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0 MINISTRY OF EDUCATION & TRAINING UNIVERSITY OF TRANSPORT & COMMUNICATIONS LE HONG LAM RESEARCH ON HIGH PERFORMANCE CONCRETE USING SILICA FUME AND NANO SILICA FOR BRIDGE STRUCTURES IN CORROSION ENVIR[.]
MINISTRY OF EDUCATION & TRAINING UNIVERSITY OF TRANSPORT & COMMUNICATIONS LE HONG LAM RESEARCH ON HIGH-PERFORMANCE CONCRETE USING SILICA FUME AND NANO SILICA FOR BRIDGE STRUCTURES IN CORROSION ENVIRONMENTS Major: Special Construction Engineering Code: 958.02.06 SUMMARY OF DOCTORAL DISSERTATION Supervisors: Asoc Prof Phd DAO DUY LAM Prof Phd PHAM DUY HUU Hanoi, 08 - 2022 The thesis is completed at: UNIVERSITY OF TRANSPORT &COMMUNICATIONS Supervisors: Asoc Prof Phd DAO DUY LAM Prof Phd PHAM DUY HUU Reviewer 1: ……………………………………………… …………………………………………………………… Reviewer ……………………………………………… ………………………………………………………… Reviewer 3: ……………………………………………… …………………………………………………………… The thesis is going to be defended in front of the National thesis committee held at ………………………………………………………………… at h ….( month ) … ( date) ……(year) Able to access the thesis in the bibrary: ………………………………… i INTRODUCTION Necessity of the study The transport infrastructure system in general as well as the road, rail and seaport traffic system in particular play a particularly important role in promoting socio-economic development towards industrialization and modernization According to Planning for the 2021-2030 period, vision 2050, building more new traffic systems with 9014km of highway and 29797km of national road; for the seaport system, building 16 seaports in the north and 25 ones in the south Civil works, railways, factories, industrial parks need a huge amount of cement concrete Along with the increase in quantity, the scale of the project is equally modern, requiring materials to manufacture High-Strength Concrete (HSC), High-Perfomance Concrete (HPC) or Ultra High Performance Concrete (UHPC) Nowaday, the research on mixing HSC and HPC concrete mainly uses silica fume or a combination of blast furnace slag fly ash; conventional UHPC concrete combining with steel fiber and carbon fiber have great efficiency The goal of developing a network of road works and a seaport system must adapt to climate change and develop sustainably When building coastal roads and bridges, seaports are directly subject to corrosion of the marine environment such as: chloride ion intrusion, sulphate corrosion, etc., in addition to high strength, must also consider the durability factor to be suitable for the environment In recent years, to study the type of concrete that meets the requirements of high strength and good durability, nanomaterials have also been developed Nanotechnology in concrete is: using the nanometer-sized particles to compact the larger particles to optimize the particle size distribution perfectly, by uniformly combining coarse and fine particles in the mixture The microscopic nanomaterials can fill the gaps between the cement and the silicon soot resulting in a higher level of compaction and produce a more cohesive grout with more calcium silicate hydrate (C-S-H) This greatly increases the mechanical properties and durability of the concrete Several nanomaterials have been studied as concrete admixtures, including nano-silicon (nano-SiO2), nanotitanium (nano-TiO2), nano-alumina (nano-Al2O3), nano-clay, nanoiron (nano-Fe2O3), and nano-CaCO3 Nano silica is one of the first nano-materials used in cement concrete that has great efficiency, adding nano silica to concrete increases pozzolanic activity, more calcium silicate hydrate (C-S-H) is generated produced by the action of calcium hydroxide (CH) from hydration This pozzolanic activity results in a high hardness C-S-H gel that will make the ITZ (interfacial transition zone) microstructure more dense and homogeneous Therefore, it will increase the strength and durability of concrete [18] This improves the strength and durability of the cementitious material by reducing the number of pore sizes, breaking