Abu Dhabi University College of Engineering and Computer Science SUM B
Surface deterioration of pavement's Interlocking-Block
Submitted to: Dr. Samer Al Martini. Submission Date: 13rd of Aug 2013 Submitted by: •
Abu zuhri Ahmed F A
1030006
•
Abdalrahman Al Attar
1000217
•
Rami Yousef Shehada
1011008
•
Mohamed elamin
1010053
Abstract The purpose of this research is to discuss brick surface deterioration and scaling Depending on clay and the manufacturing process, the finished appearance of clay brick can vary greatly. Repairing concrete is a worldwide multi-million dollar business. This type of cracking happens in freshly placed concrete due to rapid evaporation of humidity from the concrete surface and is commonly referred to as plastic-shrinkage cracking. This can occur at any time due to an unlikely combination of temperature, low humidity and wind. When the rate of evaporation is as high as 0.2 or 0.3 pounds per square foot per hour, protective measures must take. The Portland Cement Association and other agencies have considered this problem and propose the following provisions to reduce the possibility of plastic-shrinkage cracking. Erect windbreaks to reduce wind velocity over the concrete surface. Erect sunshades to reduce concrete surface temperature. Also, lower concrete temperature during hot weather by using cool aggregates and mixing water. Avoid heat the fresh concrete during cold weather. Care for the concrete with temporary wet covers during any considerable delay between placing and finishing. Reduce time between placing and start of curing. Protect the concrete during the first few hours after placing and finishing reducing evaporation.
CHAPTER 1: INTRODUCTION
Concrete interlocking pavers are individual precast concrete units. They are made on specially aimed paving stone machines according to ASTM or CSA standards. This specialized manufacturing process ensures an challenging quality controlled environment that produces pavers of higher strength and durability than normal concrete. Pavers are a minimum of 8000 psi, compared to about 2500 psi for poured in place concrete. The Roman armies used the original paving stone centuries ago. They built roads using an aggregate base with the assignment of stones on top. These roads are still in place today and wind their way through the European landscape. After World War II, there was a wonderful need for rebuilding. To help the construction of roads, the Dutch recreated stone cobbles in concrete. In the 60’s, Germany improved the rectangular “Holland Stone” by creating dentate shapes. In the early 70’s the popularity of paving stones reached the shores of North America and have gained in popularity ever since. Pavers are placed on a one-inch bed of sand over a compressed aggregate base. Interlocking concrete paving stones are used at airport, container faculties, railway container faculties, municipality streets, plazas, parks, driveways, walkways and patios. Pavers are the perfect solution for almost any applications because of their high quality, visual value, and lower life cycle cost in contrast to asphalt or concrete. Interlocking Concrete Pavers (ICPs) are not the same as bricks; bricks are made of clay and heated in kilns to harden. Interlocking pavers are a concrete product, produced with specialized tools and made to specific industry criteria.
CHAPTER 2: THEORETICAL BACKGROUND
Interlocking concrete pavers: The manufacturing process Quality mix = Quality pavers Defined scopes of any mixture used for concrete pavers will depend on locally available materials, manufacturing equipment requirements, and the desired final texture and quality of the paving unit. A low water-cement ratio (usually between 0.27 and 0.40) is used to produce a no slump concrete with high strength and durability. The concrete mix normally contains at least 16% Type I Portland cement based on dry weight. Nominal maximum aggregate size is generally 3⁄ 8 inch, with a common aggregate ratio of about 60% to 70% sand with the rest being gravel. The fineness modulus of the sand and gravel used varies from region to region. Product densities usually range from 135 pounds to 145 pounds per cubic foot. Admixtures are often used to increase concrete strength, reduce mold wear, and reduce efflorescence. Water-repelling admixtures such as calcium stearate may be added to reduce water absorption by the paver. Super plasticizers, added at the rate of about 0.4% of cement by weight, disperse cement grains, permitting water decreases that produce high early strengths. The extra fluidity gained by the use of super plasticizers also reduces the effort required to remove the paver s from the mold, thus reducing mold wear. Coloring pigments disperse more uniformly in super plasticized mixes, and machine feed times of the mixes are reduced during paver manufacture. Reductions in the total quantities of cement needed can be achieved
by partial replacement of a pozzolan such as fly ash. Besides reducing cost, pozzolans benefit control efflorescence. (Jr, 1996)
Influence of Construction Method on Water Permeation of Interlocking Block Masonry A technical note done by K. B. Anand and K. Ramamurthy (Ramamurthy, 2001), discusses water penetration resistance studies on a solid interlocking block masonry system, approving ASTM E 514-90 for the influence of the type of bedding (dry stacking, thin jointing, and mortar), surface finishes (stucco and plaster on one side or both sides), and simulated wind velocities (0, 50, and 100 km/h). Closes of the study based on the comparative performances of Silblock masonry and are appropriate for the range of parameters investigated, which estimated that: •
Silblock masonry without a surface finish is appropriate for rain-protected and interior walls.
