Concrete Mold Research Articles

Study on the Hydration Heat Effect and Pipe Cooling System of a Mass Concrete Pile Cap

Under the action of cement hydration heat, the construction environment, thermal insulation measures, and pipe cooling systems, a mass concrete pile cap is subject to a complex internal temperature field, which makes it difficult to control its internal surface temperature difference (TISTD), the internal adiabatic temperature rise (TIATR), and the surface temperature (TST). In this study, a mass concrete pile cap of a very large bridge (the length, width, and height were 26.40 m, 20.90 m, and 5.00 m, respectively, and the central-pier pile cap was constructed with C40 concrete) was taken as the research object. The control factors affecting the temperature field of the pile cap were determined by comparing the field temperature measurements with the values calculated with finite element software simulation analysis. By using Midas Civil (2022 v1.2) and Midas FEA (NX 2022) finite element software, these factors (the concrete mold temperature, the concrete surface convection coefficient, the ambient temperature, the pipe cooling system parameters, etc.) were numerically analyzed, and their influence laws and degrees were determined.

Synergic Effects of Recycled Concrete Aggregate and Styrene Butadiene Rubber (SBR) Latex on Mechanical Properties of Concrete

These days Sustainable advancement is picking up notoriety all around the globe. To hold characteristic assets, reuse and reusing of development and annihilation squander is the clearest approach to achieve manageability in the development division. Presently, reused aggregate RA is been generating and CDW is its source. As of late, these squanders are reused in present day reusing offices, under great quality control arrangements which could prompt enhance its execution. An investigation is completed about the characteristics of Recycled Aggregate Concrete RAC by utilizing squashing and breaking of concrete waste got from various obliteration locales & junkyard. With the end goal to upgrade the characteristics of RAC there are a few additives called as super plasticizer which are adjoined with concrete. Fixings utilized in particularly this investigation were ordinary sand, common & reused aggregate & additive namely Styrene Butadiene Rubber latex (SBR). Those aggregates are acquired from various assets. Sum of 144 concrete molds in system of 4 collections was framed. Gatherings were structured in such a route along these lines, to the point that the impact of reused coarse aggregate (half, 75 percent, and 100 percent), cement dose and expansion of latex of SBR in factor amounts by the cement weight of (0.5 percent, l percent, 1.5 percent) ought to be appropriately decided. For compressive quality and rupture modulus MOR, tests were done. Prior to the tests performance in the research center a diminishing pattern of twenty five (25) percent in compressive quality was taken note. An impressive decrease was seen in the properties of RAC by utilizing 100% reused aggregate when contrasted with Natural Aggregate Concrete NAC. There was negligible change in Recycled Aggregate Concrete RAC made of 75 percent (%) NA and 25 percent (%) RCA. Yet, there was ideal properties differences of concrete ended with the blend of half NA and half RCA. It was seen in the outcomes that concrete squanders might be used in arrangement of concrete subsequent to reusing them which at that point can be utilized in many concrete structures.

The application of C–S–H accelerators in the precast concrete industry: Early-age properties and CO2 footprint analysis

This paper investigates the effect of artificially synthesized C–S–H accelerators (CAs) on concrete properties and analyzes their potential advantages for the precast concrete industry. The study found that adding CAs improves the workability of concrete while also significantly boosting its early compressive strength (particularly within 24 h). This characteristic showcases the dual-effect nature of CAs as additives. Notably, adding 1.5 wt% (relative to the weight of cement) CAs may boost the 6-h strength of concrete to 16.6 N/mm2, meeting the conditions for demolding. This could allow precast concrete plant molds to complete four turnovers within 24 h, thus improving production capacity. Importantly, using CAs may eliminate the need for heat curing during production, thereby reducing the carbon footprint and energy use in the manufacture of precast concrete.

