Hydrodemolition of Concrete Surfaces and Reinforced Concrete

269 Pages·2005·15.782 MB·English

by  Andreas W. Momber (Auth.)

tsiL of desu slobmys
dna abbreviations
contact radius
tl
A cutting rate
*A jet structure parameter
cA pore cross section
An hydrodemolished area
A N nozzle (orifice) cross section
pA plunger cross section
vibration parameter (acceleration)
a V
b jetting tool geometry parameter
*B jet structure parameter
MB brittleness
speed of sound water
c F
speed of sound target
c M
pC constant
sC interlock cohesion parameter
shock wave velocity
c W
D sand section test parameter
a. drop diameter
d maximum drop diameter
Dmax
Sauter diameter (water drop)
Fd focus diameter
a.
hose diameter
al
jet diameter
Ma material grain diameter
G nozzle (orifice) diameter
od pore diameter
~a
plunger diameter
sa particle diameter
~d threshold diameter
kinetic energy hydro-abrasive jet
EA
BE basic output
DE drop disintegration energy
LEE elastic strain energy density
HE hydrodemolition efficiency
x Hydrodemolition of etercnoc surfaces dna decrofnier etercnoc structures
E l kinetic energy water jet
E M Young's modulus material
Ep Young's modulus particle
E s kinetic energy abrasive particle
Esp specific energy
E T threshold energy
E v volumetric efficiency
F c contact force
fd frequency pulsating liquid jet
F F frictional force
fN nozzle oscillation frequenvy
Fp plunger rod force
F R reaction force
g acceleration due to gravity
ciG critical crack extension force
G F fracture energy
H geodetic height
h L erosion depth
h M depth of cut
H M micro hardness
h e water penetration depth
H s stroke
l/. w critical depth of cut
Ij jet impulse flow
k internal roughness
*K pressure distribution parameter
czK fracture toughness
kp permeability
1 c crack length
L c characteristic length
1 F focus length
1 u hose length
L R radial crack length
m fracture toughness power exponent
hr A abrasive mass flow rate
m M mass loss
th~ water mass flow rate
n velocity power exponent
n c crank-shaft speed
N D drop number
N M machinability number
Np plunger number
N R number of radial cracks
n s erosion/cutting steps
N s particle number
Oh Ohnesorge number
List of used symbols and abbreviations xi
P pressure
AP atmospheric pressure
%
power density water jet
HP hydraulic power
lp cavitation pressure
jet power
porosity
PM
oP optimum pressure
pR pressure at crack tip
rP pore perimeter
sP stagnation pressure
TP theoretical hydraulic power
threshold pressure
PT
vP pressure loss
actual volumetric flow rate
loss in volumetric flow rate
nominal volumetric flow rate
theoretical volumetric flow rate
s_O penetrating water volume
w_O water volume
w_O volumetric flow rate water
transition radius
r C
eR Reynolds number
ER specific erodability
mixing ratio
R M
oR bubble radius
pR pressure ratio
radial distance nozzle - rotational centre
r T
roughness depth
R t
dS Strouhal number
sound impedance
s M
Sv 1 water jet velocity standard deviation
t u working time
Ft exposure time
ot optimum exposure time
pt impact duration
uT turbulence
V sand section test parameter
theoretical jet velocity
v o
crank-shaft circumferential velocity
v C
drop velocity
v D
velocity of entrained water
v E
flow velocity
v F
material grain volume
threshold velocity for crack formation
v H
xii Hydrodemolition of concrete surfaces and reinforced concrete structures
v/ jet velocity
vj average water jet velocity
volume removal
volumetric removal rate
nozzle (orifice) flow velocity
V N
average plunger speed
Vp
velocity for plastic flow
VpL
elastic threshold velocity
V R
abrasive particle velocity
V S
threshold velocity
V t
traverse rate
V T
crack opening displacement
W
W water consumption
We Weber number
WM removal width
jet length; stand-off distance
X
water jet core length
X C
critical jet length
X L
