Based on the two articles attached to the question. Please write a research paper about concrete explaining: what is concrete? definition of concrete and its properties. You’re free to use any new source when needed. The paper must Include the following:- Abstract:- Introduction: Introduce the materials that make up concrete, and the methods by which it deteriorates (physical, chemical, etc.)- body: 1. Ways to prevent physical deterioration2. Ways to prevent chemical deterioration3. Ways to prevent other deterioration4. Cost of each prevention type- Conclusion: Which methods of deterioration-prevention are best out of each type (look at cost, effectiveness, etc.)?(Add more questions to answer)- Reference:ACI MATERIALS JOURNAL
TECHNICAL PAPER
Title No. 115-M62
Mitigating Alkali-Silica Reaction and Freezing and Thawing
in Concrete Pavement by Silane Treatment
by R. A. Deschenes Jr., E. R. Giannini, Thano Drimalas, B. Fournier, and W. M. Hale
Alkali-silica reaction (ASR) and freezing and thawing (F/T) cause
premature deterioration and reduce the service life of concrete
structures, and both are difficult to mitigate in existing concrete
pavements once deterioration occurs. The objective of this research
program was to evaluate the efficacy of silane surface treatments
used to reduce the moisture state of concrete pavements, thereby
reducing further deterioration from ASR and F/T and increasing
the remaining useful life of the pavement. The pavement test section
evaluated contained a borderline-reactive fine aggregate and
marginal air entrainment. The efficacy of silane was evaluated by
instrumenting a pavement test section with devices for monitoring
strain and internal RH. Core samples were extracted before and
after treatment. The core samples were evaluated using the damage
rating index (DRI). Results indicate silane may reduce the rate
of deterioration in the concrete pavement compared to untreated
control sections.
Keywords: alkali-silica reaction (ASR); concrete pavements; freezing and
thawing (F/T); mitigation; silane.
INTRODUCTION
Concrete pavements containing borderline reactive
aggregates and marginal air entrainment may deteriorate
rapidly due to coupled alkali-silica reaction (ASR) and
freezing-and-thawing (F/T) deterioration.1 ASR formation
and expansion occur when reactive siliceous phases, within
some aggregates, dissolve in the presence of hydroxyl ions
in the cement pore solution.2,3 The dissolved silica forms
a gel product that imbibes pore solution from the cement
paste, and then expands. The expansive reaction may lead
to microcracks that develop over time, forming a network
that extends from one reactive aggregate particle to another
through the cement paste. The internal expansive forces
can lead to visible symptoms of deterioration, including
relative movements, map/oriented cracking (depending on
the extent of restraint and reinforcement detailing), deterioration at joints, and discoloration.4 This reaction will
continue until sufficient siliceous phases, alkalis, or water
are no longer available.2,3 The F/T deterioration mechanism
typically occurs due to viscous resistance to water transport
during freezing.5-7 The pressure causes expansion, spalling,
and cracking in the cement paste, which leads to microcracking and deterioration of mechanical properties.5-7 Deterioration can be prevented by entraining the concrete with
a well-dispersed network of air voids.5 However, deterioration can still occur if the concrete is critically saturated or
the air void network is disrupted. Deterioration will occur
under repeated exposure to F/T until the pressure is relieved
by cracking or the moisture state of the concrete is reduced
below the critical saturation threshold.5
ACI Materials Journal/September 2018
The coupled interaction of ASR and F/T was documented
by Bérubé et al.8 and modeled by Gong et al.1 The formation of ASR within concrete pores increases the resistance to
water transport and the degree of saturation of the concrete,
which reduces F/T resistance.1 When both deterioration
mechanisms occur in concrete, deterioration is exacerbated, leading to more expansion and deterioration than
would occur due to ASR or F/T alone.1,8,9 As deterioration
continues, cracks at the exposed surface of the concrete
provide an avenue for water to enter the concrete, increasing
the saturation state and leading to accelerated deterioration.
Reducing the available moisture within concrete may be
a viable means to limit both ASR and F/T deterioration.3
Stark10 and others observed that a threshold of 80% RH
(70 to 75°F [21 to 24°C]) is required to sustain the ASR
expansion mechanism.10-16 Powers5 observed that a critical
degree of saturation is necessary before F/T deterioration
occurs in concrete. It is difficult to quantify the threshold RH
necessary for F/T deterioration to occur because the relationship between internal RH and degree of saturation is dependent on the microscopic properties and hydration state of the
concrete.2,6-8,17,18 However, internal RH can be used to quantify changes in the moisture state imparted by treatment and
correlated to expansion and deterioration in the concrete.16
One means of limiting the ingress of rain or runoff is through
treating the concrete with a hydrophobic, vapor-transmissive
coating such as silane. Silane may allow sufficient drying
to mitigate deterioration for thin elements (less than 12 in.