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Outside face protection, by either stucco or plaster, reduces the leakage and dampness. A plastered finish was observed to be more effective than the 3-mm-thick stucco finish.
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The outline of any form of mortar bedding (thin jointing or conventional) resulted in higher dampness than dry-stacked specimens. For severe exposures, corresponding to a pressure of 500 Pa, plastering is effective in minimizing dampness and total leakage with all three types of bedding whereas the stucco finish is only effective with the dry-stacked specimen.
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Adjudging the overall behavior of plastered specimens (1) with respect to dampness, drystacked masonry performs better; and (2) with respect to leakage, thin-jointed masonry performs better.
Interlock Mechanism of Concrete Block Pavements In classic highway loading circumstances, the pattern of stress progress in paver bedding sand is complex and depends upon the size, shape, orientation, and speed of the load as well as paver geometry and laying pattern. Many of the previously unsolved bedding sand failures can be assumed by examining the way in which local vertical stress transient develops and travels through bedding sand. In cases where water is present in sands including a significant fraction of fine material, the mechanism whereby sand instability can develop has been clarified. Fast changing stress levels can result in pressure developing in water in bedding sand, which can lead to instability. It is recommended that sands should be specified which permit water to flow as freely as possible where traffic and water may occur concurrently. The data relating pavers to different geometries indicates that there are differences in the performance of different pavers although the effect is likely to be of minor structural consequence. The only exception to this is the variance between chamfered and no chamfered pavers. By forcing the load patch inboard of the paver perimeter, chamfered pavers reduce bedding sand stress levels and are therefore to be favoured in trafficked pavements. (Algin, 2007)
Surface Integrity of Blocks used on an Aircraft Pavement in Australia To avoid the incidence of potential Foreign Object Damage (FOD) to aircraft engines and machineries, it is important that the surface of the pavement to be strongly bonded. The surface of the blocks should not contain weakly bound aggregate particles or voids in order that
concentrated loads do not break or chip the surface. In the initial trial, a important number of blocks with honeycombed surfaces were provided and built into the works in spite of the blocks apparently meeting all the requirements specified in MA20. These honeycombed blocks resulted in the breaking out of aggregate particles under traffic. To overwhelm this condition in the new international apron works, a maximum average surface texture value for the blocks was necessary. A improved sort of the standard sand patch test was used to assess the adequacy of samples. A range of block surface textures were visually evaluated as to their acceptability and the average surface texture depth was measured. A value of 0.11 rom was set as the maximum average surface texture depth permissible. It was found that the test technique was not sufficiently repeatable to be assured that acceptable control of quality in this respect was possible. So, visual contrasts with accepted samples were used as acceptance criteria. (F. Vroombout, 1992)
Study on Heat Island Mitigation on Interlocking Block Pavement. (KIMIJIMA, 2009) This study examined the differences in sensible heat flux from the surface of permeable IL block pavement versus normal and permeable asphalt pavements, to defining whether permeable IL block pavement may be able to diminish the heat island effect.