the pore connections and increasing the stiffness of the C-S-H phase [67] Furthermore, silica nanoparticles increase the density of cementitious materials, fill voids and voids, facilitate hydration by acting as central nuclei, the C-S-H gel increases and plays a role important in deflecting and locking cracks [59] In the case of conventional concrete, having nano silica improves the microstructure of the surface area in concrete and mortar Adding nano silica to concrete, two possible reaction mechanisms occur during cement hydration Cement hydration is accelerated when nano silica is added H2SiO2-4 reacts with available Ca2+ to form additional calcium silicate hydrate (C-S-H), these C-S-H particles are spread in water between cement particles and it is like a "germ" that causes the formation of a tighter C-S-H phase The formation of the C-S-H phase is not limited to the particle surface as in pure C3S, but it also takes place in the pore space The formation of a large number of C-S-H particles causes an increase in the early cement hydration rate Furthermore, the puzzolanic reaction of nanosilicon with calcium hydroxide is formed during the hydration process, adding C-S-H which is the main ingredient that increases the strength, density and hardness of the cement At the same time the calcium hydroxide component that did not contribute to the concrete strength development was suppressed In addition to the method of making silica nano from expensive pure chemicals, Vietnam has made nano silica from rice husk ash, which not only solves the problem of environmental pollution but also creates highly effective concrete admixtures According to the practical requirements of developing transport infrastructure systems that require higher and higher quality of concrete, we can think of researching and manufacturing high-quality concrete using nano silica in structural construction bridges, roads, seaports are affected by climate and weather That is the reason why the PhD student chooses the topic of high-quality concrete using nano silica from agricultural by-products for research Thesis title: “Research on high-performance concrete using silica fume and nano silica for bridge structures in corrosion environments” Ojectives Using silca fume, nano-silica and other materials for normal concrete, applying the experimental planning method to design and fabricate high performance concrete owning the optimized compression strength of 70 MPa-concrete Applying high performance concrete using silca fume and nano-silica in beam and estimate life-time of structure Study object and scale Study object: High performance concrete using silica fume and nano-silica; bending beam Study scale: High performance concrete using silica fume and nano-silica of 70 MPa-strength, bending beam U38, estimation of structure life-time Methodology The thesis employs scientific methods as follows Literature review: reference of related thesis, research reports in the field of studying and applying high performance concrete using nano silica, as well as technical specifications, etc… Adoption method: Introducing and adopting former results of high performance concrete using nano silica, published calculation method of concrete beam, U beam structure analysis, specification of ACI 318-14, etc Experimental method: Applying experimental planning and testing mechanical characteristics of high performance concrete using nano silica; testing to estimate the critical moment of bending beam Scientific and Realistic contributions of the thesis * Scientific contribution Studying high performance nano silica–silica fume concrete having high sustainability in bending beam to construct bridges over sea, port structures improves the structure life time, saves the maintenance and repair cost, enhances the safety of concrete and reinforced concrete structures * Realistic contribution The study selected appropriate materials to design and fabricate high performance concrete using silica fume – nano silica