• Computers and Concrete
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• v.20 no.2
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• pp.155-164
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• 2017

During the past decades, development of reinforcing materials caused a revolution in the structure of high strength and high performance cement-based concrete. Among the most important and exciting reinforcing materials, Steel Fiber (SF) becomes a widely used in the recent years. The main reason for addition of SF is to enhance the toughness and tensile strength and limit development and propagation of cracks and deformation characteristics of the SF blended concrete. Basically this technique of strengthening the concrete structures considerably modifies the physical and mechanical properties of plain cement-based concrete which is brittle in nature with low flexural and tensile strength compared to its intrinsic compressive strength. This paper presents an overview of the work carried out on the use of SF as reinforcement in cement-based concrete matrix. Reported properties in this study are fresh properties, mechanical and durability of the blended concretes.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.11a
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• pp.55-56
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• 2011

This study is to investigate the engineering properties of low heat concrete incorporating improved ternary blended cement by combining OPC(original portland cement), blast furnace slag and fly ash. The results were summarized as following ; For ITB(Improved Ternary Blend)mixture was that setting time proved to be accelerated, and adiabatic temperature rises were low. The use of ITB resulted in an increase of initial compressive strength.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.33-39
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• 1999

This study was conducted to confirm the effect of bypass dust on the hydration and mechanical properties of the cement pastes and mortar obtained from ordinary Portland cement (OPC), OPC-slag and OPC-fly ash system. The rate of heat evolution is accelerated with the content of By-pass Dust(BD). total heat evolution increased because alkali-chlorides activated the hydration of blended cement. Compressive strength and bound water content show maximum value at 5wt% By-pass Dust(BD) on each curing time in ordinary Portland cement and slag blended cement. Ca(OH)2 content of Ordinary Portland Cement increased as the content of BD and curing time. In blended cement, the formation of Ca(OH)2 is active at early hydration stage. By pozzolanic reaction, the content of Ca(OH)2 is decreased as curing time goes by. According to the BD content stable chlorides complex of Friedel's salt (C3A·CaCl2·10H2O) is created. Due to the hydration activation effect of chlorides and alkali we observed Type II C-S-H, which developed into densest microstructure.

• KCI Concrete Journal
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• v.12 no.1
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• pp.47-56
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• 2000

Once a structure fabricated with mass concrete is in a form of wall such as retaining wall, side walls of a concrete caisson and so on, cracks induced by hydration heat have been known to be governed by exterior restraints which are mainly related to the boundary conditions of the structure. However, it is thought that the degree of restraints can be alleviated considerably only if a lift height of concrete placement or a panel size of the wall is selected properly before construction. As a way of minimizing thermal cracking commonly observed in massive wall-typed structure, this study aimed at evaluating effects of geometrical configuration on the temperature rise and thermal stress through parametric study. Evaluation of the effect was also performed for cement types using anti-sulphate cement, blast furnace slag cement and cement blended with two mineral admixture and one ordinary Portland Cement. so called ternary blended cement. As a result of analytical study, it was found that a lift height of concrete placement is the most important factor in controlling thermal cracking in massive wall, and the increase of a lift height is not always positive to the crack occurrence as not expected.

• Journal of the Korea Concrete Institute
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• v.20 no.4
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• pp.487-493
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• 2008

Tunnel structures are widely used for transportations in mountains areas. To shorten the construction period and to cut down the construction expenditure, a construction technique that a tunnel excavation process and a tunnel lining process are simultaneously performed is often applied in the field. However, due to the vibration and impact caused by excavation process, cracking and deterioration of tunnel lining concrete could happen. This research experimentally investigated the effective role of the usages of blended cement and recently developed nylon fibers for tunnel lining concrete. It has been observed that both nylon fibers and blended cement improve the durability and physical properties of concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.683-688
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• 2001

In case of constructing the concrete structures under seawater environment, the concrete suffers from deterioration due to penetration of various ions such as chloride, sulfate and magnesium in seawater. Tn the present study, Immersion tests with artificial seawater were carried out to investigate the resistance to seawater attack of antiwashout underwater concrete. From the results of compressive strength, it was found that blended cement concrete due to mineral admixtures such as fly ash(FA) and ground granulated blast-furnace slag(SGC), were superior to ordinary portland cement concrete with respect to the resistance to seawater attack. Moreover, XRD analysis indicated that the formed reactants of ordinary portland cement paste by sulfate and magnesium ions led to the deterioration of concrete. As expected, however, the blended cements with FA or SGC have a good resistance to seawater attack. This paper would discuss the mechanism of seawater deterioration and benefical effects of antiwashout underwater concretes with mineral admixtures.

