisting of one ferro-cement box beam having a wall thickness of 40 mm utilizing self-compacting cement mortar and two ferro-geopolymer box beams with geopolymer mortar by varying the wall thickness between 40 mm and 50 mm were moulded. The ferro-cement box beam was cured in water and ferro-geopolymer box beams were cured in heat chamber at 75℃ - 80℃ for 24 hours. After curing, the specimens are subjected to flexural testing by applying load at one-third points. The result shows that the ultimate load carrying capacity of ferro-geopolymer and ferro-cement box beams are almost equal. In addition, the stiffness of the ferro-geoploymer box beam is reduced by 18.50% when compared to ferro-cement box beam. Simultaneously, the ductility index and energy absorption capacity are increased by 88.24% and 30.15%, respectively. It is also observed that the load carrying capacity and stiffness of ferro-geopolymer box beams decreases when the wall thickness is increased. At the same time, the ductility and energy absorption capacity increased by 17.50% and 8.25%, respectively. Moreover, all of the examined beams displayed a shear failure pattern.

• Advances in concrete construction
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• 제6권3호
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• pp.285-296
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• 2018

In the present paper, the results of an experimental study of the bond between repair materials and mortar substrate subjected to hot climate is presented. Half-prisms of size $40{\times}40{\times}80mm$, serving as a substrate mortar samples (SUBM) were manufactured in the laboratory and then stored at an ambient temperature for 6 months. Five self compacting mortar mixes (SCMs) incorporating 0%, 10%, 20%, 30%, and 40% of natural pozzolana as white cement replacement were used as repair materials. Repaired composite samples (SCMs/SUBM) were cured at hot climate for different lengths of time (28 and 56-days). During the first week of curing, the composite samples were watered twice a day. The test carried out to assess the bond between SCMs and SUBM was based on three-point bending (3 PB) test. The obtained results have proved that it was feasible to produce compatible repair materals in this curing environment by using up to 30% natural pozzolana as white cement replacement.

• Computers and Concrete
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• 제19권2호
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• pp.121-126
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• 2017

This paper presents the effect of aggregate type on high temperature resistance of self-compacting mortars (SCM) produced with normal and lightweight aggregates like expanded perlite and pumice. Silica fume (SF) and fly ash (FA) were used as mineral additives. Totally 13 different mixtures were designed according to the aggregate rates. Mini slump flow, mini V-funnel and viscometer tests were carried out on the fresh mortar. On the other hand, bulk density, porosity, water absorption and high temperature tests were made on the hardened SCM. After being heated to temperatures of 300, 600 and $900^{\circ}C$, respectively, the tensile strength in bending and compressive strength of mortars determined. As a result of the experiments, the increase in the use of lightweight aggregate increased total water absorption and porosity of mortars. It is observed that, the increment in the usage of lightweight aggregate decreased tensile strength in bending and compressive strengths of mortar specimens exposed to high temperatures but the usage of up to 10% expanded perlite in mortar increased the compressive strength of specimens exposed to $300^{\circ}C$.

• Computers and Concrete
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• 제27권3호
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• pp.241-252
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• 2021

An experimental program was conducted to investigate the fresh properties, mechanical properties and durability characteristics of the self-compacting mortars (SCM) produced with pumice powder and Artificial Lightweight Fine Aggregate (aLWFA). aLWFA was produced by using fly ash. A total of 16 different mixtures were designed with a constant water-binder ratio of 0.37, in which natural sands were partially replaced with aLWFA and pumice powder at different volume fractions of 5%, 10% and 15%. The artificial lightweight aggregates used in this study were manufactured through cold bonding pelletisation of 90% of class-F fly ash and 10% of Portland cement in a tilted pan with an ambient temperature and moisture content. Flowability tests were conducted on the fresh mortar mixtures beforehand, to determine the self-compacting characteristics on the basis of EFNARC. To determine the conformity of the fresh mortar characteristics with the standards, mini-slump and mini-V-funnel tests were carried out. Hardened state tests were conducted after 7, 28 and 56 days to determine the flexural strength and axial compressive strength respectively. Durability, sorptivity, permeability and density tests were conducted at the end of 28 days of curing time. The test results showed that the pumice powder replacement improved both the fresh state and the hardened state characteristics of the mortar and the optimum mixture ratio was determined as 15%, considering other studies in the literature. In the aLWFA mixtures used, the mechanical and durability characteristics of the modified compositions were very close to the control mixture. It is concluded in this study that mixtures with pumice powder replacement eliminated the negative effects of the aLWFA in the mortars and made a positive contribution.