An Experimental Investigation of a High-Density Concrete with Waste Ceramic Tiles Used as an Aggregate

Abstract: The use of waste material as aggregates in civil engineering applications is beneficial and increasingly desirable because it reduces the environmental impact and economic cost of mining, processing, and transportation operations. Therefore, this study focused on establishing the effect of crushed tile on the compressive strength of concrete. In this research investigation, ceramic waste tile waste was substituted for natural coarse aggregate in concrete to varying degrees from (0, 10, 20, and 30%), and the M-20 graded concrete was used to produce high density concrete. After 3, 7, and 28 days of the curing process, few number of new concrete mould were casted and evaluated about the Compressive Strength and Split Tensile Strength. The findings of these results showed that 35% replacement of naturally made coarse aggregate with the ceramic tile aggregate which contributes the higher compressive strength to produce the high-density concrete in construction industry.

Ultra‐high performance alkali‐activated slag as a reusable mold for light metal casting

AbstractLight metal die casting is usually performed using steel molds. However, these lead to a reduced quality of the casting due to the occurrence of metal corrosion on the surface and the incorporation of hydrogen into the casting as a result of required process chemistry. Ultra‐high performance concrete based on alkali‐activated slag can be used to produce mineral molds for aluminum casting. The use of reusable mineral molds not only enables the production of various thin‐walled geometries. The risk of metal corrosion is eliminated and the concrete molds can withstand multiple cycles due to their thermal stability and high strength, making them potentially superior to the already common lost mineral molds.

Finite element modeling of early-age temperature development of in-situ concrete under variable ambient temperatures

The early-age temperature rises in in-situ concrete, caused by the exothermic hydration of cement, poses a significant risk of thermal cracking in concrete structures. This issue is particularly critical in large-scale structures, where thermal cracking can lead to serious structural integrity issues. Therefore, the accurate prediction of the concrete hydration temperature development is paramount for predicting and mitigating early thermal cracking in concrete. However, one of the main challenges in predicting in-situ concrete temperatures is the significant effect of variable ambient temperature on cement hydration rates and concrete heat dissipation. To address this challenge, this paper presents a finite element modeling (FEM) approach that accurately predicts the early-age temperature development of in-situ concrete by adequately considering the effect of variable ambient temperatures. The model integrates the heat of hydration of the cement, the impact of ambient temperature variations, and the heat transfer through the concrete and insulation mould. The cement hydration rate under real-life ambient temperatures is simulated using an Arrhenius-based method, which mathematically adjusts the isothermal calorimetry curves to reflect the actual conditions. Additionally, the study investigates the inhibitory effect of Ground Granulated Blast-furnace Slag (GGBS) on the early hydration temperature of concrete, with experimental tests and FEM simulations conducted on concrete mixes where up to 70% of the cement was replaced with GGBS. The validity of the FEM model was confirmed through comparison with concrete semi-adiabatic tests, demonstrating that the model provides accurate predictions of the temperature development of in-situ concrete. Importantly, the results indicate that the adjusted isothermal calorimetry curves successfully capture the ambient temperature effect on the cement hydration rate. The results provide valuable insights for the design of concrete structures, particularly in preventing early-age thermal cracking.

Artificial reef effectiveness changes among types as revealed by underwater hyperspectral imagery

Artificial reefs (ARs) are designed to mimic natural habitats and promote marine life. Their effectiveness is however debatable and can depend on factors such as structural complexity and construction material. Old artificial reefs (OARs) were made of concrete mold of simple geometric shapes, limiting their ability to mimic the complexity of natural reefs. Recent advancements in three‐dimentional (3D)‐printing technology have enabled the creation of 3D‐printed artificial reefs (3DRs) with biocompatible material and complex structures that can better simulate the natural habitats. We employed underwater hyperspectral technology to estimate the performance of these reefs and compare the benthic photosynthetic signal of natural reefs (NATs) with those of ARs (OARs and 3DRs) in coastal area of the north‐western Mediterranean (France and Monaco Principality). We expected differences in reflectance signals between OARs and NATs, and signals closer to NATs in 3DRs than OARs. Underwater hyperspectral technology was able to detect higher chlorophyll‐a derived signals on NATs than OARs. Moreover, the magnitude of differences between 3DRs and NATs was smaller than that between OARs and NATs. Although ARs were not capable of mimicking natural reefs, the use of 3D‐printed ARs might ameliorate their effectiveness for coastal reconciliation.

