ULTRA-HIGH STRENGTH CONCRETE: EFFECT OF SUPPLEMENTARY CEMENTITIOUS MATERIALS AND THEIR PROPORTIONS

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ULTRA-HIGH STRENGTH CONCRETE: EFFECT OF SUPPLEMENTARY CEMENTITIOUS MATERIALS AND THEIR PROPORTIONS ABSTRACT   Ultra-High Strength concrete (UHSC) is a new type of concrete known for its superior mechanical properties and durability compared to the normal concrete. However, UHSC is not widely used because of the cost, the large quantity of cement and environmental impact. Therefore, supplementary cementitious materials (SCMs) are used as a partial replacement of cement in order to reduce the cost and limit the effect on the environment. This work investigates the strength of UHSC using multiple series of mixtures taking into consideration different design parameters and considerations. It also studies the impact of the use of diverse types and quantities of supplemental cementitious materials (SCMs), highrange water reducer Sika ViscoCrete-2100 and different water to cementitious materials ratio on UHSC performance. This research was conducted in two phases. During the first phase, the compressive strength of Ultra-High Strength mortar was investigated. The mortar cubes were made using the same percentage of SCMs and same water to cement content, but with different rates of High-range water reducer (HRWR). The SCMs utilized were Silica Fume (SF), Metakaolin (MK), Pumice (PU) grade NCS-3 and grade DS325. Based on the performance of the cubes, another set of mortars were prepared utilizing different percentages (5%, 10% and 15%) of SF and MK only. The compressive strength test was performed according to the specifications of ASTM C109. The second phase evaluates the performance of fresh and hardened UHSC. The density of concrete, compressive strength and splitting tensile strength tests were performed according to the specification of ASTM C138, ASTM C39 and ASTM C496, respectively. Due to the incorporation of supplemental cementitious materials (SCMs), the performance of the mortar cubes and concrete cylinders improved. The test results showed an increase in compressive strength and splitting tensile strength.       TABLE OF CONTENTS     LIST OF FIGURES……………………………………………………………………………………………………. vi LIST OF TABLES……………………………………………………………………………………………………. vii ACKNOWLEDGEMENTS………………………………………………………………………………………. viii CHAPTER 1………………………………………………………………………………………………………………. 1 INTRODUCTION………………………………………………………………………………………………………. 1 1.1  Aim of Study and Motivation…………………………………………………………………………….. 1 1.2  Project Statement……………………………………………………………………………………………… 2 1.3  Thesis Outline………………………………………………………………………………………………….. 2 CHAPTER 2………………………………………………………………………………………………………………. 3 BACKGROUND………………………………………………………………………………………………………… 3 2.1 Literature Review………………………………………………………………………………………………. 3 2.2 Famous Applications of UHSC……………………………………………………………………………. 6 CHAPTER 3………………………………………………………………………………………………………………. 9 MATERIALS AND TEST METHODS………………………………………………………………………… 9 3.1 Materials…………………………………………………………………………………………………………… 9 3.1.1 Cement……………………………………………………………………………………………………….. 9 3.1.2 Supplementary Cementitious Materials………………………………………………………….. 9 3.1.3 Chemical Admixtures…………………………………………………………………………………. 12 3.1.4 Aggregate…………………………………………………………………………………………………. 12 3.1.5 Silica Sand………………………………………………………………………………………………… 12 3.2 Mixing Process………………………………………………………………………………………………… 13 3.2.1 Mortar Cubes…………………………………………………………………………………………….. 13 3.2.2 Concrete Cylinders…………………………………………………………………………………….. 14 3.3 Testing Procedure…………………………………………………………………………………………….. 15 3.3.1 Mortar Cubes Compressive Strength…………………………………………………………….. 15 3.3.2 Density and Air Content Testing of Concrete Cylinders…………………………………. 17 3.3.3 Concrete Cylinder Compression Testing……………………………………………………….. 18 3.3.4 Concrete Cylinder Splitting Tensile Strength Testing…………………………………….. 20 3.4 Mix Design……………………………………………………………………………………………………… 22 3.4.1 Mortar Cubes Mix Design…………………………………………………………………………… 22 3.4.2 Concrete Cylinders Mix Design…………………………………………………………………… 24 CHAPTER 4…………………………………………………………………………………………………………….. 27 RESULTS AND DISCUSSION…………………………………………………………………………………. 27 4.1 Mortar Cubes Compressive Strength Test Results………………………………………………… 27 4.2 Concrete Cylinders Compressive Strength Test Results………………………………………… 38 4.3 Concrete Cylinders Splitting Tensile Strength Test Results…………………………………… 44 4.4 Concrete Cylinders Density and Air Content Test Results…………………………………….. 48 CHAPTER 5…………………………………………………………………………………………………………….. 51 SUMMARY AND CONCLUSIONS…………………………………………………………………………… 51 REFERENCES…………………………………………………………………………………………………………. 53