delivering the optimized compressing strength of 70 MPa This is the high strength and high sustainability concrete, which can be applied for all concrete and reinforced concrete working in harsh conditions Utilization of agriculture waste like rice hush ash to extract nano silica as the additives for high performance concrete results in economictechinical-ecological benefits Components of the thesis The thesis comprises the Introduction and chapters, and Conclusions Introduction Chapter 1: Review of studying on concrete using silica fume- nano silica Chapter 2: Materials and experimental planning of silica fumenano silica High Performance Concrete Chapter 3: Behavior of bending beam using silica fume- nano silica High Performance Concrete Chapter 4: Applying silica fume- nano silica High Performance Concrete Conclusions and Recommendations REVIEW OF STUDYING ON CONCRETE USUNG SILICA FUME-NANO SILICA 1.1 Overview of High-Performance Concrete using Nano Nanos made from SiO2, Al2O3, Fe2O3, TiO2 or ZrO2 have been studied[40], [63], [84], [85], [86] Nanometer-scale structure to develop multifunctional composite cement materials, with high mechanical quality and high strength, can have many novel properties such as: self-cleaning, self-healing, toughness, and the ability to selfcontrol the cracks [69] The most studied and used in concrete is nano silica (NS) and is also the main topic of many current researches 1.2 Effect of nano silica on concrete properties Adding NS to concrete in addition to compaction also increases pozzolanic activity in which more (C-S-H) is produced by reacting with (CH) during hydration This pozzolanic activity results in a highly rigid C-S-H gel that will make the ITZ microstructure more dense and homogeneous It will increase the strength and durability of concrete [59],[76] 1.3 Research on high-Performance concrete using silica fume and silica nano In the world, nano silica concrete has been studied for several decades and applied to works such as: Garnerplatzbucke Bridge (Germany-2007) Vietnam has only studied for the last few years, mainly using silica nano to make experimental from rice husk ash And the results are quite positive 1.4 Research on structure using silica nano-concrete and concrete durability The studies of T.S Mustafa, J Sridhar [62]…studying the role NS affects the bending behavior of beams Studies on Tran Huu Bang [1], Forood Torabian Isfahani[47]…study on chloride corrosion resistance 1.5 Conclusion Chapter Silica nano particles in the concrete mix act as "fillers" to fill the voids and voids in the concrete mix of larger particle sizes, thereby increasing the density, reducing porosity, makes the microstructure denser in the Interfacial transition zone (ITZ) between the aggregate and the cement paste Cemented concrete with NS will react in the hydration of cement NS produces H2SiO2-4 reacting with Ca2 + generated by Ca(OH)2 will form additional (C-S-H), making concrete using NS change from mechanical properties to durability of concrete according to Positive direction: Compressive strength, tensile strength when bending, permeability, anti-corrosion, anti-cavitation all increased a lot compared to concrete without using NS Most of the research results on concrete using nano silica in the world give very good results on this material In Vietnam, the initial research results on the application of silicon nano have positive results, however, the research data is quite small and has not been studied in depth to apply high quality concrete to concrete and reinforced concrete structures or bridges Most of the research results give the optimal value of nano silica content in the range of 1-3% CKD The thesis will choose to study using NS content varying in the range of 1,2 to 2,8% CKD to design high quality concrete mix with strength of 70MPa In order to optimize the NS content and reduce the cost for experiments, the thesis will use the experimental planning method to find the optimal NS content, satisfying the