Calibration of the limit equilibrium pillar failure model using physical models

The limit equilibrium model, used in displacement discontinuity codes, is a popular method to simulate pillar failure. This paper investigates the use of physical modelling to calibrate this model. For the experiments, an artificial pillar material was prepared and cubes were poured using the standard 100 mm χ 100 mm civil engineering concrete moulds. The friction angle between the cubes and the platens of the testing machine was varied by using soap and sandpaper. Different modes of failure were observed depending on the friction angle. Of interest is that significant loadshedding was recorded for some specimens which visually remained mostly intact. This highlights the difficulty of classifying pillars as failed or intact in underground stopes where spalling is observed. The laboratory models enabled a more precise calibration of the limit equilibrium model compared to previous attempts. Guidelines to assist with calibration of the model are given in the paper. The limit equilibrium model appears to be a useful approximation of the pillar failure as it could simulate the stress-strain behaviour of the laboratory models.

Effect of elevated temperature on Portland Pozzolona cement based concrete using Sulphonated naphthalene formaldehyde and Polycarboxylic ether as superplasticizer

The most extensively used structural material in the world for construction purposes is concrete. It has been observed that mineral admixtures like fly ash, rice husk ash, etc., when used in concrete improves its performance at high temperatures, but the role of chemical admixtures at such high temperatures has yet not been investigated. In the current study, experimental research was done to study the role of Sulphonated Naphthalene Formaldehyde (SNF) and Polycarboxylic Ether (PCE) based superplasticizers in concrete at elevated temperatures. Concrete mixes of grade M20, M25, M30, M35 and M40 were prepared with and without superplasticizers. The concrete cube mould samples were heated at elevated temperatures of 100 °C and 200 °C for 1 h and then removed from the oven and cooled to room temperature and further tested for compressive strength. It was observed that lower grade concrete performed better than higher grade at elevated temperatures and for each grade, the mix containing SNF showed an inferior response as compared to the other two mixes at 200 °C. It was also concluded that the PCE based superplasticizer increases the compressive strength at elevated temperatures as well as at room temperature for all grades of concrete. This study also focuses on checking the durability for different grades of concrete with and without superplasticizer via water absorption test. It was concluded that percentage water absorption decreases with increase in grade of concrete owing to higher cement content, and there was no effect of SNF and PCE based superplasticizers on durability of concrete.

Metode Konstruksi Jetty Untuk Melindungi Muara Sungai, Studi Kasus Sungai Bogowonto

The location estuary of the Bogowonto river is very strategic because it is on the west side of YIA airport (Yogyakarta International Airport). The condition of the Bogowonto river will directly affect the airport, especially related to flood conditions. The construction of an estuary is necessary to maintain sediment transport so that sediment buildup does not occur flooding. One of the constructions at the estuary to prevent this is the construction of a jetty. The use of jetty constituent elements can withstand seawater abrasion. Concrete is an alternative that is used with the consideration that it can control the shape, compressive strength, and weight. The elements that make up this jetty are in the form of blocks and tetrapods with a certain weight. The research was carried out by analyzing the work of tetrapod concrete as a constituent of jetty construction. Limited workplace conditions for storage and production require a proper cycle from production and storage to installation. The research was conducted by direct observation in the field and interviews with the work executors. The results of field observations obtained work methods carried out by executors by circulating concrete production with two methods, namely concrete with the addition of addictive materials and without the addition of additives. This additional material accelerates the concrete's initial compressive strength so that the concrete mold can be immediately opened and used again.