The findings are
potted as follows: •
The calculated surface heat budget showed that the permeable IL block pavement sample attained a lower sensible heat flux than the normal and permeable asphalt
pavement specimens. The difference was 270 W/m2 at maximum and 80 W/m2 on average. •
It can be ended that permeable IL clock pavement may be effective at justifying the heat island effect.
Evaluating Surface-Breaking Cracks in Concrete Using Air-Coupled Sensors (Seong-Hoon Kee, 2011) In this study, the air-coupled SWT method was established to evaluate surface-breaking cracks in in-place concrete structures. The findings obtained from this study are revealed as follows: •
Contrast analysis shows that the air-coupled sensors substantially improved the test speed measurements of in-place concrete structures compared to the contact sensors.
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The SWT method can be prolonged to global check using the MSC procedure. Using the MSC procedure, 1-D and 2-D transmission maps were found to identify the presence of surface-breaking cracks in concrete. The 1-D transmission map was revealed to be effective in classifying cracks normal to the test direction.
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The depths of the critical surface-breaking cracks in concrete structures were expected by the simplified SWT method suggested in this study. Contrast analyses showed that the estimated depth from the SC and MSC procedures matched fairly well with the results measured from core samples directly extracted from the surface of the concrete beams. The results presented in this study showed that the simplified SWT procedure is a potential method to estimate the depth of a surface-breaking crack in in-place concrete structures.
INNOVATIVE ADDITION OF POLYPROPYLENE FIBRE IN INTERLOCKING PAVER BLOCK TO IMPROVE COMPRESSIVE STRENGTH (BHAVIN K. KASHIYANI, 2013) In this study, advanced addition of polypropylene fibers only in the top layer (15 mm) of paver block for determining the change in the compressive strength of paver blocks and decreases the maintenance cost of paver block. From this study, the following conclusion can be ended: •
The addition of a 0.4% fiber in the top 15 mm of paver block gave
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The optimum compressive strength.
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By addition of polypropylene fiber, it improves the strength up to 40% and reduces the water absorption.
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It makes paver block more dense compare to standard concrete paver blocks.
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By addition of paver block, it also improves the other properties like abrasion resistance, durability, tensile and flexural strength of paver block.
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A small increase in cost related to standard paver block but increases the features of concrete paver block and life span of paver block and reduce the maintenance.
Proposed Structure and Construction Method for Improved Interlocking Concrete Block Pavement Used in Residential Parking Spaces (Akihiko Karasawa, 2012) In this study, the authors recognized the cause of deformation, and propose a new ILB pavement structure and construction method to ensure high serviceability for residential parking spaces as summarized below:
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The offered pavement structure includes special materials: georgic over the reburied utility pipes, reinforcing nonwoven fabric between the subgrade and the base course and also between the base course and the bedding sand, as well as around the check-up chamber at the ground surface.
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The crusher-run material in the base course of the offered construction method should be divided into two layers; the water content of each layer should be kept at the optimal condition and the same area should be compacted eight times using a medium-size vibration roller of 150 kg in mass.
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The contrast of deflection amount dignified by HFWD showed that the pavement using the offered structure/construction had less deflection than the pavement using the conservative structure/construction. This proved that a higher bearing capacity could be found with the proposed structure and construction method.
Our Term Paper Project:
Many aspects of interlocking concrete pavements surface deterioration are to be taken under consideration among this paper study. Duties to be equally distributed among the group, so every member have the responsibility to cover a main aspect that surrounds our project. Surface deterioration of ICPs to be discussed as a definition, mechanically and automatically installments, stress effects, hot weather effects, high moisture effect, underlay soil materials, minerals effects, and possible solutions.
CHAPTER 3: Problem Identification Process Problems This process is for some materials which used to produce and make all the finished concrete structure. These materials are different from the product and it should not be confused, that focus more on mix design and constituents. Process problems are caused by many reasons such as: •
Using of some materials such as impermeable formwork which contact materials coated by release agents.
