Is Mortar Good For Concrete Repair
Mortars and grouts
Peter A. Claisse , in Civil Engineering Materials, 2022
28.5 Cementitious repair mortars
The most common application for repair mortars is the repair of spalling caused past reinforcement corrosion in concrete structures with chloride ingress. This is a major manufacture with large repair contracts in progress worldwide. Proprietary products containing cements, cement replacements, and plasticisers, and shrinkage compensating admixtures are supplied preblended.
Figure 28.seven shows a typical repair particular and Figs. 28.8–28.11 bear witness a typical repair sequence on a critical structure. Great care must be taken to remove all the chloride contaminated and spalling physical, particularly backside the bar. The reinforcing bar is so shotblasted clean, and inspected to ensure that the loss of section due to corrosion is not critical for the structure. The grout is then poured in every bit shown or, alternatively, it may be pumped in at the lesser of the repair. The grout must take a similar coefficient of thermal expansion to the parent concrete to avert debonding during hot or cold weather, so cementitious grouts are mostly preferred to epoxies (encounter Section 35.6.3). A problem with patch repairs is that the new grout volition promote the formation of a strong cathode, and this may lead to "incipient anodes" at the edges of the repair causing rapid corrosion. Cathodic protection may be necessary to stop this (meet Chapter 31). Skillful curing is essential for repairs; air curing is seldom acceptable.
Figure 28.7. Typical Arrangement for Repair Mortar
Effigy 28.eight. Repair Sequence 1
Jacks are positioned to deport the load during the repair.
Figure 28.9. Repair Sequence 2
Chloride contaminated physical is removed by hydrodemolition and the reinforcing bars are cleaned.
Figure 28.10. Repair Sequence iii
The shutter has been placed and the grout is being poured into it.
Figure 28.11. Repair Sequence four
A completed repair.
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Calcium Aluminate Cements
Jason H. Ideker , ... Bruno Touzo , in Lea'southward Chemical science of Cement and Physical (Fifth Edition), 2022
12.5.one Building Chemistry
The term 'Building Chemistry' is oftentimes used by the dry-mix mortar industry referring to finishing or repair mortars. The use of calcium aluminates in these applications has grown continuously during the last 30 years corresponding to a demand of increased productivity and aesthetic considerations. In most of these applications, combined systems containing CAC, with calcium sulfate and or PC (every bit described in Section 12.4.3) and the calcium aluminates cements are a precursor to ettringite germination. Early ettringite formation gives rapid setting or hardening, rapid reduction of internal humidity (drying) and shrinkage compensation.
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Alkali activated repair mortars based on different precursors
Vilma Ducman , ... Aljoša Šajna , in Eco-Efficient Repair and Rehabilitation of Concrete Infrastructures, 2022
11.5 Hereafter trends
Then far, many researchers succeeded in obtaining AAM with good workability and high compressive strength, which are the prerequisite for because the potential of such material to be used equally repair mortars for concrete. Merely, as can exist seen from literature, every bit well as from our own experience, there is still room for progress in the evolution of repair mortar.
The most researched system is that with metakaolin as the forerunner textile. For this system, in that location are also reports about its successful utilise equally repair mortar in real weather (Zhang et al., 2022a,b). Attempts have also been made with many other (waste) materials and their combinations to be used as repair mortars, but mostly at a laboratory level. For such precursors, there is still no definite answer as to which activators are the most adequate and what their ratio to the precursors should be in gild to develop repair mortars that would meet all the criteria prescribed in the standard for concrete repair mortars. It seems that, due to the complexity of the systems, the most mutual arroyo is however that of trial and error, which tin be time consuming and usually does not give complete insight into the mechanisms of bonding.
Furthermore, there are some other open issues. Amid them, the urgent one is the evolution of commercially available superplasticizers for such brine-activated systems. These systems certainly need effective superplasticizers that volition brand structure denser. It is oft reported (Natali et al., 2022; Zhang et al., 2022a,b) through determination of h2o absorption, capillary uptake, and/or mercury intrusion porosimetry (MIP), that such systems are rather open on a microstructural level, in comparison to cement-based mortars, and consequently decumbent to the ingress of different chemicals. Chloride, sulfate, and water tin easily penetrate the structure, which tin can crusade different types of deterioration.
