Summary of doctoral dissertation Effect of initial physical properties of roller compacted concrete to construction schedule of concrete gravity dam in Vietnam

MINISTRY OF EDUCATION AND TRAINING MINISTRY OF AGRICULTURE AND RURAL DEVELOPMENT THUY LOI UNIVERISITY LE QUOC TOAN EFFECT OF INITIAL PHYSICAL PROPERTIES OF ROLLER COMPACTED CONCRETE TO

MINISTRY OF EDUCATION

AND TRAINING

MINISTRY OF AGRICULTURE AND RURAL DEVELOPMENT

THUY LOI UNIVERISITY

LE QUOC TOAN

EFFECT OF INITIAL PHYSICAL PROPERTIES OF ROLLER COMPACTED CONCRETE TO CONSTRUCTION SCHEDULE OF

CONCRETE GRAVITY DAM IN VIETNAM

Major: Hydraulic engineering

Code No: 62.58.40.01

SUMMARY OF DOCTORAL DISSERTATION

HANOI, 2016

This scientific work has been accomplished at: Water Resources University

Supervisor 1: Prof.Dr Vu Thanh Te

Supervisor 2: Assoc.Prof.Dr Do Van Luong

Reviewer 1: Assoc.Prof.Dr Nguyen Thanh Sang

Reviewer 2: Assoc.Prof.Dr Vu Huu Hai

Reviewer 3: Assoc.Prof.Dr Hoang Pho Uyen

This doctor dissertation will be defended at university graduate council of Thuy Loi Univeristy

At h00, date month year 2016

It is possible to find out information about this document at:

- National Library of Vietnam

- Library of Thuy Loi University, Hanoi

INTRODUCTION

1 Reasons for choosing the research

The outstandingly advantages of Roller Compacted Concrete (RCC) are faster speed of construction, lower price At present, its applications have been quite common in Vietnam Almost the principal calculations in design and construction of RCC Dam inherited from basic concepts of normal concrete or taking from foreign documents Recently, there have been some incidents happened at main dam of RCC dams, but no evaluations or deeply summaries addressed

Even though the scientific evident and theoretical calculations in applications of RCC technology used in Vietnam, but there is lack of in-depth research The studies about construction schedule of RCC dams are vital in order to make projects become more reasonable and effective

2 The Purpose of Research

This study focus on the behaviour and quantify initial physical properties of RCC, from the beginning of hydration to designated characteristic of RCC, in order to define the thermal evolution, thermal stresses By doing this, the appropriate speed of construction can be established when building RCC dam project

- RCC technology has been applied on more than 20 concrete gravity dam in Vietnam However, the quality of these buildings have not considered properly

and researched in systematical way Therefore, results of this study aim to determine the method, providing reliable calculation tools for the design and construction of RCC It is also suggested solutions to monitor, repair and ensure the safety for constructed buildings and under construction projects

7 New aspects of Research

This study has gained new points as follow:

Find out information about relationships of two RCC aggregate gradation such

as compressive strength development over time, tensile strength development over time, shrinkage strain over time, Elastic Modulus of Concrete over time Completing and supplementing thermal evolution calculation and thermal stresses in ANSYS software in order to using as a tool for inspecting the construction speed of Dong Nai 4 dam

8 Structure of Dissertation

This dissertation includes introduction, four chapters, conclusion and discussions 49 references, 04 authority publications The main content of the document presented in 144 pages, with 69 tables, 116 figures and 06 appendices

CHAPTER 1: OVERVIEW OF ROLLER-COMPACTED CONCRETE AND RESEARCH QUESTIONS AND OBJECTIVES

1.1 History and development of roller compacted concrete in the world

1961, it was first used at Alpe Gera dam - Italia, Manicongan dam – Canada and Thach Mon - Taiwan;

1970 there is research about RCC in America; 1980 Willow Creek dam was built at Oregon state with a height of 52 m, and a length of 543 m, constructed

of roller-compacted concrete;

