Demolition Of Old Structures Research Articles

Influence of plastic coating temperature on recycled concrete brick coarse aggregate

The generation of waste from the demolition of old structures poses a significant environmental challenge. Recycling these materials as aggregates in concrete offers a potential alleviation of environmental impact. While recycled aggregates offer promise as a remedy, they are not without drawbacks. However, innovative approaches have been developed to overcome these limitations. Among these, plastic coating stands out as a particularly sustainable solution. This study investigates the influence of plastic coating temperature on recycled concrete brick aggregates (RCBA), which serve as coarse aggregates. The RCBA were coated with locally sourced polyethylene terephthalate (PET) at varying temperatures, such as 250 °C, 300 °C, 350 °C, and 400 °C. Then the physical properties of the plastic-coated recycled aggregates (PCRA) were assessed. Additionally, concrete specimens incorporating PCRA were fabricated to evaluate their influence on the mechanical properties of concrete. The results indicate that higher coating temperatures positively influenced the physical properties of the aggregate. Furthermore, at elevated temperatures, the plastic became sufficiently malleable to penetrate deeper into the permeable pores, reinforcing the weak mortar interface and thereby enhancing the mechanical properties of the concrete made with it. Additionally, mathematical models have been proposed to predict the influence of plastic coating temperature on both the physical properties of the RCBA and the mechanical properties of the concrete.

Experimental Study on Partial Replacement of Natural Coarse Aggregate with Marble Waste Aggregate in Concrete

Abstract: Marble waste is produced from marble industries as a result of production. More production equals more waste, more waste creates environmental contamination. A high volume of marble production has generated a considerable amount of waste materials; almost 70% of the minerals gets wasted in the mining, processing and polishing stages which have a serious impact on the environment. Also, a large amount of marble is accumulating in the environment due to demolition of old structures having marble. This causes environmental pollution. An economically viable solution to this problem should include utilization of these waste materials for new products especially in construction applications which in turn minimizes the heavy burden on the nation’s landfills, saves natural resources, energy and reduces environmental pollution. Present study work is concerned with studying the feasibility of partial replacement of coarse aggregates with marble waste. Varying percentages of replacement is considered 0%, 10%, 20%, 30%, 40% and 50% by natural aggregate, From the results of current experimental study, it is concluded that Compressive strength of the concrete cubes at 7 and 28 days shows 29.87 and 41.89 N/mm2 till 40% marble waste coarse aggregate used as replacement of coarse aggregate in concrete. Hence the marble waste coarse aggregates can be used in concrete works up to as 40 % replacement.

IMPACT OF GEOTEXTILE ON THICKNESS OF ROAD LAYERS

There is considerable promise for geotextiles, a new field in civil engineering and other fields, with a wide range of applications around the world. Modern pavement design and maintenance rely heavily on the use of geotextiles. The exponential rise in its use, particularly in transportation, around the globe has been nothing short of astounding. Using geotextiles as a building material for infrastructure projects such as roads, harbors, and many others is a great concept. In the future, they will have a bright future because of their multifunctionality. This study focuses on the use of geotextiles in the construction of pavements and the use of Recycled Concrete Aggregate (RCA) to construct new roads which will drastically reduce the strain on our natural resources and this also will provide us an effective way of managing the waste produced by demolition of old structures. RCAs are not easy to work with and do not produce the results as good as natural aggregates because of presence of old adhered mortar around it hence geotextiles are used to enhance their performance and improve the overall CBR value of road

Effect of 6 Hour Fire on Flexural Strength of RC Beams made with 50% Coarse Aggregates from old concrete: Part 1: Normal mix