Having a denser structure might besides hinder the problem with efflorescence, which is also one of the major bug when using alkali-activated repair mortars. Some successful attempts accept been made to decrease efflorescence by application of potassium activators instead of sodium ones, or by adding calcium aluminate admixture, which reduces the mobility of alkalis, or even by application of hydrothermal curing (Pacheco-Torgal et al., 2022a). As obviously from contempo research, some of the shortcomings might be overcome by the application of hybrid systems (Garcia-Lodeiro et al., 2022).
The last, merely not the least important, factor that needs farther investigation is the adherence of alkali-activated mortars to different substrates. In some publications (Vasconcelos et al., 2022) it is reported that the adherence of brine-activated mortars to the cement-based substrate is poor. The influential parameters are chemical bonding between AAM layer and substrate, shrinkage/expansion matching, and too mechanical interlocking (commonly improved if the surface is crude).
For marketplace penetration and technical acceptance, some more than successful demonstrated cases (not only laboratory ones) which will requite certainty virtually compatibility, durability, and long service life, will be of the utmost importance.
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Microscopic examination of deteriorated physical
T.K. Nijland , J.A. Larbi , in Non-Destructive Evaluation of Reinforced Concrete Structures: Deterioration Processes and Standard Test Methods, 2022
8.5 Evaluation of repairs
Physical petrography may also be used to evaluate rehabilitation strategies, repairs and repair methods, past assessing the depth at which sound concrete starts. Effigy viii.26 illustrates a case where a polymeric repair mortar was applied on fire-damaged physical that was non brought back to the non-cracked substrate. It may also exist used to assess the adhesion between different layers and materials ( Fig. viii.27), such as repair mortars, gunnite or coatings. Microscopic investigation may also be used to appraise the long term outcome of electrochemical methods such as cathodic protection. The long-term result of inevitable acid product at the anode may be visible in an increase of capillary porosity of the cement paste around the anode (Polder et al. 2002).
viii.26. Microphotograph showing a polymeric repair mortar practical on burn-damaged concrete, that was not brought back to the not-cracked substrate (aeroplane polarized light, view v.four mm × three.5 mm).
8.27. Microphotograph with example of successive surface finishes on concrete and surface parallel cracking in the underlying concrete (plane polarized light, view v.4 mm × 3.5 mm).one
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Geopolymeric repair mortars based on a low reactive clay
Walid Tahri , ... Samir Baklouti , in Eco-Efficient Repair and Rehabilitation of Concrete Infrastructures, 2022
12.1 Introduction
Worldwide infrastructure rehabilitation costs are staggering. The patch repair method is widely used to restore the original weather condition of the concrete structures (Emmons and Vaysburd, 1994, 1996 ). About patch repair mortars fall into two categories: mortars based on organic binders (epoxy resin or polyester) or those based on inorganic binders, similar Portland cement (PC). The former are associated with toxic side furnishings ( Pacheco-Torgal et al., 2022b) while the latter are known for their loftier embodied carbon (Pacheco-Torgal et al., 2022). Geopolymers are novel inorganic binders with a high potential to replace PC-based ones (van Deventer et al., 2022). The geopolymerization of alumino-silicate materials is a complex chemical process involving the dissolution of raw materials, transportation or orientation, and polycondensation of the reaction products (Li et al., 2022; Van Deventer et al., 2022; Provis, 2022; Pacheco-Torgal et al., 2022). Investigations in the field of geopolymers reveal a third category of mortars with potential to be used in the field of concrete patch repair (Pacheco-Torgal et al., 2022a). Some authors (Pacheco-Torgal et al., 2008a) have shown that concrete specimens repaired with geopolymeric mortar and one day curing accept higher bail strength than specimens repaired with electric current commercial repair products after 28 days curing. This is a promising operation because adhesion to the concrete substrate is a crucial property of the repair mortars (Khan et al., 2022). This chapter presents results of an investigation concerning the development of geopolymeric repair mortars based on a low reactive, calcined dirt. The influence of replacing minor amounts of calcined clay with fly ash (FA) and metakaolin (MK) was also studied.