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Using weak and poor quality spacer blocks.
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using wrong compaction, curing methods, and wrong placing
Damage to concrete Damage to concrete is a process problems that can affect many properties of the concrete surface and this damage can go up to a depth of 20mm. By using some oiled impermeable such as steel, plastic and plywood formwork face materials, all of this will results in water gain, trapped air bubbles and cement reduction.
Surface Blemishes Blemishes on a concrete surface can happen due to process problems. Blemishes can be related to the air and water that trapped at the surface which include: •
Some pinholes and blowholes.
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Plastic cracking and crazing.
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Oil discolouration, dusting and retardation.
Contaminated Surfaces Contaminated surface that have blowholes and contaminated with release agent residues that can make a good environment for biological growth to happen in this place. Some research showed that concrete surface could be penetrated if oil used with impermeable faced formwork. These chemicals are not related to UV degradation once its shielded from the surface. Traces of release agent provide many things such as nourishment for bacteria and fungi, contaminate the water supply and affect the use of applied coatings.
Porosity and Surface Cement Content Porosity, surface cement content and w/c ratio are affected by the type of the materials of the formwork face contact used in the outer 20mm of the surface. when strength, admixture used and formwork orientation mixed, this results on the surface cement content is reduced by 40 Kg/m3 while the whilst porosity and w/c ratio are increased. So increased porosity and reduced resistance to the chemical attach can be done with reduced cement content and surface blemishes, which can call carbonation and abrasion.
Evaluating Surface-Breaking Cracks in Concrete Using Air-Coupled Sensors To evaluate surface-breaking cracks in concrete structures, there is a rapid in-place nondestructive test (NDT) method is used. To measure the surface wave transmission (SWT) across surface cracks in concrete we can use Air-coupled sensors. SWT method is used to determine the crack depth; also it can specify the damage of the cracks in the structures of concrete. The
advanced SWT method can be used to find and describe the cracks by three pre-stressed concrete beams with different degrees of corrosion that happened because of alkali silica reaction and delayed ettringite formation (DEF). The SWT results is shown as transmission maps and compared with cracks forms and the harshness of corrosion. The results of cracks depth that resulted from the SWT test are so similar to the same measurements of the core sample. The nondestructive test (NDT) is considered a very modern and advanced method to evaluate the cracks and the damages of the concrete structures and the most important is that we can do it rapidly, inplace and without causing the damage of the concrete samples and structures. (Kee, 2011)
Concrete surface preparation using gelled acid Gelled acid could be used for concrete surface preparation. This method of chemical preparation is used to protect the surface of concrete form the acid fumes, water spray and dust. This method defines coating, finishing and surface preparation. (Hunter, 2005)
The Importance of Curing The layers for curing zone are different due to some reasons such as the type and the duration of the curing employed and it is almost between 20mm to 50mm. Curing is very important and it is the important part of making a durable concrete structure. To improve the concrete surface by good curing can be done by many ways such as reducing porosity and increasing resistance to carbonation, abrasion and chloride ingress. Curing is very important for concrete with blended cements, such as GGBS, PFA and micro silica. Porous surface can be produced by conventional oiled formwork which is an immediate significant moisture loss. Less
effective curing result in the delay time between installing a curing regime and formwork removal.
The Importance of Cover The type and quality of the depth of the cover is very important. Also it is hard to achieve the design cover, with less of over 15mm common. The less in cover related to the poor quality outer 20mm, that will results in reinforcement corrosion, even if the design is well and placed mix.