water jet transition zone length
XTR
Y traverse increment
!to optimum traverse increment
ap hose pressure loss
AP power loss
nozzle (orifice) flow parameter
~O
Aa abrasive mixing efficiency parameter
crank-shaft angle
a C
gas content
a G
La fracture geometry parameter
dowel parameter
a S
X cutting pass parameter
RX reinforcement cutting parameter
.g efficiency parameter
r impact angle
R-curve parameter
7 jetting tool angle
specific surface energy
M7
oir pump efficiency
tic elastic parameter (compressibility)
Fir kinematic viscosity water
ric volumetric rating parameter
hir hydraulic efficiency
Mir mechanical efficiency
Tir transmission efficiency
Vir volumetric efficiency
c~ s friction parameter
List of used symbols and snoitaiverbba xiii
nozzle (orifice) efficiency parameter
Fv dynamic viscosity water
MV Poisson's ratio target material
pV Poisson's ratio particle
nozzle (orifice) angle
LP density air
MP density target
SP density particle
WP density liquid
ac compressive strength
% impact stress (water hammer pressure)
flow stress
Fa surface tension water
tensile strength
ay yield stress
s~ shear stress
*O_( water penetration parameter
rotational speed
3O T
compressibility parameter
hose friction number
volume loss parameter
CHAPTER 1
Introduction
1.1 Introductory remarks
1.2 Industrial applications
1.2.1 Civil and construction engineering
1.2.2 Industrial cleaning
1.2.3 Environmental engineering and other applications
1.3 Subdivision of water jets
1.3.1 Definitions and pressure ranges
1.3.2 Fluid medium and loading regime
1.4 Failure behaviour of cementitious materials
1.4.1 Structure and properties of cementitious materials
1.4.2 Fracture behaviour of cementitious materials
2 Hydrodemolition of surfaces concrete and concrete reinforced structures
1.1 Introductory remarks
The formation and utilisation of water jets are not human discoveries. As with
many other engineering discoveries, the principle was already known and utilised
in nature. A process that is comparable with water jetting is the "spitting" of some
fish species, namely Colisa chuna, Colisa lalia, and Toxotes jacularix. The latter
species uses some type of discontinuous water jets for spitting for feeding. The other
species show spit behaviour in case of nest building, fry tending, and owing to
excitement. An example is shown in Fig. 1.1 a. Detailed investigations are provided
by L/iling ( 1958, 1969) and Vierke (19 73). Another example of how water jets are
utilised in nature is provided by the snapping shrimp. Snapping shrimps produce a
fast, well focused water jet by rapid closure of their specialised snapper claw
(Versluis et al., 2000). One of the effects of the snapping is to stun or kill pray
animals. Main water jet velocity was measured to be 6.5 m/s (Herberholz and
Schmitz, 1999). Illustrative images from a high-speed video are shown in Fig. 1. lb.
Figure 1.1 Water jet utilisation in nature
(a) Toxotes jacularix providing train a of water slugs (photograph: David Stone)
(b) Snapping shrimp producing high-speed a water jet (photographs: Faculty of Appl. Physics, University of
Twente)
noitcudortnI 3
The purposeful use of waterjets is as old as human engineering. Reviews about
early cases of water jet utilisation for material removal, namely for soil removal and
hydraulic mining, are provided by ]eremic (1981), Summers (1995) and Wilson
(1912). Figure 1.2 shows a so-called hydromonitor as used in the 19th century on
mineral mining sites in the USA. In the 1920s, water jet were introduced into the
steel producing industry for descaling, and into the foundry industry for cleaning
castings. In those times the first systematic investigations into water jet formation
and material removal optimisation were performed especially in Germany (see
Rodehfiser, 1930).