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Performance of brine-activated mortars for the repair and strengthening of OPC physical
F. Pacheco-Torgal , ... S. Baklouti , in Handbook of Alkali-Activated Cements, Mortars and Concretes, 2022
23.2 Concrete patch repair
The patch repair method is widely used to restore the original weather condition of concrete structures (Emmons and Vaysburd, 1994, 1996). In gild to ensure the structural compatibility, Morgan (1996) states that repair mortar must meet the requirements divers in Tabular array 23.ane.
Table 23.1. Structural compatibility – general requirements for repair mortars
| Properties | Relation between the repair mortar (Rp) and the concrete substrate (Cs) |
|---|---|
| Forcefulness in compression, tension and flexure | Rp ≥ Cs |
| Modulus in compression, tension and flexure | Rp ~ Cs |
| Poisson'southward ratio | Dependent on modulus and type of repair |
| Coefficient of thermal expansion | Rp ~ Cs |
| Adhesion in tension and in shear | Rp ≥ Cs |
| Curing and long-term shrinkage | Rp ≥ Cs |
| Strain capacity | Rp ≥ Cs |
| Pitter-patter | Dependent on whether creep causes desirable or undesirable effects |
| Fatigue functioning | Rp ≥ Cs |
Source: Morgan, 1996, Copyright © 1996, with permission from Elsevier.
Figure 23.1 shows the disadvantages related to the apply of composite materials with different modulus of elasticity. Still according to Morgan (1996), the repair mortars must comply with several requirements in club to ensure the compatibility with the concrete substrate (Figure 23.2).
Effigy 23.1. Mechanical behaviour of materials with dissimilar modulus of elasticity: (a) load perpendicular to the interface; (b) load parallel to the interface.
Figure 23.2. Factors that influence the immovability of repair mortars.
(reprinted from Morgan, 1996, Copyright © 1996, with permission from Elsevier)Several modes of repair failure were recently reported past Kristiawan (2012). The primary modes of repair failure were cracking (32%), debonding (25%), connected corrosion of embedded reinforcement (22%), brine amass reaction (iv%) and others (17%). Concerning cracking, which is the most important repair failure in most cases it could be due to restrained shrinkage (Pattnaik and Rangaraju, 2007). Figure 23.3 shows the cracking behaviour of repair mortars due to differential shrinkage betwixt the reparation layer and the substrate concrete, which is a very heterogeneous and complex process.
Figure 23.3. Development of neat in a concrete reparation.
(reprinted from Sciumé et al., 2022, Copyright © 2022, with permission from Elsevier)ASTM C928 (2004) recommends that air shrinkage performance should non exceed 0.15% of the initial length. Nonetheless, since dandy is also affected past creep and elastic modulus, a unmarried shrinkage magnitude approach like the one previously mentioned in Table 23.1 is insufficient to prevent it. According to Kristiawan (2012) the about suitable way of reproducing the restraint of the patch repair system is past using the ring test. The ring test is normally used to assess restrained shrinkage (Khan, 2022) and provides a useful qualitative comparison of the cracking performance of repair mortars (Beushausen and Chilwesa, 2022). This test is standardized past ASTM C1581 (2007) and its awarding encompasses the cess of the time to start great, the number and the width of cracks. More than information on the ring exam tin can be plant in the piece of work by Hossain and Weiss (2006) who study restrained ring specimens tested using different geometries and boundary weather.Mirza et al. (2014) analysed 40 unlike physical repair mortars (15 cement-based, 11 polymer-modified cement-based, 14 epoxy-based) stating that freezing–heating cycle durability exam is of paramount importance for the selection of the nearly suitable repair materials in severe climatic weather, which means that thermal compatibility with the base concrete is also a very important parameter concerning the pick of repair mortars.
Rapid adhesion to the physical substrate is a fundamental holding of patch repair mortars, allowing the structure back into service. The adhesion in repair systems is a complex phenomenon resulting from a synergic effect of the surface roughness of concrete substrate, the presence of microcracks in the most-surface layer and deteriorated grains of amass as well as processing properties of repair materials, including interfacial tension between the bond coat and/or repair materials (Garbacz et al., 2005). The application of the patch repair mortar is therefore preceded by cleaning (with a wire brush) the concrete surface to remove pieces of degraded physical. Moreover, every bit the roughness of the concrete substrate affects the performance of near patch repair mortars, information technology becomes necessary to artificially increase its roughness (about of the time using sand-blasting), regardless of the cleaning performance.
