Yang-Seob Soh

Performance of polymer-modified self-leveling mortars with high polymer–cement ratio for floor finishing

Abstract Recently, polymer-modified mortar has been studied for proposed use on industrial floors as top coat with thin thickness, typically 5–15 mm. The purpose of this study is to evaluate basic properties of self-leveling materials using polymer dispersions as kinds of SBR latex, PAE and St/BA emulsions for thin coatings (under 3 mm in thickness). Superplasticizer and thickener have been included in the mixes to reduce bleeding and drying shrinkage as well as to facilitate the workability required. The self-leveling materials using four types of polymer dispersion are prepared with polymer–cement ratios of 50% and 75%, and were tested for basic characteristics such as density, flow, consistency change and adhesion in tension. The test results showed that the self-leveling mortars using PAE emulsion at a curing age of 28 days were almost equal to those of conventional floor using urethane and epoxy resins. The adhesion in tension of self-leveling mortars using SBR latex and PAE emulsion at a curing age of 3 days is over 1.67 MPa. It was noted that the consistency change is strongly dependent on the type of polymer dispersion. It is concluded that the self-leveling mortars with polymer dispersions can be used in the same manner as conventional floor-finishing materials using thermosetting resin in practical applications.

Effects of emulsifiers on properties of poly(styrene-butyl acrylate) latex-modified mortars

Abstract Two styrene–butyl acrylate copolymer latices having the same chemical components but different emulsifiers were synthesized under the same reaction conditions, and their effects on such properties as workability, air content, compressive strength, flexural strength and water absorption of fresh and hardened polymer-modified mortars were assessed and discussed. From the tested properties of the polymer-modified mortars, it is concluded that a polymeric emulsifier provides a much more positive effect on the properties of the polymer-modified mortars than a low-molecular emulsifier.

Comparison of Deterministic Calculation and Fuzzy Arithmetic for Two Prediction Model Equations of Corrosion Initiation

abstract The existing deterministic solution for prediction model of corrosion initiation cannot reflect input variable uncertainties very well. Thus there is a growing tendency for a stochastic model based on the probabilistic method to be developed and applied. This paper presents an approach to the fuzzy arithmetic based modeling of the chloride-induced corrosion of reinforcement in concrete structures that takes into account the uncertainties in the physical models of chloride penetration into concrete and corrosion of steel reinforcement, as well as the uncertainties in the governing parameters, including concrete diffusivity, concrete cover depth, surface chloride concentration and critical chloride level for corrosion initiation. There are a lot of models for predicting the onset time of reinforcement corrosion of structures exposed to corrosion environment. In this work, the RILEM model formula and Cranks solution of Ficks second law of diffusion are used. The parameters of the models are regarded as fuzzy numbers with proper membership function adapted to statistical data of the governing parameters, while the fuzziness of the corrosion time is determined by the fuzzy arithmetic of the interval arithmetic and extension principle. An analysis is implemented by comparing the deterministic calculation with fuzzy arithmetic for the above two prediction models.

Hydration Reaction of Non-Sintering Cement Using Inorganic Industrial Waste as Activator

Greenhouse gas reduction will be highlighted as the most pending question in the cement industry in future because the production of Portland cement not only consumes limestone, clay, coal, and electricity, but also release waste gases such as , and NOX, which can contribute to the greenhouse effect and acid rain. To meet the increase of cement demand and simultaneously comply with the Kyoto Protocol, cement that gives less discharge should be urgently developed. This study aims to manufacture non-sintering cement(NSC) by adding phosphogypsum(PG) and waste lime(WL) to granulated blast furnace slag(GBFS) as sulfate and alkali activators. This study also Investigates the hydration reaction of NSC through analysis of scanning electron microscopy(SEM), X-ray diffraction(XRD), differential thermal analysis(DTA), and pH. Results obtained from analysis of the hydrate have shown that the glassy films of GBFS are destroyed by the activation of alkali and sulfate, ions eluted from the inside of GBFS react with PG and produce ettringite, and consequently the remaining component in GBFS slowly produced C-5-H(I) gel. Here, PG is considered not only to play the role of simple activator, but also to work as a binder reacting with GBFS.