Controlled Permeability Formwork (CPF) A CPF liner is consist of two or one layer system collected from particularly engineered filter fabric bold to a web or drainage fabric. The thickness of Product is usually a lesser amount of(less than) 2.5mm. The filter material Must have a pore size lesser than 0.050mm, to support keep the cement fines majority, whereas permitting the measured elimination of extra water and air from the concrete/formwork border. Porosity of liners should be slight to avoid the much water being detached, that might be ferocious to the surface after using low water cement mixture. 0.1 litres/m2 for liners of a maximum absorbency has been recommended. There are also Some liners also recollect water inside structures to help with initial drying or curing. Sometimes Liners are always secure to conservative formwork by using suitable tensioning strategies or devices. However, Mediators or agents must not be used either on the liner itself or on the formwork. After involved to the formwork, concreting start accomplished in the standard mode. Liner reclaim will hinge on upon facing or lining category and the probable benefits, For instance Type 2 liners are used barely one to two times , whereas Type3 liners can be used three
to four times for full durability developments, while additional uses of Type three linings will continue giving a level of durability development whereas virtually removing maximum external blemishes.
CHAPTER 4: Solutions
Maintenance: The most familiar method for maintenance is the potential clogging that can be used for joints between the pavers and the opening. Some fine particles are on the surface from the vehicles and runoff because it can close the opening. This closing for the opening will increase during time and use. Although the opening will have many particles from the pavement surface, it will not close or become impermeable. Although we have an initial infiltration level, the capacity of the long-term infiltration will stay high. Surface infiltration rates will increase 1 inch/hour when it is almost clogged and closed. Permeability can be more in many ways such as changing the aggregate between the pavers and extreme circumstances.
Avoiding Surface Blemishes What are the surface blemishes? The blemishes that usually get up from water and air improvement either on the “oiled plywood or steel formwork” Faces can be avoided by the use of CPF. Which it can be put on both vertical and sloping formwork, the final usually makes several blemishes on conservatively cast surfaces. However, it has been notice that CPF cast surface is lightly stones blasted, that uniformly fewer blowholes are open.
Avoiding Surface Contamination The benefits can be arising by a CPF liner, with the non-use of release agents, a low Porosity surface with bigger cement content and nominal blemishes, provide the surface, that can reduces by organic species the risk of contamination, The resultant surface stays aggressive to growing of algae in a micro-organisms and marine environment in water absorbent constructions. 7 year old of Site testing the marine structure has been shown that for the splash zones and inter-tidal, algae growing on the CPF cast surface is negligible or minimal, while the conventionally cast surface has been deeply occupied. Several structures in water plants have been studied after more than 15 years in Procedure, they show negligible algae growing in dry, and wet environments on the CPF cast Surfaces. That is not the situation for surfaces cast compared to plywood-faced formwork.
Improved Surface Cement Content & Porosity Reduction in cement content and increases in w/c ratio and porosity can be show the reduction in The outer 20mm of the surface cast against oiled steel/plywood faced formwork for all conditions regardless to strengths mixture . The opposite is correct for CPF compared to surfaces cast. There is a improvement in cement content and decreases in water cement ratio and porosity. The net rise in cement content for an oiled plywood or steel cast surface is more than 100kg/m3. The resultant surface has developed durability and larger resistance to all forms of environmental occurrence, In two facility tanks in Ireland, that have been in process for 7years. Important differences were distinguished among the columns cast with plywood formwork and oiled steel and CPF cast walls. The walls remain natural, while for the columns, the blowhole
shave revived while the surface is slimy and sandy to touch because of soft water attack and the dirt adhering to the non-CPF cast concrete. The benefits use the CPF liner proves the difference in quality and durability of two surfaces fully.
Performance of CPF cast concrete in harsh environments Reinforced concrete structures in hot climates depreciate faster than structures in more moderate areas. The increased presence of chlorides in hot/wet and hot/dry environments atmosphere is mostly hurtful to concrete. Sometimes laboratory work on pretend hot climate environments has shown that concrete cast compared to CPF liner durability has been improved. The original preserving benefits of the liner incline to desensitize the concrete to the normally incompetently useful traditional curing. Reduced of porosity surface means that the CPF use will be of benefit irrespective of the type mix, for cement replacement or admixture that is used. The use of CPF in hostile chloride rich environments is equal to increasing the concrete rating by 15 N/mm2. For carbonation, the use of CPF might well remove the durability material necessities with the Total benefit associated to15mm of cover.