Structural behavior of damaged reinforced concrete beams under static cyclic loading

Bridges are regarded as one of the most important components of transportation infrastructure. More and more repairs, inspections, alterations, and construction processes are required to maintain safe usage due to increasing travel demands in addition to bridge infrastructure aging. In this paper, we will discuss the experimental investigation using five reinforced concrete beams to evaluate the effect of making damage to experimental beams under static cyclic loading to investigate their ductility and energy dissipation. The defective parameters taken into consideration in the experimental program were the gap in the concrete mold and mild steel at the middle bottom reinforcement. All tested specimens had the same cross-sectional dimensions. The concrete dimensions of the beams were 200 mm in width and 300 mm in height, and the beam's length was selected to be 2200 mm, having a clear span of 2000 mm between the supports, they were tested in positive bending using a 3-point bending load system. According to the results, when (RC) beams were subjected to any of the mentioned types of damage, they showed a significant decrease in ultimate capacities ranging from 3.03% to 19.31%. The ANSYS model shows an average difference with the experimental program within 4 % as an acceptable agreement.

THE USE OF GLASS-REINFORCED POLYESTER IN PRESTON BUS STATION

This article describes the use of glass-reinforced polyester (GRP) in Preston Bus Station in Lancashire, England, designed by Building Design Partnership (BDP) and completed in 1969. GRP was used both for concrete moulds that play a key role in enabling the construction of the building’s distinctive elevation, and for kiosks, signage and smaller fittings. A survey of articles shows that the use of GRP for concrete moulds enabled innovative and efficient construction and this practice continues to date. Some smaller fittings in GRP which were expected to be durable and maintenance-free have been modified, damaged, or removed, yet, others survive and are in a good condition. The legacy of the car park pay kiosks was to last as a prototype for a prefabricated sectional building system.

Design and Fabrications of Vibrating Table for Concrete Mould

Abstract: The proposed concept in this project is to use vibrations to replace human labor of eliminating air bubbles from concrete blocks with the help of a vibrating motor arrangement. Concrete is made up of aggregate, water, and cement in a composite form. They generate a mass fluid that can be easily molded into different shapes for varied functions when combined in certain ratios. Concrete must be free of entrapped air and voids to achieve the appropriate strengths. Concrete consolidation is used to accomplish this. The process of eliminating entrapped air from a concrete mold is known as consolidation. Unbalanced eccentric assembly, stand frame, top plate as platform, springs, spring suspension system, and electric motor are the primary components. A lot of mistakes should be made when a person works by hand. It also required lots of workers and production does not come in required amount during that day so the vibrating table will save time as well as money. The removal of these spaces enhances the exterior surface of the molded concrete, allowing for the use of less water with cement, resulting in a considerably stronger finished product, and this was accomplished using a vibrating table. The goal of this project is to build a concrete vibrating table that efficiently ensures concrete consolidation for a better product. These concrete molds can be used to make concrete roof tiles and concrete paving bricks. Although there are various existing vibrating tables, our job was to develop and maybe manufacture an improved vibrating table using locally available materials

Analisis Perbandingan Biaya Pekerjaan Bekisting Konvensional dan Bekisting Sistem Pada Bangunan Gedung

Formwork is a temporary concrete mold that holds the concrete from fresh concrete until the concrete reaches sufficient strength. Besides the strength and easy to implementation, the cost of formwork is important thing to consider. In this study, the cost of column, beam and floor slab formwork will be analyzed by comparing the conventional formwork and system formwork on the 1st floor of the IAIN Bukittinggi Laboratory Development Project.
 This research begins by collecting the main data, namely shop drawings so that the volume and also cost of formwork can be calculated. For analysis conventional formwork using the unit price analysis based on the PUPR Ministerial Regulation 2018, but for price of materials and worker wages based on the Bukittinggi area in 2019. While for system formwork, the rental price based on formwork and scaffolding company, PT. Wijaksana Perkasa Beton.
 The result of this study indicated that for the 1st floor of the Laboratory Development Project of IAIN Bukittinggi, the cost of system formwork is more expensive than conventional formwork, i.e Rp 381,260,039.29 for system formwork compared to Rp 336,629,299.41 for conventional formwork. The results of this study also have not compared of the speed and ease of carrying out the work between the two types of formwork which will be investigated in the next stage.