Durability of Polymer-Modified Mortars Using Acrylic Latexes with Methyl Methacrylate

Polymer-modified mortar and concrete are prepared by mixing either a polymer or monomer in a dispersed, or liquid form with fresh cement mortar and concrete mixtures, and subsequently curing, and if necessary, the monomer contained in the mortar or concrete is polymerized in situ. Although polymers and monomers in any form such as latexes, water-soluble polymers, liquid resins, and monomers are used in cement composites such as mortar and concrete, it is very important that both cement hydration and polymer phase formation proceed well the yield a monolithic matrix phase with a network structure in which the hydrated cement phase and polymer phase interpenetrate. In the polymer-modified mortar and concrete structures, aggregates are bound by such a co-matrix phase, resulting in the superior properties of polymer-modified mortar and concrete compared to conventional mortar and concrete. The purpose of this study is to obtain the necessary basic data to develope appropriate latexes as cement modifiers, and to clarify the effects of the monomer ratios and amount of emulsifier on the properties of the polymer-modified mortars using methyl methacrylate-butyl acrylate(MMA/BA) and methyl methacrylate-ethyl acrylate(MMA/EA) latexes. The results of this study are as follows, the water absorption, chloride ion penetration depth and carbonation depth of MMA/BA-modified mortar are lowest. However, they are greatly affected by the polymer-cement ratio rather than the bound MMA content and type of polymer.

Nominal Cover Thickness Design of RC Quantitatively Considering Environment Condition by Means of Fuzzy Inference System

Abstract This article involves designing the Nominal cover thickness by means of fuzzy inference system(FIS) for quantitatively representing the environment load coefficient to reinforced concrete in corrosive environment. In this work, several variables defining the quality of concrete and environment condition, viz. environment load coefficient(ELC), were treated as fuzzy variables. To qualify ELC the environment conditions of cycle degree of wet-dry, relative humidity, distance from coast and temperature were used as input variables. To determine the Nominal cover thickness a qualified ELC, concrete grade, and water-cement ratio were used. The membership functions of each fuzzy variable were generated from the engineering knowledge based on some references as well as some international codes of practice.The restraining conditions of this work are as follows;1. The knowledge bases for generating the rule base of fuzzy inference system are derived just from some references as well as BS 8110 and BS EN 206-1/BS 8500.2. The procedure of this study is applicable only to the corrosive environments.3. It is limited to the cover to reinforcement for normal building structures with an intended service life of at least 50 years.

Fuzzy Inference Based Design for Durability of Reinforced Concrete Structure in Chloride-Induced Corrosion Environment

This article involves architecting prototype-fuzzy expert system for designing the nominal cover thickness by means of fuzzy inference for quantitatively representing the environment affecting factor to reinforced concrete in chloride-induced corrosion environment. In this work, nominal cover thickness to reinforcement in concrete was determined by the sum of minimum cover thickness and tolerance to that defined from skill level, constructability and the significance of member. Several variables defining the quality of concrete and environment affecting factor (EAF) including relative humidity, temperature, cyclic wet and dry, and the distance from coast were treated as fuzzy variables. To qualify EAF the environment conditions of cycle degree of wet-dry, relative humidity, distance from coast and temperature were used as input variables. To determine the nominal cover thickness a qualified EAF, concrete grade, and water-cement ratio were used. The membership functions of each fuzzy variable were generated from the engineering knowledge and intuition based on some references as well as some international codes of practice.

Properties of Unsaturated Polyester Mortars Using Crushed Waste Glass

Abstract The purpose of this study is to explore the use of crushed waste glass as an aggregate in unsaturated polyester (UP) mortar. The unsaturated polyester mortars using crushed waste glass are prepared with three types of fillers, UP-fine aggregate ratios and crushed waste glass replacements for fine aggregate, and tested for weight change, strengths, setting shrinkage and acid resistance. From the test results, the strengths and acid resistance of UP mortars are improved with an increase in the waste glass replacement for fine aggregate. The setting shrinkage of UP mortars has a minimum value of 21.25×10-4 at CWG replacement of 50% for fine aggregate. It is reduced by a factor of two or more compared with 0%. In this study, a UP mortar with fly ash as a filler, a UP-fine aggregate ratio of 15% and a waste glass replacement of 50% for fine aggregate is selected as an optimal mix proportion of UP mortar using crushed waste glass. This is enough to assure the use of the crushed waste glass as an aggregate for the production of UP mortar.

On the Implementation of Fuzzy Arithmetic for Prediction Model Equation of Corrosion Initiation

For critical structures and application, where a given reliability must be met, it is necessary to account for uncertainties and variability in material properties, structural parameters affecting the corrosion process, in addition to the statistical and decision uncertainties. This paper presents an approach to the fuzzy arithmetic based modeling of the chloride-induced corrosion of reinforcement in concrete structures that takes into account the uncertainties in the physical models of chloride penetration into concrete and corrosion of steel reinforcement, as well as the uncertainties in the governing parameters, including concrete diffusivity, concrete cover depth, surface chloride concentration and critical chloride level for corrosion initiation. The parameters of the models are regarded as fuzzy numbers with proper membership function adapted to statistical data of the governing parameters and the fuzziness of the corrosion time is determined by the fuzzy arithmetic of interval arithmetic and extension principle