• Computers and Concrete
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• 제21권2호
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• pp.111-116
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• 2018

Establishment of test methods to assess the fresh properties of self-compacting concrete (SCC) are required to ensure the homogeneity in fresh and hardened states. This paper discusses the suitability of a simple test method for assessing the slump flow and stability of SCC by testing on self-compacting mortar (SCM) fraction. The proposed test method aims at investigating slump flow diameter test and sieve stability test of SCC by testing SCM fraction with a plunger penetration apparatus. A central composite modeling design was performed to evaluate the effects of water/cement ratio (W/C), superplasticizer dosage (SP) and powder marble content (MP) on slump flow diameter, stability and plunger penetration test of fresh SCC. The responses of the derived statistical models are slump flow (Sf), sieve stability (S) and plunger penetration (P). Relationships obtained in this study show acceptable correlations between plunger penetration test value and slump flow diameter test results and stability. It should note that the developed relationships are very useful to predict slump flow diameter and stability of studied SCC mixtures by carrying out a simple plunger penetration test on its mortar, which can save labour and time in laboratory experiments.

• 콘크리트학회논문집
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• 제11권6호
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• pp.69-78
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• 1999

Hydroxyethyl cellulose -based-viscosity modifying admixture and melamine-basd-superplasticizer were selected to be admixtures for self-compacting concrete based on the test results of fluidity and air content of mortar using 3 different viscosity modifying admixtures. The experimental results show that the initial and final set of self-compacting concrete and fly ash concrete with viscosity modifying admixture only have been delayed approximately 5 hours and 8~9 hours, respectively. It is found that the optimum dosage of viscosity modifying admixtures, coarse aggregate and cement content are 0.2% of water content, under 742 kg/$\textrm{m}^3$ and over 364 kg/$\textrm{m}^3$, respectively. Test results also show that the optimum fly ash in replacement of cement is 10% of cement weight for the enhancement of fluidity and long-term strength.

• 콘크리트학회논문집
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• 제17권3호
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• pp.473-480
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• 2005

In this study, a mix design for self compacting concrete was based on Okamura's method and concrete incorporated just a ground granulated blast furnace slag. Replacement ratio of slag is in the range of $20-80\%$ of cement matrix by volume. For the optimal self compactability in mixture incorporating ground granulated blast furnace slag, the paste and mortar tests were first completed. Then the slump flow, elapsed time of 500mm slump flow, V funnel time and filling height by U type box were conducted in concrete. The volume of coarse aggregate in self compacting concrete was in the range of $50-60\%$ to the solid volume percentage of coarse aggregate. Finally, the compressive and splitting tensile strengths were determined in the hardened self compacting concrete incorporating ground granulated blast furnace slag. From the test results, it is desirable for self compacting concrete that the replacement of ground granulated blast furnace slag is in the range of $40-60\%$ of cement matrix by volume and the volume of coarse aggregate to the solid volume percentage of coarse aggregate with a limit of $55\%$.

• Computers and Concrete
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• 제20권3호
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• pp.283-290
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• 2017

The aim of this study is to investigate the effect of the bond strength of self-compacting mortars (SCMS) produced from ground pumice powder (GPP) as a mineral additive. In this scope, six series of mortars including control mix were prepared that consist of 7%, 12%, 17%, 22% and 27% of ground pumice powder by weight of cement. A total of 54 specimens of $40{\times}40{\times}160mm$ were produced and cured at the age of 3, 28 and 90-day for compressive and tensile strength tests and 18 specimens of $150{\times}150{\times}150mm$ mortar were prepared and cured at 28 days for bond strength tests. Flexural tensile strength and compressive strength of $40{\times}40{\times}160mm$ specimens were measured at the curing age of 7, 28 and 90-day. Mini V-funnel flow time and mini slump flow diameter tests were also conducted to obtain rheological properties. As a result of the study, it was observed that the SCMs containing 12% of GPP has the highest bond strength as compared to control and GPP mortars. Compressive strength slightly increased up to 12% of GPP.

• Computers and Concrete
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• 제18권6호
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• pp.1065-1082
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• 2016

The main aim of this study is to predict the compressive and flexural strengths of self-compacting mortar (SCM) containing $nano-SiO_2$, $nano-Fe_2O_3$ and nano-CuO using wavelet-based weighted least squares-support vector machines (WLS-SVM) approach which is called WWLS-SVM. The WWLS-SVM regression model is a relatively new metamodel has been successfully introduced as an excellent machine learning algorithm to engineering problems and has yielded encouraging results. In order to achieve the aim of this study, first, the WLS-SVM and WWLS-SVM models are developed based on a database. In the database, nine variables which consist of cement, sand, NS, NF, NC, superplasticizer dosage, slump flow diameter and V-funnel flow time are considered as the input parameters of the models. The compressive and flexural strengths of SCM are also chosen as the output parameters of the models. Finally, a statistical analysis is performed to demonstrate the generality performance of the models for predicting the compressive and flexural strengths. The numerical results show that both of these metamodels have good performance in the desirable accuracy and applicability. Furthermore, by adopting these predicting metamodels, the considerable cost and time-consuming laboratory tests can be eliminated.