Relationship between againg and characteristic change of asphalt is not well known through asphalt rheolopy. Therefore, this study was conducted to evaluate characteristic change of asphalt cement due to againg based on experimental results of chromatogram and selected physical properties. Currently, three virgin asphalt cements were tested for physical properties and chromatograms before and after artificially conditioning for againg. Results in the current study showed that againg caused significant changes of physical properties and increase of larger size molecules and approximately corresponding reduction of smaller size molecule in asphalt cement molecular size distribution.

This study was performed to find out the effect about the spacing factor and durability factor to evaluate the durability of concrete in high-strength concrete with freezing and thawing as following each condition, 1) unit cement content : 500kg/$\textrm{m}^3$, 550kg/$\textrm{m}^3$ 2) water/cement ratio : 25%, 30%, 35% 3) air content : below 1.5%, 1.6~3.5%, 4~6%, over 7% From the results tested, a variation of air content was more effective to the durability of concrete than that of water/cement ratio and unit cement content.

Apparent diffusion coefficients of Cl-ions through hardened cement paste(HCP), which were partly substituted blending materials, were determined. Also, pore solution was extracted from HCP which were immersed in NaCl solution, and Cl- concentration of the solution were analyzed. Partly substitution of pozzolanic materials considerably reduced the diffusion rate for Cl-ions and Cl- concentration of pore solution. Binding capacity of Cl- is related to the content of Al2O3 and pozzolanic reactivity.

High-strength concrete were produced with super-plasticizer, silica fume, fly ash and blast furnace slag powder. Topics investigated inclued mix proportion, and effects of unit weight of binder, W/C ratio, additive type on the physical properties of high-strength concrete. As the result, at 20% of silica fume, unit weight of binder 700kg/$\textrm{m}^3$ and W/C=0.24, 28days compressive strength of concrete was over 1,000kgf/$\textrm{cm}^2$. And in cases of blending with silica fume 10% and fly ash or slag 10%, it was able to produce economical high-strength concrete with 28 days strength similar to silica fume 20% only, and higher strength after 90days.

For the purpose of improving the compressive strength of concrete, the high strength concrete which have the compressive strength about 800kg/$\textrm{cm}^2$ were made by using silica fume and high range water reducing admixture on reducing the water-cement ratio. But the facts that the slump loss of high strength concrete was high and the tensile strength and elastic modulus were not improved enough are indicated to problems which must be solved.

This study is designed for analyzing the properties of water-proofing on concrete according to the using EVA(ethylene vinyle acetate) emulsion, and the fine aggregate grading such as uniform, gap and continuously grading. And is aimed for presenting the reference data on the practical use.

To reinforce the foundation of building, the spun concrete pile is mostly used with consider the strength, economiability, durability, and etoetera. So, this study is designed for analyze the compressive strength of centryfugal manufacture concrete than that of normal concrete, and is aimed for presenting the reference data to the practical use of pile manufacture.

It is well-known that concretes under sea water environment show remarkably degrading phenomena physically by repeatable freeze-thawing action and chemically by penetration of soluted ions in sea water. In this study the influences of type of blending materials, their dosage and W/C ratio on freeze-thawing resistances of hardened cement concrete using foy ash, ground blast furnace slag, silica fume, EVA and SBR under sea-water environment were investigated.

Time dependent analysis of prestressed concrete beams subjected to pure torsion is studied. The present theory covers the behavior from the service load range to the ultimate stage. The tensile resistance of concrete is appropriately considered. The biaxial stress effects due to diagonal cracking are also taken into account. The time dependent aging, creep and shringkage effects are modelled by employing the equivalent nonmechanical torque concept. The present theory allows more accurate prediction of the service load behavior of pretressed concrete members.

This research has been carried out experimently to verify the structural efficiency of the reinforced concrete columns subjected to cyclic lateral loadings in the inelastic range. Sixteen specimens have been used in the tests, the factors such as reinforcing bars, shear-span ratio, axial load level and loading history being taken differently. The load-carrying capacities and the stiffness degradation in the inelastic range by cycle lateral load application have been counted by observing the load-deformation relationship, the crack initiation and propagation and the energy dissipation phenomena.

In staically indeterminate structures torsional stiffness is an important factor for prediction of mechanical behavior at all loading stages in reinfored concrete beams, which also for calculation of torsional moment. This paper proposes equation for postcracking torsional stiffness of reinforced concrete beams under pure torsion, which is derived considering the equilibrium and compatibility condition for shear panel based on the variable angle space truss model. The equation describes well the effect according to the variation of aspect ratio and steel volume ratio per unit concrete volume. It agress with experimental results in this paper as well as available literature.