1970 England, Dunstan, the Construction Industry Research and Information Association (CIRIA) carried out studies for high fly ash content RCC, testing at Water Treatment Plant Tamara – Coruwall (1976) & Wimbledall (1979);

1974, Japan began research about RCC and Shimajigawa dam, 89 m high and 240m length, was the first Japanese RCC dam with 165,000m3 placed RCC in total of 317,000m3 concrete for this dam 1980, China researched and applied RCC technology; so far China is now the leading country of the world in the construction RCC dams;

1.2 Construction of RCC dam in Vietnam

From 1996 to 2006, the number of RCC dams with higher cemetious content increased from 43.3% in 1996 to 47.4% in 2002 and 53.4% in 2006 Since December 2005, total 285 RCC dams have been constructed

1.3 Researches of Roller-Compacted Concrete in Vietnam

Vietnam has been researched about RCC dams since 1990 In 2003, Pleikrong hydraulic dams is the first RCC buildings in Vietnam Until now, there were more than 20 gravity concrete dams completed or being under construction by using RCC technology

1.4 Literature review of RCC research in Vietnam and the world

1.4.1 Literature review of RCC research in the world

1.4.1.1 Findings of roller compacted concrete in France

From 1988 to 1996, France has implemented research projects nationally Bacara

of RCC dam [4]

1.4.1.2 Findings of roller compacted concrete in US

The American Concrete Institute: provide high speed of construction and cost savings, but seepage and cracks easier occur easily

1.4.1.3 Findings of roller compacted concrete in Japan

RCC has quality of waterproofing and strength as CVC

1.4.1.4 Findings of roller compacted concrete in China

The method of RCCD in China based on the experience and lessons of two approaches RCD and RCC combined with fly ash additives available in domestic market

Research about construction technologies for RCC: documents [26], [27], [28], [29]

1.5 The remaining issues of RCC research, objective of dissertation

1.5.1 The remaining issues of RCC research

- Improving the quality combined with surface layer to satisfy dam height

- The quality of combined surface layer is a cause of seepage

- The RCC construction schedule: it depends on thermal evolution, thermal stress, which ensure anti cracking ability of dam These factors directly influenced by the initial physical parameters of RCC Therefore, research is necessary to determine a reasonable construction schedule while building RCC dams

1.5.2 Research orientation content of this research

To select materials for RCC aggregate gradation, provide experimental method

to figure out physical properties of RCC by current codes

To carry out experiments to manufacture 02 RCC aggregate gradation, which commonly use in Middle and South of Tay Nguyen, namely pozzolanic active mineral RCC and fly ash active mineral RCC

Design of experiments to figure out the development of RCC initial physical properties of 2 optimum aggregate RCC over designated time by using non-linear functions

Integrate ANSYS to calculate the heat & thermal stress in RCC dams

Using integrated ANSYS to find out the appropriate construction speed based

on temperature control and thermal stresses in RCC dam

Research Process Flowchart shown in Figure 1.1

Figure 1 1 Research process of Construction Schedule of RCC

CHAPTER 2 SCIENTIFIC BASIS AND EXPERIMENTAL METHODS

TO DETERMINE AGGREATE GRADATION & PHYSICAL

PARAMETORS RCC

2.1 Factors affecting the physical parameter of RCC

The characteristic of materials manufactured RCC

Ingredients of aggregate gradation RCC

2.2.1 Materials used for grading RCC-P (pozzolanic additives)

- Concrete: concrete PCB40 Fico, TCVN 6260: 2009 [30]

- Pozzolan: mine number 4A Dak Nong, TCVN 8825: 2011 “Mineral

admixtures for RCC” [31]

- Water: TCVN 4506: 2012 "Water for mixing concrete and mortar - Technical

specification” [32]

- Small aggregate: in Dak Nong, TCVN 7570: 2006 and ASTM C29: 2003

- Crushed stone: in Dak Nong, TCVN7570:2006“Aggregates for concrete and

mortar - Specifications”

- Plasticizers and set-controlling admixtures: Plastiment 96, ASTM C494 type

D

2.2.2 Materials used for grading RCC-T (RCC using fly ash additives)

- Concrete: concrete PC40 Ha Tien 1, TCVN 2682: 2009 [34]