Most patch repair mortars autumn into two categories, the mortars based on organic binders (epoxy resin or polyester) and those based on inorganic binders like Portland cement, which are available commercially as a pre-pack mixture of Portland cement, aggregates, silica smoke, fibres and other additives. Cement-based repair mortars evidence improved adhesion when the surface of the concrete substrate was previously wetted. Withal, epoxy-based repair mortars evidence poor adhesion in moist surfaces. Murray (2009) mentioned that latex-modified patch repair mortars are used widely and successfully. Nonetheless, the latter are more than cost effective and less toxic. Co-ordinate to Pacheco-Torgal et al. (2012) the toxicity of building materials is a crucial issue nether the recently canonical Regulation (EU) 305/2011 related to the Structure Products Regulation (CPR) which has been in effect since 1 July 2022.
Recent investigations in the field of alkali-activated binders reveal a 3rd category of mortars with high potential to be used in the field of concrete patch repair (Pacheco-Torgal et al., 2007, 2008). Since the adhesion to the concrete substrate is a crucial property of the repair mortars, some results related to the comparison between alkali-activated mortars and commercial products for the repair of concrete structures are presented. The adhesion strength was evaluated using the slant shear examination. The slant shear exam uses foursquare prisms made of two halves, one of the concrete substrate and one of the repair cloth, tested under axial compression. The adopted geometry for the camber shear specimens was a 50 × 50 × 125 mm3 prism with an interface line at 30° to the vertical. Bond force was calculated by dividing the maximum load at failure by the bail surface area and was obtained from an boilerplate of four specimens adamant at the ages of 1, 3, 7 and 28 days of curing. In social club to increment the specific surface of the concrete substrate an etching procedure was carried out. The concrete surface was immersed in a 5% hydrochloric acid solution for five min and then carefully washed to ensure the removal of CaCl2 which results from the reaction betwixt HCl and Ca(OH)ii. The specimens were named later on the repair materials and physical substrate surface treatments. Specimens using concrete substrate repaired with commercial product R1 with and with no surface treatment were named respectively, R1-ES (etched surface) and R1-NTS (no treatment surface). Similarly, when the brine-activated based binder was used to bond the 2 halves they were named GP-ES and GP-NTS, respectively. Slant specimens with substrate surface treatment as cast confronting metallic formwork, and as cast against forest formwork were also used with alkali-activated binder and were named GP-MF and GP-WF, respectively. The results of the upshot of the several repair solutions on average adhesion strength are shown in Figure 23.4.
Effigy 23.4. Adhesion strength using the 'camber-shear' test.
(reprinted from Pacheco-Torgal et al., 2008, Copyright © 2008, with permission from Elsevier)It can exist seen that the specimens repaired with the brine-activated mortar present high adhesion strengths even at early ages. Specimens repaired with alkali-activated mortar with 1 day curing accept college bond strength than specimens repaired with current commercial products after 28 days curing. Specimens repaired with the alkali-activated mortar appear to be influenced non past the chemical handling in sawn concrete surface substrates, only past the use of physical surfaces as cast confronting formwork. Those kinds of surfaces are rich in calcium hydroxide simply lack exposed coarse aggregates which could contribute to improve bail strength due to silica dissolution from the aggregate surface. The strength performance of commercial repair products is very dependent on curing time and this constitutes a serious setback when early bail force is required. The results testify that bond force using repair product R2 is conspicuously influenced past the surface treatment. Even if the current commercial repair materials had the same mechanical performance as the alkali-activated binder, the cost of the cheapest i (R1) is nevertheless 6.9 times college than the brine-activated binder.
When comparison the price to bond strength ratio, the differences are even higher, with the cost of the cheapest solution with current commercial repair products (R1-ES) being 13.8 times higher than the alkali-activated repair mortar (see Figure 23.5). All the same the assessment of the overall functioning of the new mortars concerning structural compatibility and durability is yet to be fully investigated.