technical requirements of high performance concrete MATERIAL AND EXPERIMENTAL PLANNING OF SILICA FUME-NANO SILICA HIGH PERFORMANCE CONCRETE 2.1 Materials Cement: PC40 of But Son Silica fume (Sikacrete PP1) of Sika Vietnam Nano silica is fabricated from rice husk ash at the Research Center of Applied Chemistry, University of Water Resources Crushed stone: Kim Bang - Ha Nam Sand: Song Lo-Phu Tho Additives Sika Viscocrete 3000-20M Water: conforms to the standard TCVN 4506:2012 2.2 Experimental planning affects the ratio of N/CKD and content of Nano silica to compressive strength and chloride ion permeability 2.2.1 Parameters Objective function: compressive strength and chloride ion permeability Influential factors: X1: Ratio of Water/CKD; X2: % Nano silica Table 2-8 Values and ranges of influencing factors Value X1 X2 Range 0,26 ≤ X1 ≤0,34 1,2 ≤ X2 ≤2,8 X0j 0,3 2,0 ΔXj 0,04 0,8 2.2.2 Experimental planning of the correlation between the real code and the coded variable Make an experimental table of correlation between the real coding and the coding variable, the experimental plan at the center, according to references [15] 2.2.3 Design of cement concrete mix according to ACI211.4R-08 Standard Research and selection of elements in the design of the mix according to ACI211.4R-08 standard [27] 2.3 Experimental design of silica fume-nano silica concrete Carry out experimental design to mixture according to the Section 2.2.3, mixture as shown in Table 2-21 Table 2-21 Composition mixture according to experimental plan No Sign C026-12NS C026-20NS C026-28NS C030-12NS C030-20NS N/ CKD 0,26 0,26 0,26 0,3 0,3 Đ (kg) 1060 1060 1060 1060 1060 C (kg) 613 590 610 664 662 N (lit) 160,4 160,4 160,4 160,4 160,4 X (kg) 538,5 555,3 529 485,8 481,5 SF (kg) 47,4 49,4 47,4 42,8 42,8 NS (kg) 7,1 12,34 16,6 6,4 10,7 PGSD (lít) 7,1 7,4 7,1 6,4 6,4 concrete is ignored (see Section 10.2.5 of ACI) Compression zone concrete: For rectangular compression zone with width b and height to neutral axis c 3.1.3 Building the relationship between moment and curvature in flexural beams Building the relationship between moment and curvature on the basis of the theory of ACI318 standard and analysis of sectional section of flexural members (Park and Paulay [92]) From formula (37) to (3-20) M Mu My h ds As a0 Mcr cr.a cr.b y b u Figure 3-6 Relationship between moment and curvature in single-reinforced flexural beam a Ultimate moment M u = 0,85 f 'c ab d s − 2 Ultimate curvature u = c c1 = c a (3-19) (3-20) 3.2 Experimental beams and data collection 3.2.1 Preparation of test beam samples According to the design of the mix (optimal) Table 2-21 3.2.2 Producing test beam samples 130 300 130 5x60=300 20 Figure 3-11 Reinforcement structure and location of 9-beam 70 1060 70 20 110 20 150 150 150 11 20 110 20 20 110 20 130 150 1200 20 150 5x60=300 20 110 20 20 test equipment 3.3 Method and sequence of beam testing 3.3.1 Experimental equipment Compact DAQ Multifunction System (Compact DAQ Multifunction System) National Instruments (USA) 3.3.2 Experimental process Conducted compression of beam samples to collect Load, displacement, and deformation of concrete in the compression zone, steel in the tensile zone by load cell, LDVT, strange gauge Figure 3-17 Conduct experiments Figure 3-18 Load-deflection diagram for beam group 2D12 Collect beam test results 3.4 The data collected for beams 2D12-1 is shown in Table 3-3 Table 3-3 Typical data collected for beams 2D12-1 The point Load (KN) A B C 1,13 21,35 49,48 58,52 3.5 BEAM 2D12-1 Displacement Tensile steel between beams deformation s (mm) 0,037951 0,000016 0,798672 0,000096 6,21878 0,002344 23,982055 0,011328 Concrete compressive deformation c 0,000001 0,000230 0,001737 0,008362 Load and deflection chart The relationship load - deflection is shown in Figure 3-18 to 3-21 3.6 Comment The behavior of beams is divided into stages: Elastic phase without cracks (Type OA on the graph) The crack period until the 12 steel reaches the yield (Section AB) The period after