- Fly ash: Formosa, TCVN 8825: 2011 “Mineral admixtures for RCC”

- Water: TCVN 4506: 2012 "Water for mixing concrete and mortar - Technical

specification”

- Sand: in Ninh Thuan, TCVN7570:2006“Aggregates for concrete and mortar - Specifications”

- Crushed stone: in Ninh Thuan, TCVN7570:2006“Aggregates for concrete and

mortar - Specifications”

- Fine admixtures: Non-active fillers, about 15% of the volume of sand

- Plasticizers and set-controlling admixtures: Plastiment 96, ASTM C494 type

D

2.3 Determine the optimum gradation RCC

2.3.1 Method to determine the optimum gradation RCC

This study use the method to design gradation ACI 211.3R-2002 [5], using

experiments and theory "Experimental planning" to figure out the optimum

gradation RCC, especially in strength and using materials

2.3.2 Experimental planning theory in determine gradation RCC [35]

2.4 Methods to determine physical properties of RCC

The experimental procedure show in Figure below:

Figure 2.3 Experimental procedure determine the physical properties RCC

(There are 6 physical factors found in this procedures through headings 2.4.1 to

2.4.6, namely standard, sample and experimental apparatus; formula to

determine these properties)

2.5 Determine optimum aggregate gradation RCC

2.5.1 Planning manipulate experimentally determined gradation

2.5.2 Determine optimal aggregate gradation RCC-P

Ratio: mineral admixture/ adhesives = 0.63, 0.65 and 0.67; water/ adhesives =

0.56; 0.58 and 0.60; adhesives = 190 kg/m3; Sucking sand level Sand/(sand+

crushed stone) = 0.37; mineral admixtures = 1.8 liter/100kg adhesives

Material

of

RCC

Test Specimens

Experim ental Results

Define Propert ies

Curing Test Specimen

Formula Summary

Table 2 1 Table encryption empirical coefficient

Table 2 2 The composition of aggregate RCC - P empirical

Case Variable code

Real variable Consumption materials for 1 m 3 (Kg) V c

The regression equation for compressive strength of 365 days (2.1):

Rn365 =+15,26 - 0,12X1 – 0,10X2 + 0,047X1X2 – 0,061X1 + 0,014X2

The rate of mineral admixture/adhesives and rate of water/adhesives saw influences to strength of RCC, by following results:

Figure 2.12 The correlation of

MA/adhesion and ratio Water/adhesion

of Rn365 RCC-P

Figure 2.13 The correlation contour plots of MA/adhesion and ratio Water/adhesion of Rn365 RCC-P The optimum aggregate gradation RCC-P: Cement: 75kg, mineral admixtures: 115Kg, sand 804kg, crushed stone 4, 75÷19 (mm): 722kg crushed stone 20÷50 (mm): 670kg, water 110 liter, chemical admixture 3.4 liter

2.5.3 Determine optimal aggregate gradation RCC-T

Ratio of admixture/ adhesives: 0.58; 0.6 and 0.62; water/ adhesives:0.56,0.58 and 0.6.Adhesives=200kg Admixtures:15% weight of sand; Sucking sand level Sand/(sand+crushed stone)=0.34; chemical admixture=1.0 liter/100kg/adhesive The regression equation for compressive strength of 365 days (2.2):

Rn90 = - 785,34+1291,5X1+1471,34X2+ 231,25X1X2 - 1204,06X12 - 1391,56X22

Figure 2 16 The correlation of

MA/adhesion ratio and Water/adhesion

ratio of Rn90 RCC-T

Figure 2 17 The correlation contour plots of MA/adhesion ratio and Water/adhesion ratio of Rn90 RCC-T Optimum gradation of RCC-T: Concrete: 80kg, Mineral Admixture: 120Kg, sand 687 kg; crushed stone: 5÷19 (mm): 479kg, 20÷39 (mm): 295kg, 40÷60 (mm): 628kg, water 115 liter, Chemical Admixture 2 liters