Effigy 23.v. Cost-to-forcefulness ratio later on 28 days curing according to repair solution.
(reprinted from Pacheco-Torgal et al., 2008, Copyright © 2008, with permission from Elsevier)Other authors (Tahri et al., 2022) studied the development of alkali-activated repair mortars based on calcined Tunisian clays, reporting a very depression modulus of elasticity and an excessive unrestrained shrinkage. Further studies (Tahri et al.,2014) prove that an adequate unrestrained shrinkage can be obtained (Figure 23.6) when calcined Tunisian clays are partially replaced by fly ash or metakaolin and near importantly when the alkali-activator/binder mass ratio is reduced to 80% of the initial ratio.
Effigy 23.6. Unrestrained shrinkage equally a office of curing time (Tahri et al., 2022).
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Bonded concrete overlays for repairing physical structures
J.L. Silfwerbrand , in Failure, Distress and Repair of Concrete Structures, 2009
Other overlay properties
Overlay permeability may influence bond durability, for example, very impermeable overlays effect in stresses at the interface when wet from the substrate cannot drift through the overlay (Schrader et al. , 1992). The addition of polymers to cementitious repair mortars was plant to upshot in better bail characteristics on specimens subjected to extensive temperature cycles (Atzeni et al., 1993). Chen et al. (1995) measured a pregnant increase in shear bail force with the improver of short carbon fibres to repair mortar. They attributed the effect to the decrease in drying shrinkage and the resulting decrease in interface stress. Granju (1996) states that fibres heighten bond durability through the control of crack development.
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Mortar, plaster, and render
Jeremy P. Ingham BSc (Hons), MSc, DipRMS, CEng, MInstNDT, EurGeol, CGeol, CSci, FGS, FRGS, MIAQP , in Geomaterials Under the Microscope, 2022
EXAMPLES OF SPECIALIST MORTARS
The examples below are not intended to exist a comprehensive review of mortars for specialist applications. Instead, selected materials accept been used to illustrate the range of ingredients that are likely to be encountered in specialist mortars.
Figures 326 and 327 testify a proprietary repair mortar for concrete. It consists of fine (1.18 mm nominal maximum sized) quartz fine amass bound by Portland cement with polymer modification, a PFA mineral improver, calcite dust filler, and polypropylene microfibres. Figures 328 and 329 show a proprietary mortar designed for setting fastenings in concrete. It consists of 600 μm nominal maximum sized, quartz fine aggregate jump by epoxy resin and Portland cement.
326. Proprietary repair mortar for concrete, showing fine aggregate particles (white) and cement matrix (night brown) with PFA (white spheres); PPT, ×150, 1mm across.
327. A cluster of polypropylene fibres (brightly coloured) within a proprietary repair mortar for physical repair; XPT, ×150, 1mm across.
328. Proprietary mortar for setting fastenings, exhibiting abundant unhydrated Portland cement grains enclosed by epoxy resin. Fine aggregate particles are shown white; PPT, ×150, 1mm across.
329. Same view as 328 in cross-polarized light. The epoxy resin in the matrix is isotropic (black), the unhydrated cement grains announced bright, and quartz fine aggregate particles are shown white/grey; XPT, ×150, 1mm across.
Figure 330 shows a proprietary grey-coloured cementitious tile adhesive. It consists of quartz sand fine amass, bound by Portland cement with a calcite dust filler and latex bonding amanuensis. Figures 331 and 332 testify a brown-coloured cementitious tile agglutinative, comprising a mixture of Portland cement and calcium aluminate cement, with calcite filler and quartz fine amass. Figures 333 and 334 show a proprietary white-coloured tile adhesive, comprising polymer modified white Portland cement, with calcite filler and quartz fine aggregate. The adhesive is designed to exist very fast setting and it includes a latex condiment. Figures 335 and 336 testify a flexible floor tile adhesive, apparently comprising particles of rubber and calcite dust filler, leap by a matrix of resin and Portland cement.
330. Proprietary gray-coloured cementitious tile agglutinative, showing uncarbonated Portland cement binder (chocolate-brown) with particles of calcite dust filler (light brownish). An unhydrated cement grain is seen middle right; XPT, ×300, 0.5mm across.