the steel yield to failure (Section BC) Figure 3-18 3.7 Calculation of ultimate moment according to theory and experimental results Calculation of the theoretical ultimate moment Mu using the parameters determining the equivalent rectangular compressive concrete block proposed by ACI 318-14 (2014), CEB-FIP MC90 (1991), CSA A23.3-04 (2004) and NZS 3101-95 (1995), as shown in Table 3-5 Formula: M u = f 'c 1 cb ( d s − 0,51 c ) (3-21) Calculate the experimental ultimate moment Mu by mechanical methods as shown in Figure 3-22 P/2 70 380 P/2 300 380 70 1200 Figure 3-22 Calculation diagram of the ultimate moment of beams Tables 3-8 Analytical and experimental results and ultimate moment values according to standards MTN Beam 2D12-1 2D12-2 2D12-3 2D14-1 2D14-2 2D14-3 2D16-1 2D16-2 2D16-3 11.20 11.48 11.35 14.42 14.86 14.78 17.18 17.54 17.36 average ACI 318 Mu k=(MTN (KN.m) /Mu) 9.98 9.7 9.8 13.1 12.8 13.1 15.6 15.8 15.8 1.12 1.19 1.16 1.08 1.16 1.12 1.10 1.11 1.08 1.12 CEB-FIB MC90 Mu k=(MTN (KN.m) /Mu) 9.76 9.4 9.6 12.7 12.4 12.7 15.0 15.1 15.1 Comment 13 1.15 1.22 1.18 1.12 1.19 1.15 1.14 1.15 1.12 1.16 CSA A23.3-04 Mu k=(MTN (KN.m) /Mu) 9.92 9.6 9.8 13.0 12.7 13.0 15.5 15.6 15.6 1.13 1.20 1.16 1.09 1.17 1.13 1.11 1.12 1.09 1.13 NZS 3101-95 Mu k=(MTN (KN.m) /Mu) 9.91 9.59 9.8 13.0 12.7 13.0 15.4 15.6 15.6 1.13 1.20 1.16 1.09 1.17 1.13 1.11 1.12 1.09 1.13 There is a big difference between the experimental and the standard ultimate moments, the average experimental value is 12-16% Thus, we can see that these calculation theories ignore the work of the concrete tensile area that may not be suitable for the actual working of this type of concrete 3.8 Building the theoretical basis and calculating the experimental resistance taking into account the tensile zone of concrete 3.8.1 Building the theoretical basis for determining the height of the tension zone of concrete Consider the tensile concrete as a rectangular block, the height is x and the tensile strength is ft 0.85f'c 0.003 a=1.c c ft ds x r As.fy b As.fy Figure 3-24 Hypothetical model of working concrete in flexural strength considering the tensile zone The balance equation taking into account the tensile zone of concrete: X = 0,85 f 'c a b = A s f y + x b f t a a x a M / = M u = A s f y d s − + x b f t − + 3.8.2 (3-23) Construct an equation for the relationship between x and a From experimental values of Mu instead of the system of equations (3-23), the regression equation for the height of the tensile zone x is determined by the height of the compression zone a: 14 x = 33, 737 + 0,325 a (3-33) 3.8.3 Comment Proposing an equation for determining the ultimate moment for high-quality concrete using nano silica with a design strength of 70MPa: a a x a M u = As f y ds − + x b f t − + 2 1 2 (3-34) With: Tensile concrete stress block is (x.ft) 3.9 Relationship is between moment and curvature 3.9.1 Constructing the theoretical moment and curvature relationship Proceed to build the relationship moment and curvature for the beam 2D12-1 on the cross-sectional parameters as in section 3.8.1 Apply formulas (3-6) to (3-20) 3.9.2 Determine the ultimate moment and curvature according to the empirical formula taking into account the tensile concrete region Based on the formulas in Sections 3.9.1 and 3.9.2, calculate the corresponding moment and curvature values for beams as shown in Table 3-12 Table 3-12 Table of values of moment and theoretical curvature Beam 2D12-1 2D12-2 2D12-3 2D14-1 2D14-2 2D14-3 Value M (KN.m) (rad/mm)x10-5 M(KN.m) (rad/mm)x10-5 M(KN.m) (rad/mm)x10-5 M(KN.m) (rad/mm)x10-5 M(KN.m) (rad/mm)x10-5 M(KN.m) (rad/mm)x10-5 Mcr.a 5.32 0.24 5.28 0.24 5.38 0.24 5.41 0.24 5.35 0.24 5.39 0.20 15 Mcr.b 5.32 1.11 5.28 1.19 5.38 1.15 5.41 0.89 5.35 0.96 5.39 0.92 My 9.64 1.85 9.34 1.92 9.57 1.87 12.95 1.90 12.44 1.98 12.75 1.93 MACIu 9.97 28.18 9.64 28.18 9.89 28.18 13.35 20.83 12.80 20.83 13.13 20.83 Mftu 11.39 17.23 11.06 17.23 11.30 17.23 14.90 14.07 14.34 14.07 4.68 14.07 Beam 2D16-1 2D16-2 2D16-3 3.9.3 Value