Performance of CPF cast concrete with Time The results suggest that, after 7 years in facility the properties of durability of concrete cast using Zemdrain® formwork lining continue much better than concrete cast beside normal plywood shuttering. Marine structure results presented that uses of CPF compact chloride access by 40% at the surface to 80% at depth. For both splash and inter tidal zones. Comparisons with connected laboratory data recommended that the benefits of CPF are preserved under aggressive exposure environments and they are equal to increasing cover depth by 15-20mm.
Fibre Concrete Accessories as an adjunct to more durable surfaces Fibre concrete accessories have many significant benefits over site cast or plastic equivalents: •
Consistent high compressive strength - compared with non-factory cast products
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Excellent dimensional tolerance - compared with non-factory cast products
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No deformations due to temperature fluctuations - unlike plastic spacers
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Excellent bond to concrete - plastic spacers and distance tubes have no bond
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Excellent chemical and physical resistance - unlike plastic and site cast spacers
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High resistance to mechanical and thermal loadings
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Fire resistant and non-flammable - unlike plastic spacers
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Spacers - remain in position during formwork erection and concreting
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Spacers – simple, rapid and economical to fix
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Spacers – reduced impact of spacer on the concrete surface
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Spacers – production of small quantities is possible
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Spacers – can be produced with & without tying wire, steel or plastic clips
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Spacers – special dimensions and shapes can be produced quickly
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Spacers – conform to recognised international standards
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Distance Tubes – large contact area thus reduced pressure on the formwork
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Distance Tubes – can be manufactured as impermeable shutter ties to 30bars
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Distance Tubes – provide sound proofing due to their long seals
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Distance Tubes – provide a continuous seal for gastight bunkers and shelters
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Stoppers – ensure durable sealing of tie bolt holes
Long-Term Performance of Epoxy Coated Clay Bricks in Sulfuric Acid Recently, a new and advanced type of coating is used in the restoration and protection against the acid attack in industrial and wastewater facilities made of concrete surfaces and clay blocks. This coating is called Epoxy-based coating. Many types of tests are done of the Epoxy-based coating over a period of three years. The results of the tests showed that the Epoxy-based coating bonding strength depends on the wet and dry surface situation of the clay bricks at the time of coating process. The results showed also that the bonding strength of the Epoxy-based is 0.2 MPa to 3 MPa. The process of Epoxy-based coating is working as a protection and isolation of the surface and clay bricks against water penetration through it. Keywords:
brick,
clay,
coatings,
bonding
processes,
mechanical
strength,
modelling
CHAPTER 5: Summary and CONCLUSION
Summary The paper discusses Interlocking-blocks surface cracking and deterioration. Literature review and researches have been done according to this subject also discussed briefly with other topics related to the problems and solutions. Problems such as: Process Problems, Damage to concrete, Surface Blemishes, Contaminated Surfaces, Porosity and Surface Cement Content, Evaluating Surface-Breaking Cracks in Concrete Using Air-Coupled Sensors, and gelled acid. And Solutions such as: maintenance, Avoiding Surface Blemishes, Avoiding Surface Contamination, Improved Surface Cement Content & Porosity, Performance of CPF cast concrete in harsh environments, Performance of CPF cast concrete with Time, Fibre Concrete Accessories as an adjunct to more durable surfaces, and longTerm performance of Epoxy Coated clay bricks in sulfuric acid.
Conclusion Nowadays the presence of the interlocking tiles is increasing rapidly and it's covering very large areas of the cities and villages in the world. The daily demand of the interlocking tiles is very big and that is because of many reasons. The production of the interlocking tiles in the cement products factories is considering very easy. The interlocking tiles are made from four ingredients: 1- Dry mix of gravel. 2- Cement. 3- Sand.