Comparison of the Performance of the Steel Fiber Shotcrete and Cast Concrete considering Accelerator Types and Core Sizes from a Tunnel Site

Shotcrete is considered a substantial long-term product providing a sheltered working environment for tunneling engineering. However, multi-functional problems occur due to the sprayed concrete construction method. Moreover, the performance of the shotcrete placement into the wall of the tunnel is challenging to verify. Currently, accelerators are used in highway tunnels for improving the overall performance of shotcrete. This study evaluated the tunnel shotcrete performance for cement mineral, aluminate, and alkali-free accelerators, as well as steel fiber, which is the main constituent of shotcrete. The workability of concrete and shotcrete in situ has been measured for these combinations. Using 1-month samples, shotcrete was evaluated by means of accelerating agent, compressive strength, core compressive strength, flexural strength, and flexural toughness. In particular, 37 kg and 40 kg of steel fiber were included into the cement and aluminate mix and the alkali-free mix, respectively. Changes in strength and flexural performance of shotcrete were studied under Korean standard. Thus, concrete cylindrical molds were manufactured for the compressive strength test. After 28 days of curing, concrete and shotcrete test panels were manufactured for core compressive strength tests on cylindrical molds with diameters of 100 mm, 75 mm, and 55 mm. Furthermore, beam samples were produced for flexural strength and toughness tests to measure the shotcrete performance. Air void test and steel fiber remaining percentage after shooting were performed to ensure the performance image analysis. Alkali-free incorporated with steel fiber is the best combination for tunnel shotcrete premised on compressive strength, core compressive strength, flexural strength, and toughness test results, along with environmental and worker safety. Finally, the tunnel shotcrete performance was evaluated by regulating and improving the accelerator type with the steel fiber for shotcrete.

Experimental tests to validate the usage domain for personalised formworks

Analysing the nowadays tendency for customised products, the personalised formwork is a solution that is worth taking into account. Not only that the concrete mould (due to the composite membrane) can take various shapes, function of the designer’s requirements, but it can be reusable and remodelled at each usage. By using the Product Lifecycle Management (referred as PLM) principles, two directions were analysed: a pushing system without any auxiliary reinforcement of the formwork and a pulling system with additional reinforcement under the formwork membrane. The composite membrane is subjected to multiple tests with different variants. By analysing the resulting values regarding the final shape of the product (concrete element), the proposed solutions were validated by defining the usage domain for each type of personalised formwork.

An Innovative Approach on Pet Bottles Compiled with Waste Materials to Produce Eco-friendly Concrete

PET bottles, such as water bottles, cool drink bottles, and oil storage bottles, are becoming increasingly popular in India. Bottles used to package water take over 1,000 years to biodegrade and, if incinerated, contain poisonous gases. Recycling these PET bottles requires more attention however, this was also among the most famous effective ways to minimize waste. Only PET bottles, however, it’s recyclable; all other bottles must be discarded. In fact, only 1 out of 5 containers are able to be sent to the recycle bin. The strength criteria was studied in PET bottles by filled up with different waste materials such as M-sand, Quarry dust, Fly ash, River sand and Construction debris. These filled bottles are inserted in concrete cube mould for minimising the concrete quantity and strength parameters were studied. Based on the experimental work, it was identified that, PET bottles having good compression resistance and also act as a filler material in concrete.