CHAPTER 1

INTRODUCTION

 

1.1 Aim of Study and Motivation

The concrete industry is continually growing which led to the development of new classes of concrete, and improvement of existing ones. Ultra-high strength concrete UHSC is a new type of concrete known for its superior mechanical properties and outstanding durability and flexibility compared to normal concrete. In general, ultra-high strength concrete (UHSC) is produced using cement, silica fume, quartz sand, quartz powder, steel fibers and superplasticizer. However, other materials are being used lately like fly ash, metakaolin and copper slang. This type of concrete requires the use of very low water to cementitious materials ratio. Therefore, it is recommended to use the best dosages of high-range-water reducers HRWR in order to reduce the water to cementitious materials ratio and ensure the workability of UHSC. Silica fume is primarily used over other pozzolans because it is a highly active pozzolan known for its quick reaction and improves the mechanical characteristics of concrete. Because of its fine particles, it plays the role of a filler for the voids. Also, it improves rheology of the paste and produces high strength hydrates. The benefits of using UHSC in a structure include reducing the dead load due to the superior strength and high shear capacity, sliming the beams, columns, and slabs, increasing durability to resist corrosion due to the freezing and thawing cycle, improving seismic performance by minimizing the weight and decreasing porosity. Despite its advantages, UHSC is not widely used because of the cost, high amount of cement and environmental impact. In order to reduce the cost and minimize the quantity of cement, supplementary cementitious materials (SCMS) are incorporated in UHPC mix design. The use of supplemental cementitious materials (SCMs) improves the performance of fresh and hardened concrete. They increase the strength, ameliorate the workability and durability. In this research, different types of SCMs were used: metakaolin, pumice grade NCS-3 and grade DS- 325 and silica fume. The production of metakaolin Metamax HRM utilized generates approximately 80% less carbon dioxide (CO2) than does production of Portland cement. Thus, the partial replacement of cement by metakaolin will reduce the environmental impact by minimizing the emission of greenhouse gas. In addition, the two grades of pumice used are natural pozzolan and does not contain crystalline silica or hazardous materials.

1.2 Project Statement

Ultra-high strength concrete was developed following the specific principles including use of silica fume to enhance strength, incorporation of fibers to increase ductility, removal of coarse aggregate to improve homogeneity, post-setting heat treatment to develop higher mechanical properties, application of presetting pressure to ensure density and compaction [1] . In this research, an attempt was made to develop ultra-high strength concrete using coarse aggregate instead of quartz sand and quartz powder. In addition to silica fume mainly used in UHSC, other supplementary cementitious materials were also utilized in this study. In ultrahigh strength mortar (UHSM), metakaolin and pumice grade DS325 and grade NCS3 were used. However, UHSC was made by incorporation of percentages 5%, 10%, 15% and 20% of silica fume and metakaolin only. No pre-setting pressure or post-setting heat treatment were used. The samples were cured in standard moist curing room until the age of testing at 7, and 28 day.

1.3 Thesis Outline

This research is presented in four main chapters. The second chapter includes a literature review and practical applications of ultra-high strength concrete (UHSC). The third chapter presents the experimental program. It describes the materials, their chemical and physical properties, in addition to the proportions in different mix designs, and the test methods performed on fresh and hardened concrete. The tests methods discussed include Compressive Strength Test, Splitting Tensile Strength Test, and Density and Air Content Test. The fourth chapter focus on results and discussion of test results for UHSM and UHSC samples through tables, graphs, and interpretations. The fifth chapter concludes with the summary of the research and conclusions. ULTRA-HIGH STRENGTH CONCRETE: EFFECT OF SUPPLEMENTARY CEMENTITIOUS MATERIALS AND THEIR PROPORTIONS

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