erugiF 1.2 Early hydromonitor used for the removal of and soil kcor sirbed from mineral mining sites
:hpargotohp( HAB Weimar)
The first serious approach to use water jets for concrete hydrodemolition was
probably that of McCurrich and Browne (19 72). They found that water jet cutting
of concrete featured poor energy utilisation; estimated values varied between 400
and 4,000 G]/m .3 The pump pressure applied for this study was 70 MPa. The most
interesting results of the study were, from the point of view of engineering history,
the following:
)i( "The aggregate was impossible to cut at (an operating pressure )fo 70
MN/m2.";
(ii) '~ practicable site cutting tool will require pressures of at least 380
MN/m2. ''
Today is known that both statements were wrong. The research community at
that time did not know enough about material removal modes and the effects of
4 Hydrodemolition of surfaces concrete and decrofnier concrete structures
process parameters. However, the results were that discouraging that it took 10
more years till an industrial institution finally developed and introduced the first
commercial hydrodemolition unit. Modern hydrodemolition systems work at
operating pressures of about 100 MPa, thus, only about 30% of the threshold
suggested by McCurrich and Browne (1972). Since that, the technology was
rapidly growing. Already in the 1980s, about 10% of all contractors involved in
concrete rehabilitation in Austria, used water jets (Kloner, 1987). At present, this
tool is widely used for cleaning, profiling, removal, drilling and demolition of
concrete substrates and reinforced concrete structures (Momber, 1998a).
Hydrodemolition is state-of-the-art in concrete technology and structural rehabili-
tation. Major fields of application include the following:
(cid:12)9 bridge and parking deck repair;
(cid:12)9 construction joint cleaning;
(cid:12)9 decommissioning;
(cid:12)9 decontamination;
(cid:12)9 road maintenance;
(cid:12)9 tunnel rehabilitation.
The automatic, remotely controlled hydrodemolition robot shown in Fig. 1.3
probably best illustrates the high standard of the technique.
Figure 1.3 Modern Aquajet hydrodemolition (photograph: robot A.B., Holsbybrunn)
Introduction 5
1.2 Industrial applications
1.2.1 Civil and construction engineering
Water jet technology is a state-of-the-art technology not only in the area of surface
engineering. It is one of the most flexible techniques available in industrial
maintenance. In the industry, water jet technology is frequently used in the
following areas:
(cid:12)9 building sanitation and rehabilitation;
(cid:12)9 concrete removal and cleaning = HYDRODEMOLITION;
(cid:12)9 decontamination and demilitarisation;
(cid:12)9 demolition of technical structures;
(cid:12)9 foundation engineering;
(cid:12)9 industrial cleaning;
(cid:12)9 jet cutting of ceramics, fibre-reinforced plastics, food, glasses, metals and rocks;
(cid:12)9 maintenance of technical structures and equipment;
(cid:12)9 mechanical processing of minerals;
(cid:12)9 medical applications;
(cid:12)9 mining and rock cutting;
(cid:12)9 paint and lacquer stripping;
(cid:12)9 rock fragmentation;
(cid:12)9 sewer channel and pipe cleaning;
(cid:12)9 surface preparation for protective coatings.
Several of these applications as well as the corresponding major operational
parameters are summarised in Fig. 1.4.
Water jetting is state-of-the-art in civil engineering. A recent review, including
an extensive database, is given by Momber (1998a). Several aspects of civil
engineering use are also mentioned by Summers (1995). The applications include
the following:
(cid:12)9 cleaning of concrete joints prior to concreting (Utsumi et al., 1999);
(cid:12)9 cleaning of concrete, stone, masonry and brick surfaces (Lee et al., 1999);
(cid:12)9 cleaning of soils (Sondermann, 1998);
(cid:12)9 cutting of soil (Atmatzidis and Ferrin, 1983);
(cid:12)9 cutting and drilling of natural rocks in quarries (Ciccu and Bortolussi,
1998);
(cid:12)9 decontamination of industrial floors;
(cid:12)9 jet cutting of construction materials, such as tiles, natural rocks and glass
(Momber and Kovacevic, 1998);
(cid:12)9 preparation of soil samples (Hennies et al., 2002);
(cid:12)9 removal of asphalt and bitumen from traffic constructions (Momber, 1993);
(cid:12)9 removal of rubber deposits from airport runways (Choo and Teck, 1990a,b);
(cid:12)9 removal of traffic marks from roadways;
(cid:12)9 selective concrete removal by hydrodemolition (Hilmersson 1998; Momber,
1998b; Momber, 2003b; Momber et al., 1995);