4- Desired colour for aesthetic purpose.
The ingredients are mixed together by adding very little water to it. The mixture is then moved on conveyor belts and then funnelled into the pavers mold. Pressure is applied to the mixture in the mold and the mold is vibrated. Pressure and vibrations cause the water to set which helps in binding the aggregates together. Further, the mold is removes and perfectly finished pavers are obtained. Many colours and shapes of the interlocking tiles could be made. Moreover, the installation process of the interlocking tiles is so easy and it could be finished in a very shorty period of time. But, there is a serious problem in the interlocking tiles happens at the coastal areas and high temperatures lands. The interlocking tiles that located in the mentioned area are suffering from humidity corrosion and chemicals attack in the soil affecting the upper weak layer of the interlock block. But the base layer consists of very strong concrete which doesn't allow corrosion in it. The presence of the water in the air due to high humidity allows the water drops penetrates the surface of the interlocking tiles and weaken its upper layer until its corroded. Besides, chemical attack in the salty soil causing corrosion in the concrete mix of the interlocking tiles. Many solutions can be done to prevent this problem or to repair it. To repair this problem a concrete layer of 1 cm thickness could be designed and cast in the place to replace the upper corroded layer. This concrete layer must be designed to resist shrinkage failure and crakes and must be too strong to handle the standard weight upon it. Another solution could be taken before this problem even happen is to isolate the interlock blocks below it from the salty soil to avoid chemical attack that cause harm damages. Besides,
many types of sealers and polymers could be used to cover the upper surface of the interlocking tiles from water penetration and humidity.
References: Akihiko Karasawa, M. N. (2012). Proposed Structure and Construction Method for Improved Interlocking Concrete Block Pavement Used in Residential Parking Spaces. 10th International Conference on Concrete Block Paving (p. 8). Shanghai, Peoples Republic of China: CPI-Worldwide. Algin, H. M. (2007). Interlock Mechanism of Concrete Block Pavements. JOURNAL OF TRANSPORTATION ENGINEERING © ASCE, 9. BHAVIN K. KASHIYANI, J. P. (2013). INNOVATIVE ADDITION OF POLYPROPYLENE FIBRE IN INTERLOCKING PAVER BLOCK TO IMPROVE COMPRESSIVE STRENGTH. International Journal of Civil, Structural, Environmental and Infrastructure Engineering, 10. F. Vroombout, R. M. (1992). THE USE OF INTERLOCKING CONCRETE BLOCKS ON AN AIRCRAFT PAVEMENT IN AUSTRALIA. Proc. 4th Int. Conf. On CBP (p. 14). Washington / USA: Interlocking Concrete Pavement Institute . Hunter, D. A. (2005). Concrete Surface Preparation Using Gelled Acid. Retrieved from EBSco: http://search.ebscohost.com/login.aspx?direct=true&db=aci&AN=501161970&site=ehost -live Jr, B. J. (1996). Interlocking concrete pavers: The manufacturing process. the concrete producer, 4. Kee, S.-H.-G. E. (2011). Evaluating Surface-Breaking Cracks in Concrete Using Air-Coupled Sensors. Retrieved from EBSco: http://search.ebscohost.com/login.aspx?direct=true&db=aci&AN=525496267&site=ehost -live KIMIJIMA, T. (2009). STUDY ON HEAT ISLAND MITIGATION ON INTERLOCKING BLOCK PAVEMENT. 9th. International Conference on Concrete Block Paving (p. 9). Buenos Aires, Argentina: Argentinean Concrete Block Association . Ramamurthy, K. B. (2001). Influence of Construction Method on Water Permeation of Interlocking Block Masonry. JOURNAL OF ARCHITECTURAL ENGINEERING, 5. Seong-Hoon Kee, E. F.-G. (2011). Evaluating Surface-Breaking Cracks in Concrete Using AirCoupled Sensors. ACI MATERIALS JOURNAL, 9.