The purpose of this paper is to suggest the equations that are able to predict the ultimate shear strength of the reinforced high-strength concrete beams. For this analysis, total of 83 rectangular beams were tested, and existing data of 400 was adopted. Through this analysis, the following equations are obtained. a) Shear Tensile Failure Equation : TVu={K1.K2(3.02 $\sqrt[3]{\Fc}$/$sqrt{\a/d\}$+1.74Pt)+(0.18a/d+0.567)Pww$\sigma$y]bd b) Shear Compressive Failure Equation : cVu={(29.85 $\sqrt[3]{\Fc}$-130)$\sqrt{d/a}$+(0.089$\sqrt{a/d}$=0.04)Pww$\sigma$y}bd

A numerical analysis in linear-elastic state for prestressed concrete tanks including the time-dependent effects due to creep and shrinkage of concrete, relaxation of prestressing cable have been studied by many researchers. In this paper, not only the time dependent factor but also the nonlinear elasto-plastic behavior are considered. Prestresses are considerde in vertical and circumferential direction.

Results of an experimental investigation of low-rise reinforced concrete shear walls with barbell cross section under cyclic loads are discussed and evaluated. Four halr scale models of test specimens with height to length ratio of 0.75 were experimented. The dimension of all walls is 1500mm wide $\times$ 950 mm high $\times$ 100 mm thick and the section of all boundary column at both ends is 200 mm $\times$ 200mm. Main variables are : design concept, vertical flexural reinflrcement ratios and reinforcement details(including crossed diagonal shear reinforcement in SW7 specimen). In SW7 specimen, maximum strength and consequently dissipating energy index were 1.45 and 1.28 times greater than those of SW6 specimen, respectively.

In order to investigate the behavior of newly developed PC deck plate bridges, 1/2 scale model specimen was tested under the 2 million cycles of fatigue loading. Forces between PC members were transfered by shear keys located at the faces of deck plate and girders. The test results showed that the test specimen maintained its original strength after 2 million cycles of fatigue loading.

This experimental study was performed to derive the relationship between the measured values(corrosion potential) and the actual amount of corrosion products(reinforcing steel weight loss rate). Also the growth of crack due to the steel corrosion was oberved. First, the reinforcing steel of R/C specimen was corroded with chloride penetration and accelerated galvanostatic corrosion method. And then, the corrosion potential of reinforcing steel was measured with nondestructive tester.

It was achieved to formulate numerically the stress-strain relationship of concrete, which is a fundamemtal factor for the Elasto-Plastic analysis of concrete structures, for normal concrete by using random statistics. As a result of experiment, in the shape of stress-strain curves of normal concrete it has approach linear from first loading to peak point, and after that point deformation increased radically and specimens were brokendown abruptly. From the multiple linear regression, and obtained the exponential equaion for stress-strain relationship of concrete as follows: $\sigma$/$\sigma$max=e(1-$\varepsilon$/$\varepsilon$max)$\varepsilon$/$\varepsilon$max

Polymer-Impregnated Concrete(PIC) can be considered composite material of concrete and polymer and has superior properties compared to conventional cement concrete, such as strength, stiffness, toughness, durability, water-proofing, chemical resistance. However, so far, the usage of PIC has been limited to repairing materials and non-structural applications, due to the lack of the design criteria and the analytical model to determine structural behavior. The objective of this study is to define the stress-strain response and strength characteristics of PIC in uniaxial and various biaxial compressive loading. On the bases of experimental results, general stress-strain relation, biaxial failure envelope and strength evaluation formular of PIC made with normal aggregate and methylmethacrylate(MMA) are proposed.

Result of an experimental study on the manufacture, the mechanical properties and waterightness of pitch-based carbon fiber reinforced fly ash.cement composites are presented in this paper. The carbon fiber reinforced fly ash.cement composites using early strength cement, silica powder and a small amount of stylene butadiene rubber latex are prepared with carbon fiber, foaming agents and mixing conditions. As a result, the mechanical and plysical properties such as compresive, tensile and flectural strengths, watertightness and cement composites are improved by using a small amount of stylene butadiene rubber latex.

The object of this study is to investigate material characteristics and flexural behavior of high strength concrete. Principal causes of variations of high compressive strength include the strength-producing capabilities of cement and silica hume. Compressive strength of 1200 kgf/$\textrm{cm}^2$ is introduced for identifying the effect of the variation of the size of porocity and alternative method of measurement, Acoustic Emition method, is applied to examine the phenominon of concrete failure. The main test variables in the beam element are tensile steel ratios, presence of shear reinforcement, and change of steel shape. The estimation of stress block in the flexural test of this element tends to support the present theory and may suggest a desirable shape of the stress block.

Fictitious Crack Model(FCM) is one of the Nonlinear Analysis Method which is presented strictly strain softening phenomena of concrete in the fracture zone. As no stress singularities occur, it is not necessary to use special crack tip elements for this analysis. A special feature of the used method is that it explains not only the growth of existing cracks, but aslo the formation of new crack, as it is assumed that cracks start forming when the tensile stress reaches ft, i.e., the same criterion is used for formation and propagation of cracks.