Shifting of people from villages/small cities to big cities poses a serious issue of accommodation and other associated infrastructure. For the solution of said issue, demolition of old structures to construct new high-rise buildings is opted. The demolishing waste is an additional problem for the project, particularly due to unavailability of the dumping space in many areas. A method of addressing the issue is by using it in new concrete. This research study presents an experimental investigation to check the effect of a 6-hour fire at 1000◦C on the bending resistance of reinforced concrete beams prepared by replacing 50% conventional coarse aggregate with coarse aggregate from demolished concrete. 24 RC beams of 0.9m × 0.15m × 0.15m size are cast using 1:2:4 mix and 0.54 water cement ratio. To reinforce the beams 2#4 bars in each tension and compression zones are used. Out of 24 beams, 12 are cast with all-natural coarse aggregates to compare the results. After 28-days standard curing, all beams are exposed to fire for 6 hours in purpose made oven. The beams are then left at room temperature for 24-hours followed by testing of all the beams in universal load testing machine with central point loading. Load and deflection are monitored at regular intervals. Comparison of the results with control specimen shows that the proposed beams observed 13.43% reduction in flexural strength which is quite smaller. The beams failed in shear which complies with the failure mode of normal concrete beams. Thus, the proposed material has good fire resistance when used in reinforced concrete beams.

Improve Recycled Concrete Aggregate properties in Order to Use It in Paving Application as Aggregate

The amount of crushed cement concrete continues to increase daily as a result of the demolition of old structures, thereby increasing pollution. To cope with the pressure imposed by the rise in environmental awareness and the stringent disposal regulations set by environmental protection agencies, effective measures for handling and disposing of crushed concrete must be implemented. Instead of simply disposing of crushed concrete, alternative efforts should be considered to utilize it as a recyclable material. The objective of this study was to improve recycled concrete aggregate (RCA) to be able to using it in paving application. Three types of treatments applied to improve RCA properties. In this study three types of treatment were used to improve RCA properties. Theses treatment are soak RCA in HCL acid for 24 hours, grind RCA in Los Angeles Abrasion machine, re-grind RCA particle in jaw crush machine. In order to evaluate each treatment the aggregate properties are determined. All properties were determined for RCA passing and retained sieve size of 5 mm and 1.18 mm respectively. The calculated properties are bulk specific gravity of aggregate, absorption value, abrasion value of aggregate and angularity number of RCA. The most important conclusions are Soaking RCA in HCL acid has side effect on the specific gravity of aggregate, Putting RCA in Los Angeles Abrasion machine make RCA particles more rounded. Finally, crush RCA in jaw crusher machine for second is best way to improve RCA properties.

Failure of horizontal support system to adjacent buildings during reconstruction in Eskisehir

Approximately, 65% of the existing residential structures are adjacent in Turkey. In addition to the social disadvantages of living in adjacent buildings, these structures are prone to pounding during earthquakes and they are under threat during the construction and demolition of the neighboring structures. The neighboring structures may experience damage during/after the demolition of adjacent structures due to pounding of structural components. There are many cases of casualties and economic losses due to the collapse of neighboring structures during the demolition of old structures. The damage can be occurred as a result of constructing shared foundations, different foundation depths, the groundwater level, and possible impact of the work machine during demolition. Also, in areas with high seismic risk, there is a possibility of an earthquake at a time between the demolition and reconstruction stages of a building, which can cause significant damage. Due to these reasons, the design and construction stages of adjacent structures should be described by building codes in detail. In order to renew the adjacent structures at different times, horizontal support elements should be used and required design calculations should be made. This study examines the truss system applications as horizontal support in such structures built in Eskisehir. The characteristics of the section and system properties, the horizontal load carrying capacity, the choice of support zones between the adjacent structures, and the characteristics of strain deformation are determined. It is concluded that the horizontal support applications prevent horizontal forces due to earthquakes and various vibrations in neighboring structures and prevent structural deformation.

Crushed Limestone Waste as Supplementary Cementing Material for High Strength Concrete