Laboratory Investigation into the Flexural Behavior of Embedded Concrete Sleepers in Two-Stage Concrete with Preplaced Ballast Aggregate

The conversion of ballasted railway tracks into slab tracks using the preplaced aggregate concrete (PAC) technology over the bridges and in the tunnels has been introduced by many researchers but the flexural behavior of this composite system has not yet been studied. Therefore, in the first stage, a series of mortar and concrete mixture designs were proposed and evaluated. Subsequently, a concrete beam mold with dimensions of 3 * 0.6 * 0.5 m, which represented the track conditions, was developed and the bending behavior of the constructed beams in both conditions of the presence and absence of the concert B70 sleeper were investigated. The maximum bending force in the middle of the concrete beam without a sleeper (SE) equaled 177.5 kN. In addition, the average values of bending tolerance by the sleeper including a PAC beam for three specimens in the four modes of the positive moment of midspan (SPM), negative moment of midspan (SNM), positive moment of rail seat (SPR), and negative moment of rail seat (SNR) were 55.25 kN m, 32.5 kN m, 91.84 kN m, and 38.21 kN m, respectively, which met the requirements of the AREMA regulations.

Air Pollution Control by Using Advanced Oxidation Processes (AOPs)

Among air pollution control strategies, air cleaning with Advanced Oxidation Processes (AOPs) has been drawing more and more attention because of the restraints in the production of secondary pollution. AOPs have a wide range of applications such as air (odour elimination, purification), soil (remediation) and water decontamination. Ideally, the photo catalyst, titanium dioxide, is introduced in the top layer of the concrete pavement for best results. In addition, the combination of TiO2 with cement-based products offers some synergistic advantages, as the reaction products can be adsorbed at the surface and subsequently be washed away by rain. The main aim of this research work is to measure the effect of titanium dioxide as photo catalyst in purifying nitrogen oxide (NOX) and Carbon Oxides (COX) on pavement surface and outdoor environment condition. For that, TiO2 is replaced for cement at different proportions of 5%, 10% & 15% in terms of weight in the cement concrete moulds of 10 mm uniform thickness and curing is done for seven days, then same were exposed to the sunlight at Ijoor circle sampling point Rama Nagar Town for 21 days of observation. From the Energy Dispersive Spectroscopy (EDS) analysis, result it is observed that atom percentage increased maximum of 59.05 for carbon atoms for 10% proportion specimen. Then, check the amount of percentage for carbon atoms adsorbed by 10% proportion specimen at police/Kandaya Bhavan circle and Railway station circle sampling points of Rama Nagar Town for 21 days of observations and the results shows that, carbon atom percentage increased maximum of 42.99 and 58.69 for carbon atoms respectively at above sampling points. From this work, it is conclude that the Carbon atoms and Nitrogen atoms present in the atmosphere will be reduce up to some level when replace 10% of Titanium dioxide with cement in the concrete moulds of 10 mm thickness by Photo catalytic activity.

Numerical analysis of thermal cracking estimation of mass concrete with GGBS at an early age

At an early age, the temperature rise in mass concrete is attributable primarily to the propagation of heat due to an exothermic reaction of cementitious materials and water. The temperature variation in the mass concrete between the core and its surfaces results in the development of thermal stresses. It might occur cracking if these stresses surpass the gained tensile strength of concrete. The paper compares experimental and numerical outcomes of heat generation in concrete mould 0.15 m × 0.15 m × 0.15 m in size. Four concrete mixtures with ground granulated blast-furnace slag (GGBS) replacement to cement 0%, 10%, 30%, and 50% were used in the study. Virtual Cement and Concrete Testing Laboratory (VCCTL) software was used for obtaining the degree of hydration and adiabatic temperature of the four mixtures. Finite element modeling of these mixtures observed good agreement with experimental testing captured by the thermometer. Following that, numerical simulation was utilized to study the effect of the block size (cubic models with edge length 0.5 m, 1.0 m, 2.0 m, and 3.0 m) on temperature rise and the associated risk of cracking in mass concrete blocks.