M(KN.m) (rad/mm)x10-5 M(KN.m) (rad/mm)x10-5 M(KN.m) (rad/mm)x10-5 Mcr.a 5.46 0.20 5.70 0.25 5.45 0.24 Mcr.b 5.46 0.78 5.70 0.83 5.45 0.79 My 15.41 1.93 15.29 1.95 15.29 1.95 MACIu 15.88 16.77 15.75 16.77 15.75 16.77 Mftu 17.55 12.02 17.41 12.00 17.41 12.02 Experimental curvature value Based on Bernoulli's principle, refer to [92] for experimental results of beams obtained from strain gauges mounted on tensile steel and compressive concrete in the mid-span section Calculation of curvature according to Figure 2-36 c kds Trục trung hoà neutral axis ds s Figure 3-27 Diagram of the Figure 3-26 Calculation of relationship ultimate moment experimental curvature and curvature 2D12-1 beam Table 3-13 Moment value and experimental curvature of 2D12-1 Point A B C Load MTN Tensile steel deformation s KN KN.m 1.13 0.22 21.35 4.06 49.48 9.40 58.52 11.12 3.9.4 0.000016 0.000096 0.002344 0.011328 Concrete compressive deformation c 0.000001 0.000230 0.001737 0.008362 Experimental curvature Rad/mm(x10-5) 0.0136 0.2608 3.2650 15.7506 Experimental and theoretical curvature chart Figure 3-27 Show the chart of ultimate moment relationship and beam curvature 2D12-1 16 3.9.5 The ductility of the research beam According to Park and Paulay [92], the ductility of the structure is usually denoted by u and is defined by the plastic ratio according to the following formula: u = u / y Figure 3-36 can be calculated Figure 3-36 Relation of ductility ratio and reinforcement content of experimental beams The plastic ductility of the studied concrete is quite high, which is suitable for structures subjected to dynamic loads 3.9.6 Comment In general, the results of the graphs show that the momentcurvature curves between the improved analytical method and the experimental method are similar 3.10 Conclusion of chapter Developing an improved ultimate moment equation considering the tensile region of high-quality concrete using silica fume and nano silica: a a x a M u = As f y d s − + x b f t − + 2 1 2 x.ft: Assumptive tensile concrete block The height of the tension area x is determined by the height of the compression area a: x = 33, 737 + 0,325 a 17 From Figure 3-27 to Figure 3-35, the relationship between the moment and the corresponding curvature of the beam cross-section at the mid-span section is shown by analytical and experimental methods The results of the graphs show that the moment-curvature curves between the improved analytical method and the experimental method have a very clear similarity in the two working stages of the section: the elastic phase before cracking and the molten steel stage until failure Most of the samples showed that the deviations at the crack point and the limit point between the two methods are similar, which can show the reliability of the correction method proposed by the study APPLYING SILICA FUME- NANO SILICA HIGH PERFORMANCE CONCRETE 4.1 Beam structure U38m The thesis analyzes the bending resistance of the U-section Figure 4-1, length 38m, using 77 strand of 15,2mm cable with low slack Calculating the flexural resistance of non-NS concrete beams and using 2% NS taking into account the tensile strength of the concrete, results in Table 4-6 Table 4-6 Table of results for beams U38m Tham số/ Parameters f'c Eb Ed h h2 b'f h'=h+h2 k 1 U38-C70 70 26752 42299 1400 232,3 2212 1632,3 0,28 0,65 18 U38-C70-2NS 93 50946 50946 1400 232,3 3305,6 1632,3 0,28 0,65 ... Several nanomaterials have been studied as concrete admixtures, including nano- silicon (nano- SiO2), nanotitanium (nano- TiO2), nano- alumina (nano- Al2O3), nano- clay, nanoiron (nano- Fe2O3), and nano- CaCO3... using silica fume- nano silica Chapter 2: Materials and experimental planning of silica fumenano silica High Performance Concrete Chapter 3: Behavior of bending beam using silica fume- nano silica... nano- CaCO3 Nano silica is one of the first nano- materials used in cement concrete that has great efficiency, adding nano silica to concrete increases pozzolanic activity, more calcium silicate