• Resources Recycling
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• v.15 no.2 s.70
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• pp.24-31
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• 2006

The duality of recycled fine aggregate (RS) which was produced at the waste concrete crushing was investigated. The compressive strength, flexural strength and absorption of mortar utilized with RS were examined. It was evaluated on the application of RS as precast concrete aggregate. The density and absorption of RS were $2.31g/cm^3$ and 8.07% respectively, the quality of RS was satisfied with the criterion of KS F 2573 type 2. The maximum 28days compressive strength of mortar mixed with blended cement MRS1, MRS2 and MRS3 were developed with 15.8, 27.4 and 48.7MPa respectively, in condition to curing temperature $40^{\circ}C$ and water-cement ratio 37.5%. When blended cement MRS1 and MRS2 were used, the maximum flexural strength of mortar was developed at curing temperature $40^{\circ}C$ and water-cement ratio 35.0%. When blended cement MRS3 was used, the maximum flexural strength of mortar was developed at curing temperature $40^{\circ}C$ and water-cement ratio 37.5%. The absorption of mortar mixed with blended cement MRS1, MRS2 and MRS3 were indicated the range of $8.3{\sim}7.3%,\;6.5{\sim}8.5%$ and $3.5{\sim}6%$ respectively. Therefore, when the ratio of blended cement and RS is appropriately centre]led, it would be expected that MRS1, MRS2 and MRS3 will be able to apply the variable low strength, medium strength and high strength precaste concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.343-344
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• 2009

Compressive strength and chloride ions permeability measurements of ternary blended cement concretes incorporating ground granulated blast-furnace slag and fly ash were performed From a result of this study, it was found that there may be not a linear relationship between compressive strength and durability of ternary blended cement concretes.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.641-644
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• 2006

Considering properties of the low-heat concrete mixed with the blended cements, the influences compared blended cements with ordinary portland cement made experiments on. (1) Blended cements were superior to OPC in the fresh concrete flow that the use of blended cements reduced chemical admixture. (2) The more the use of additive increase, the more bleeding happens. So it is considered to heights, order, and rate of placement, curing methods and so on. (3) The use of blended cements increase long term strength after 28 days, but decrease early strength and durability. So it is considered to the curing methods and early frost damage, and endurance limit.

• International Journal of Concrete Structures and Materials
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• v.9 no.2
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• pp.241-254
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• 2015

A lot of reinforced concrete (RC) structures in Syria went out of service after a few years of construction. This was mainly due to reinforcement corrosion or chemical attack on concrete. The use of blended cements is growing rapidly in the construction industry due to economical, ecological and technical benefits. Syria is relatively rich in scoria. In the study, mortar/concrete specimens were produced with seven types of cement: one plain Portland cement (control) and six blended cements with replacement levels ranging from 10 to 35 %. Rapid chloride penetration test was carried in accordance with ASTM C 1202 after two curing times of 28 and 90 days. The effect on the resistance of concrete against damage caused by corrosion of the embedded steel has been investigated using an accelerated corrosion test by impressing a constant anodic potential. The variation of current with time and time to failure of RC specimens were determined at 28 and 90 days curing. In addition, effects of aggressive acidic environments on mortars were investigated through 100 days of exposure to 5 % $H_2SO_4$, 10 % HCl, 5 % $HNO_3$ and 10 % $CH_3COOH$ solutions. Evaluation of sulfate resistance of mortars was also performed by immersing in 5 % $Na_2SO_4$ solution for 52 weeks. Test results reveal that the resistance to chloride penetration of concrete improves substantially with the increase of replacement level, and the concretes containing scoria based-blended cements, especially CEM II/B-P, exhibited corrosion initiation periods several times longer than the control mix. Further, an increase in scoria addition improves the acid resistance of mortar, especially in the early days of exposure, whereas after a long period of continuous exposure all specimens show the same behavior against the acid attack. According to results of sulfate resistance, CEM II/B-P can be used instead of SRPC in sulfate-bearing environments.