[300 mm]) with large surface-area-to-volume ratios.19 Silane
surface treatments penetrate the concrete surface and form a
hydrophobic silicone resin network.20 Modern silane products consist of water-based alkylalkoxysilane, solvent-based
alkyltrialkoxysilane, or non-solvent-based isobutylalkoxysilane silane compounds.17,20,21 Silanes have been used to
mitigate ASR by drying concrete elements, such as columns
and barrier walls.11,13,14 The same technique may be effective
for mitigating combined ASR- and F/T-related deterioration
in concrete pavements, potentially extending the service
life of concrete structures.11,18 ASR and F/T may prove
more difficult to mitigate in pavements because drying only
occurs through the exposed surface, while subgrade moisture may replenish water. Stark et al.10 reported silane to be
ineffective for pavements because a measurable reduction in
ACI Materials Journal, V. 115, No. 5, September 2018.
MS No. M-2017-298.R1, doi: 10.14359/51702345, was received September 5,
2017, and reviewed under Institute publication policies. Copyright © 2018, American
Concrete Institute. All rights reserved, including the making of copies unless
permission is obtained from the copyright proprietors. Pertinent discussion including
author’s closure, if any, will be published ten months from this journal’s date if the
discussion is received within four months of the paper’s print publication.
685
RH was not observed within 1 year of monitoring. Silane
was again evaluated in 2011 as part of the FHWA’s ASR
Development and Deployment Program.15 Silane was applied
to a test section of the Interstate 530 pavement in Pine Bluff,
AR. Strain and internal RH were monitored periodically for
1 year before the research program ended.15 Deterioration
in the pavement increased rapidly, and rehabilitation was
required before sufficient results could be gathered. The
project results were inconclusive and the long-term efficacy
of silane applied to concrete pavements remains unknown.
An additional concern with silanes applied to concrete pavements is reduced efficacy over time due to ultraviolet radiation and traffic wear. Silanes typically penetrate the concrete
sufficiently and reapplication after 5 years may be sufficient;
however, more than 3 years of monitoring would be required
to validate this for concrete pavements.8,11
Measuring the efficacy of silane treatments applied to
pavements requires a combination of internal RH monitoring, strain (expansion), and internal deterioration monitoring. Bérubé et al.11 and others15,22,23 measured internal RH
in concrete using commercial RH probes inserted into holes
drilled into the concrete surface. Strain is the most readily
quantifiable symptom of ASR, and perhaps F/T, but can only
be measured at the surface.21,24 The Damage Rating Index
(DRI) is a semi-quantitative index of deterioration present
within concrete, and provides an assessment of deterioration occurring throughout the cross section of the concrete
element investigated. This includes internal deterioration
caused by out-of-plane expansions that cannot be measured
using surface strain or cracking index methods. The DRI
method can also be used to differentiate between ASR and
F/T deterioration.25 The DRI, therefore, provides greater
insight into the cause and extent of internal deterioration that
occurred throughout the life of the concrete.25-33
Previous research programs have investigated topical
treatments with lithium or silane to mitigate ASR or F/T in
concrete pavements. However, these programs were shortterm (1-year) monitoring of pavement performance and
focused on one deterioration mechanism.10,15,19 Lithium
treatments proved largely ineffective due to limited penetration into the concrete substrate, and sufficient monitoring
was not conducted to determine the efficacy of silanes.15,19
The objective of this research is to establish the efficacy of
silane treatments applied to concrete pavements deteriorating from a combination of ASR and F/T. The Interstate
49 pavement in Northwest Arkansas was instrumented for
monitoring strain and internal RH in January 2014, treated
in March 2014, and monitored until October 2016. Core
samples were collected before treatment as an initial assessment of deterioration, and 2 years after treatment to assess
differences in deterioration imparted by the treatment.
RESEARCH SIGNIFICANCE
This paper presents the longest-running study on the efficacy of silanes applied to pavements, and includes 3 years
of strain, internal RH, and DRI results. Silane was investigated as a possible means of slowing combined ASR and F/T
related deterioration in concrete pavements. Although the rate
of deterioration measured in the pavement was limited, the
686
Table 1—Job-approved concrete mixture design
Material
lb/yd3 kg/m3
Information
Cement
451
224
Type I
Fly ash
113
56
Class C, 20% replacement by mass
Air
—
—
6 ± 2% specified (air entrainment)
Water
214
106
—
Coarse aggregate
2051
1217
Limestone, 1.5 in. (38 mm)
Fine aggregate
1082
537
River sand
w/cm
0.47
Slump
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