CHAPTER 3 RESEARCH THE DEVELOPMENT OF SOME INITIAL PHYSICAL PARAMETER OF ROLLER COMPACTED CONCRETE 3.1 Research the development of some initial physical parameter of roller compacted concrete

3.1.1 Research the development of compressive strength of RCC (R n )

The correlation function show the development of Rn for gradation RCC-P: Yn1

= 2.64ln(x) + 2.24 with R2= 0.9 (3.1a); gradation of RCC-T: Yn2 = 4.54ln(x) + 2.52 với R2= 0.93 (3.1b)

Table 3 3 Compressive strength of RCC-P by calculations

Compressive strength (Mpa) 2.24 5.14 6.49 7.38 9.21 10.4 12.87 14.12

% discrepancy with the previous day 26.30 9.99 5.84 10.68 19.87 16.58 9.73

Table 3 4 Compressive strength of RCC-T by calculations

Compressive strength (Mpa) 2.52 7.51 9.83 11.35 14.5 17.65 20.8 22.95

% discrepancy with the previous day 32.48 11.49 6.57 11.77 21.70 17.83 10.36

Figure 3.3 Compressive strength ~ time for 2 gradation RCC-P& RCC-T

3.1.2 Research the development of tensile strength of RCC (R K )

The correlation function show the development of Rk for gradation RCC-P:

Yk1 = 0.258ln(x) + 0.029 with R2 = 0.9764 (3.2a) for gradation RCC-T:

Yk2 = 0.289ln(x) + 0.051 with R2= 0.971(3.2b)

Table 3.7 Compressive strength of two gradation RCC-P&RCC-T according

two correlation and regression

Figure 3.6 Correlation of Rk by ages of RCC-P&RCC-T

Table 3.8 Compare the increasing speed of tensile strength, compressive

strength of RCC Gradation Rn28 Rn90 Increasing rate

Increasing rate (%)

3.1.3 Study of Shrinkage strain of RCC

3.1.3.1 Study of thermal shrinkage strain of RCC

Figure 3.7 The development of thermal at some points of RCC sample

3.1.3.2 Study of thermal coefficient of RCC

Table 3.12 Some thermal coefficient of RCC

Original of

Aggregate

Water/(Cement Mineral Additives)

Water (Kg/m 3 ) Coef BDN 10

3.1.3.3 Research shrinkage due to dehydration (dry shrinkage) of RCC

Table 3.13 Volumetric shrinkage of RCC

Coefficient of Volumetric shrinkage Cn (%*10 -2 )

Ycn1 = 0.0075ln(x) + 0.0057 with R2= 0.9216 (3.3a); gradation BTĐL-T:

Ycn2 = 0.0057ln(x) + 0.005 with R2= 0.9116 (3.3b)

3.1.4 Heat transfer coefficient, Coefficient of thermal conductivity

3.1.4.1 Heat transfer coefficient

Heat transfer coefficient (HSTN) shows the diffusion of heat from concrete (unit

m2/h and was marked as a) The bigger value of HSTN, the less time require to

temperature at points of concrete sample reach same values HSTN of concrete depends on type of aggregate, the amount of aggregate, amount of water and weight of concrete Generally, HSTN has the reverser trend when temperature increase, but it has the same pattern with proportion of aggregate in concrete The reason for this is that RCC used less water and more aggregate than CVC so that HSTN of RCC larger than CVC, but the different are not so significant [41]

3.1.4.2 Coefficient of thermal conductivity

 =  C γ; with  is Coefficient of thermal conductivity of concrete [KJ/(m.h 0C)]; : HSTN(m2/h); C: heat capacity of concrete [KJ/(Kg.0C)]; γ: Weight of concrete [Kg /(m3)]

Table 3.14 Research results on the thermal characteristics of RCC

3.1.5 Research Elastic modulus of RCC

3.1.5.1 Static Elastic modulus (EM) in compression

Figure 3 13 Evolutions of EM of RCC-P & RCC-T