331. Chocolate-brown-coloured Portland cement and calcium aluminate cement tile adhesive. Unhydrated/partially hydrated calcium aluminate cement particles are frequently seen (black/red) and an unhydrated Portland cement grain is seen in the centre of view. Quartz fine aggregate is shown white; PPT, ×300, 0.5mm across.
332. Same view as 331 in cross-polarized calorie-free. Uncarbonated cement matrix appears dark brown and particles of calcite dust filler appear low-cal brown. Quartz fine aggregate particles are shown white; XPT, ×300, 0.5mm across.
333. Proprietary white tile adhesive. The cement matrix appears brown and includes a frequent abundance of unhydrated/partially hydrated white Portland cement grains. Fine amass particles are shown white; PPT, ×150, 1mm across.
334. Aforementioned view as 333 in cross-polarized light. The uncarbonated polymer modified cement matrix is isotropic (black) and small particles of calcite filler are now clearly seen (light brown). The brightly coloured 'blocky' particle in the middle right is anhydrite; XPT, ×150, 1mm beyond.
335. Flexible floor tile adhesive with particles of safety (blackness) and calcite dust filler bound by a matrix of resin and Portland cement. Air voids announced yellow and an unhydrated cement grain is seen in the centre of view; PPT, ×150, 1mm beyond.
336. Same view equally 335 in cross-polarized calorie-free. The resin/Portland cement matrix is isotropic (black) and calcite filler particles appear vivid; XPT, ×150, 1mm across.
Figure 337 shows a mortar used equally 'stone filler'. A mixture of calcite dust and white Portland cement has been used to fill voids sympathetically that occur naturally in travertine floor tiles.
337. 'Stone filler' mortar (dark-brown) filling a void on the top surface of a natural stone (travertine) floor tile; XPT, ×25, 5mm across.
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Maintenance of aged land-based structures
A VAN GRIEKEN , in Condition Assessment of Aged Structures, 2008
16.5.6 Restoration of concrete
There are a range of repair methods for defective concrete including, among others, the following:
- •
-
Conventional patch repairs involve the procedure of breakout, surface grooming of the concrete including the application of a bail glaze, surface preparation of any exposed reinforcement through the application of a protective coat or bail coat, application of a repair mortar which is compacted and cured, and possibly the awarding of a finishing coat. The removal of lacking concrete is destructive, dusty, expensive and tiresome using pneumatic equipment. A more effective means is the use of hydro sabotage equipment which is less noisy, involves less dust, and is faster than conventional means. The high-pressure h2o lance readily cuts through the concrete and tin fifty-fifty cut reinforcing bars. It produces a crude make clean base surface which is ready for the awarding of the repair mortar. Furthermore it causes minimal damage to the base physical in terms of micro-cracking. Hydro demolition robots are now being used on projects of significant size and are able to apace remove large volumes of concrete in controlled areas.
- •
-
Big surface repairs demand the utilize of a suitable mortar which has very low shrinkage characteristics to avoid delamination. Where the restoration of the exposed area involves relatively large volumes, poured micro concrete may be a more suitable solution than the application of a proprietary and hand-placed mortar. Every bit an alternative, sprayed mortar produces dense concrete and is suitable for a variety of applications.
- •
-
Structural repairs require advisedly staged breakout and reapplication to ensure that the element has acceptable structural capacity for the applied loads which are relevant during the works. Structural repairs differ from other repairs in that the structural capacity of the chemical element needs to exist restored to that of the original undamaged element or to a designed structural capacity. Thus the repair mortar in compression zones and columns needs to blot compressive forces. This requires that the repair mortar is in full contact with the base concrete and does not shrink from the interfaces and that the repair mortar has adequate compressive capacity to take up the load. However, inquiry is ongoing regarding the load path through or around structural repairs.
There are a number of repair mortars for patch repairs or larger restoration repairs:
- •
-
Ordinary Portland cement concrete is suitable for large volumes and non-aggressive exposure weather. Nonetheless, the concrete needs to take operation characteristics which are compatible with the base concrete. The placement sequence, vibration/compaction and curing demand experienced contractors.