The concrete structures subjected to strong earthquakes may undergo hysteretic behavior and result in severe damage. The inelastic behavior and steffness degradation due to seismic loading must be properly modeled. The present study proposes a realistic model to assess the structural damage of concrete structures under seismic loadings. The present model also takes into account the probabilistic nature of seimic loading and thus the randomness of motion.

Wood, laminates, reinforced concrete, and some special types of metals systems with controlled grain orientation are often orthotropic and at least rectilinearly anisotropic from point to point, if regarded as homogeneous media. Orthotropic bodies where a crack is not associated with a plane of elastic symmetry may be conveniently treated as a crack problem in a generally anisotropic body. At this work, approach for the determination of the stress intensity factors (SIF) of anisotropic body using crack tip singular elements is presented. Caculated values are in good agreement with the others.

The effects of water-cement ratio, age, and admixture such as fly ash, silica fume on the bond strength between aggregate and mortar were investigated. As the result, with increasing of water-cement ratio, the bond strength was slightly decreased while the compressive strengths of mortar and concrete were seriously decreased. The rate of strength gain of bond strength was not decreased with increasing of water-cement ratio while that of compressive strength was gradually decreased.

The Seoul expressway is designed with prestressed concrete box girders. As a construction method, Precast Free Cantilever Method (P.F.C.M) is used which is introduced to Korea first time. Especially, the end spans in each bridge are designed to be constructed by cantilever method using temporary cantilever tendons. And pier and pierhead are prestressed vertically and horizontally.

Tests were conducted to get a mix proportioning of high strength concrete between σ28 and (C/W) using low quality materials easily purchased in situ. Superplasticizer was used as a chemical admixture to compensate low slump of base concrete keeping it up about 15±2㎝. General material properties such as modulus of elasticity, poisson's ratio, unit weight and stress-strain characteristic of high strength concrete were obtained. Test results show that mix proportioning of high strength concrete proposed in this paper have reasonable validity and these can be used as a design criteria in high strength concrete construction.

In recent years a reasonable supply and demand plan of construction materials which is based upon an accurate forecast has been greatly required to prevent construction works from delaying and slapdash. To meet an above requirement, a short-term forecasting system of construction materials, in this paper, is established, which is approached in engineering aspect and emerged from conventional forecasting systems. The major considerations in setting up this system are the distributed lag of consrection business indicators and seasonal variations in consumption of constuction materials.

Expert systems represent the application of artificial intelligence research that is at least 10-15 years old. It may well take another 5-10 years before the present technology is exploited by industry. The objective of this paper is to show the applicability of Combined Hypertext-Expert System Techniques to the professionals working in the construction industry. Expert systems alone don't give the user any control over the system. Hypertext systems that focus only on displaying messages have the opposite problem. While they allow the user to control the system., the only control the system designer has is in setting up the hypertext links. Therefore the combination of these two techniques, offered by KnowledgePro, may bring us closer to real user-expert communication. The system developed in this work offers information on ACI Manual concerning various problem areas in concrete practice, consultation about mix design of concrete and guidance to identify types of cracks in concrete. Once the type of crack is identified through the rule-based knowledge, the system provides the user with remedial measures through the control of the user.

By applying the newly developed techniques of polymer impregnated concrete (PIC) severely deteriorated and low quality concrete can be restored to an adequate structural material. Early deterioration of concrete causes severe problems for bridge deck concrete, pavement concrete for highways and airports, hydraulic structures and buiilding structures. Deterioration has its orgin in cracks on concrete surface, scaling of spalling due to freezing and thawing, neutralization of concrete, penetrations of water, salt, and calcium chloride. The objective of this study is to develope the new surface impregnants and strengthening techniques for them. It is found that the new impregnants and strengthening techniques developed in this study can retian the charecteristics of the existing concrete and decrease deterioration, and also increase durability, chemical resistance, strength, stiffness and ductility of the existing concrete.

To investigate the properties of High Strength Concrete with Fly-Ash for SAMSUNG San Bon high rised apartment, following variables has been strudied and constructed, successfully. Major variables are F/(F+C), W/C, S/A, Pumping Method, etc.. The results show that 15% of F/(F+C) is the best properties for compressive strength of concrete, temperature reduction and workability.

최근 도시지역에서의 교량가설시 P.C BOX GR. 교량이 차지하는 비율이 점차 증가하면서 도심교통난 유발을 최소화 할 수 있는 가설공법에 대한 필요성이 증대되고 있는 상황에서 Precast Element를 이용하여 P.C BOX GR.의 Cantilever 길이를 길게하여 MAIN BOX GR.의 폭을 감소시켜 광폭(B=20M이상)의 상부구조물 일지라도 하부구조를 일주식 교각으로 설치가능할 뿐만 아니라 MAIN BOX GR. 가설시 어떤 가설공법도 적용가능하므로 현장여건에 가장 적합한 가설공법을 용이하게 P.C BOX GR. 공법을 소개하고자 한다.