Use of greener materials and gaining popularity of environment friendly materials worldwide has led to newer research in utilizing waste materials produced from various human, agricultural and industrial activities for useful purposes. Agricultural wastes like rice straw and husk, industrial wastes like slag, fly ash, crushed stone, limestone waste and brick/ concrete waste from demolition of old structures are extensively being used in manufacturing concrete. This experimental study aimed at evaluating the properties of widely produced waste material from limestone processing industry with no beneficial usage i.e. crushed limestone waste as supplementary cementing material. For years a small percentage of limestone powder has been used in cement and masonry to improve workability and in concrete as fine filler however limited research has been carried out on high strength concretes with partial replacement of limestone crush as supplementary material. This study investigated the properties of high strength concrete made from Portland slag cement comprising 50% cement and 50% ground granulated blast furnace slag, natural aggregates and sand where crushed limestone waste was added to cement by replacing slag cement in the percentages of 10% and 20%. Wide ranging investigations covering most aspects of mechanical behavior and permeability were carried out for various mixes for compressive strengths of 60MPa and 80MPa. Compressive strengths of concrete specimen with partial replacement of 10% and 20% limestone waste were observed to be higher by about 4 to 12% than the control specimen. Flexural strengths were also observed to be higher by 12 – 13%. Higher elastic moduli and reduced permeability were observed along with better sulphates and acid resistance. Better strengths and improved durability of such high strength concretes containing up to 20% limestone waste make it a more acceptable material for major construction projects in addition to consuming this massively produced waste material for useful purposes along with reducing its disposal problems.

Valorisation of recycled concrete sands in cement raw meal for cement production

The demolition of old structures in concrete generates materials which can be recycled in the form of aggregates for new concrete, thus preserving natural resources. These recycled concrete aggregates are composed of natural elements bounded with hardened hydrated cement paste. The fine fraction (sands and fillers) is however more difficult to reuse than aggregates because it contains a high proportion of cement paste which absorbs a lot of water. The recycling of these products in the cement process is an interesting alternative way. In this paper, the possibility to use recycled concrete and fine material from de-dusting process of crushing platform for demolition concrete as alternative raw material for cement production was investigated. After a full chemical characterization of the recycled concrete sands and fines (XRF, XRD, DTA-TGA…), several cement raw-mixes were prepared by substituting partially or fully clay or marl. The generated clinkers have been characterized by different analytical techniques (TGA/DTA, XRF, XRD, SEM…). If the chemical composition of the raw is well balanced, the substitution of one of the cement raw meal components by recycled concrete sands does not affect the clinker. However, the free lime content may vary, including the initial quartz content of the recycled concrete sands used.

USE OF SCC AND RCA FOR SUSTAINABLE CONSTRUCTION - AN OVERVIEW

This paper presents a brief review on the sustainab ility in building construction, environmental prote ction with respect to construction industry, constitutional provisions of environmenta l act and issues of environmental management plan ( EMP). Also, Special emphasis is given on use of Self-Compacting Concrete (SCC) a nd Recycled Concrete Aggregate (RCA) for sustainabi lity. SCC has significant environmental advantages in comparison to the vibra ted concrete; absence of noise pollution and vibrat ions during construction provides a healthier working environment. In this p aper, the potential for usage of coarse recycled ag gregate obtained from crushed concrete for making self-compacting concrete was di scussed, emphasizing its ecological value. The use of RCA contributes to the environment by solving the issue of waste disposal due to the demolition of old structures and also co nserving the natural resources (Coarse Aggregate).

Properties of self-compacting concrete prepared with coarse recycled concrete aggregate

Self-compacting concrete has significant environmental advantages in comparison to the vibrated concrete: absence of noise and vibrations during installing provides a healthier working environment. In the paper the potential for usage of coarse recycled aggregate obtained from crushed concrete for making of self-compacting concrete was researched, additionally emphasizing its ecological value. On the other hand the issue of the waste disposal sites created by the demolition of old structures is solved. In the experiment, three types of concrete mixtures were made, where the percentage of substitution of coarse aggregate by the recycled aggregated was 0%, 50% and 100%. In the process of mixing, equal consistence of all concrete mixtures was achieved. The obtained results indicate that the properties of these concretes have only a slight difference, and that the recycled coarse aggregate can successfully be used for making of self-compacting concrete.

Albania: vortices of imbalance

The transition to a market economy in Albania is a relatively long and complex process. It is characterized by the demolition of old structures and the establishment of new ones, often in parallel, until a new, completely different economic system emerges. During this difficult and innovative process, a myriad of interconnected problems have arisen; one of them is massive emigration, a phenomenon not seen in Albania since World War II.