- •
-
Polymer modified cement mortars are now widely used and include a variety of polymers. These mortars are generally dumbo and take low carbon dioxide infusion backdrop and loftier chloride ingress/protection characteristics. The latest mortars take been designed to minimise linear shrinkage to around 500 micro strain. Withal it is important to ensure that this highly alkali metal material does not create insipient anodes at the boundaries particularly in the example of chloride contaminated and wet structures.
- •
-
The fine aggregates in micro concrete produce a concrete which is suitable for heavily reinforced big repairs and for pouring into formed-up sections.
- •
-
Calcium aluminate cements (Scrivener, 2005) are special cements which:
- –
-
harden rapidly
- –
-
have high abrasion resistance
- –
-
have high resistance to microbial acrid attacks.
These have been produced for more than than 100 years but are plush, and have been used for, amongst others, dam spillways and sewerage structures.
- •
-
Special combinations are being trialled for special conditions such as in the Persian Gulf area where the add-on of styrene butadiene latex (SBR) and silica fume resulted in increased durability and reduced crack formation and decreased chloride ingress rates.
- •
-
Research is being carried out into the feasibility of total or fractional replacement of conventional polymer dispersions which are largely derived from petrochemicals, with renewable raw materials such equally sugar-based dispersions and substituting conventional aggregates with waste fillers.
Table 16.five provides a summary of restoration options.
Table 16.5. Restoration options
| Method | Method/textile/awarding | Unsuitable applications |
|---|---|---|
| Patch repair– polymer modified concrete | Polymer modified mortar suitable for most cases |
|
| Patch repair – cementitious |
|
|
| Reconstruction |
|
|
| Shotcrete |
|
|
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Innovative ABC Techniques
Mohiuddin Ali Khan Ph.D., M.Phil., DIC, P.E. , in Accelerated Bridge Construction, 2022
iv.three.iii Use of new concrete materials
Over the years, concrete mixtures are using admixtures with Portland cement pulverization as the binding agent of aggregates. Mod physical technology has led to the following types of special concrete materials:
- •
-
Smart concrete
- •
-
Accelerators
- •
-
Air-entraining admixtures
- •
-
H2o reducers
- •
-
Super plasticizers
- •
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Pozzolans
- •
-
Emulsions
- •
-
Antiwashout admixture for underwater concrete
- •
-
Spliced girders of varying depth: Enables lightweight concrete to attain spans of over 200 ft.
- •
-
Self-consolidating physical (SCC): Because vibration time is saved, SCC helps ABC; more workable concrete with lower permeability than conventional concretes.
- •
-
Rapid setting concrete: Nonshrink, multipurpose, high-strength repair mortar used for concrete repair, plaster repair, mortar bed, formed piece of work, vertical, and overhead applications.
- •
-
Blended cement concrete: A blend of Portland cement and a combination of silica smoke or fly ash used for enhanced forcefulness and durability. Used in loftier-operation applications with materials such every bit slag cement.
- •
-
Fibermesh concrete: Microsynthetic fibers forestall all early historic period cracks during concrete's plastic land.
- •
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FRP physical
- •
-
CFRP concrete: For repair and retrofit of concrete structures with glass or FRP.
- •
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GFRP concrete
- •
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Glass cullet and autoclaved aerated concrete
- •
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Concrete admixtures
- •
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Fly ash concrete
- •
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Pumice-Crete
- •
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Cement substitutes
- •
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HPC
- •
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UHPC ultra-HPFRC
- •
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Lightweight aggregate concrete
- •
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Recycled concrete aggregate (RCA) concrete
- •
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Accelerated cure bandage-in-identify concrete
- •
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EDC
- •
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Exodermic span deck
- •
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Reactive powder concrete (RPC) bridge girders
- •
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Total-depth precast concrete deck panels (FDDP)
- •
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Cementitious materials physical (fly ash, blast furnace slag, and silica fume)
- •
-
Deck overlays: Apply of silica fume, pozzolans, wing ash, and slag and high early on strength LMC
Trade names for these products include UHPFRC, RPC, Ductal, CoreTUFF, BSI, Densit, and Cemtec.
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