scholarly journals Performance Evaluation of Precast Concrete Using Microwave Heating Form

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1113 ◽  
Author(s):  
Hyeonggil Choi ◽  
Taehoon Koh ◽  
Heesup Choi ◽  
Yukio Hama
Keyword(s):  
Microwave Heating ◽  
Co2 Emissions ◽  
Precast Concrete ◽  
Surface Condition ◽  
Economic Feasibility ◽  
Strength Development ◽  
Excellent Performance ◽  
Steam Curing ◽  
Heat Curing ◽  
Microwave Heat

The purpose of this study is to evaluate the temperature distribution, strength development, porosity, scanning electron microscopy observation, shrinkage, and surface properties of concrete in order to apply microwave heat curing to the precast method and to analyze the CO2 emissions and economic feasibility of microwave heat curing. The heating of a steel form by microwave heating enabled concrete to be efficiently cured at a temperature within a range of ±5 °C. After the curing, demolding strength could be cleared through the densification of the concrete by decreasing the porosity of the concrete. Microwave heat curing exhibited excellent performance compared to conventional steam curing in terms of efficient temperature control, occurrence of cracks due to shrinkage, surface condition of concrete after curing, economic efficiency, and CO2 emissions. However, verification and supplementation based on actual data are necessary so that environments applicable to the various sizes and shapes of forms can be prepared.

scholarly journals Application of the High Early Strength Type Expansive Agent to the Blast Furnace Slag Combination Concrete with GGBFS under Steam Curing

2019 ◽  
Vol 278 ◽  
pp. 01005
Author(s):  
Erica Enzaki ◽  
Takashi Sakuma ◽  
Eizou Takeshita ◽  
Shigeyuki Date
Keyword(s):  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Early Stage ◽  
Precast Concrete ◽  
Curing Temperature ◽  
Strength Development ◽  
Steam Curing ◽  
Expansive Agent ◽  
Early Strength ◽  
Furnace Slag

In recent years, the use of blast furnace slag material is being focused as environmental loading reduction and sustainable construction. However, in general, autogeneours shrinkage of the concrete using much amount of GGBFS is large in compared to normal concrete, therefore risk of cracking should be cared. On the other hand, strength development speed of concrete at early stage will be decreasing as the dosage of GGBFS increases, even under steam curing condition. It can be considered these points will be significant disadvantage in both productivity and quality of precast concrete. So in this study, early strength type expansive agent and setting accelerator were used in combination. As a result, it was confirmed that compressive strength at early stage is obviously increased. And steam curing temperature can be reduced about 10 degrees, and also, 600×10-6 of restraint expansion was obtained.

Effect of Microwave Curing to the Compressive Strength of Fly Ash Based Geopolymer Mortar

2016 ◽  
Vol 841 ◽  
pp. 193-199 ◽  
Author(s):  
Mohd Mustafa Al Bakri Abdullah ◽  
Muhammad Faheem Mohd Tahir ◽  
Kamarudin Hussin ◽  
Mohammed Binhussain ◽  
Januarti Jaya Ekaputri
Keyword(s):  
Global Warming ◽  
Fly Ash ◽  
Precast Concrete ◽  
Construction Materials ◽  
Cost Savings ◽  
Curing Temperature ◽  
Conventional Heating ◽  
Strength Development ◽  
Microwave Curing ◽  
Heat Curing

With the advancement of technology and the economic crisis in Malaysia, has been promoting the development of infrastructure in the use of new structural materials but overall is unsatisfactory in terms of cost savings. One of the alternatives that can be used is to use fly ash as a cement replacement in manufacturing mortar. Replacement of cement with geopolymerization mortar can reduce manufacturing costs and could reduce global warming arising from the production of cement for the production of Portland cement for the release of CO2 into the atmosphere, where CO2 gas gives the largest contribution to global warming . The study will be focused on the effect of microwave curing with various durations and temperature to the mechanical and physical properties of fly ash based geopolymer mortar. For the conventional heating technique, heat is distributed in the specimen from the exterior to the interior leading to the non-uniform and long heating period to attain the required temperature. Application of microwave to the fresh concrete results in removal of water, collapse of capillary pore and densification of sample. Heat curing has been applied to construction materials especially for the precast concrete to improve the strength development process. This concrete attains sufficient strength in short curing time, so the molds can be reused, and the final products can be rapidly delivered to the site. The effect of curing temperature together with their aging days of the cured product will also be investigated. Mechanical properties of the product will be tested using compressive test, and density of the samples.

Effect of chemical admixtures on the sulfate requirement of cement

1980 ◽  
Vol 7 (2) ◽  
pp. 256-263 ◽  
Author(s):  
M. A. Ward ◽  
S. M. Khalil ◽  
B. W. Langan
Keyword(s):  
Portland Cement ◽  
Initial Temperature ◽  
Precast Concrete ◽  
Steam Curing ◽  
Sulfate Content ◽  
Chemical Admixtures ◽  
Cost Of Energy ◽  
Hot Weather ◽  
The Cost ◽  
Ready Mixed Concrete

As the cost of energy and hence the cost of producing Portland cement increase, the question arises as to whether we are obtaining optimum performance from the admixtures we use. As an example, data are presented indicating that a significant improvement in strength and shrinkage can be achieved by optimizing the sulfate content of the cement for given cement–admixture combinations. It is shown that the optimum SO3 is clearly a function of the initial temperature of the concrete, particularly during the first 24 h after casting, a characteristic of considerable importance in hot weather concreting and steam curing of concrete products. It is recommended that more attention be directed towards optimizing the effectiveness of chemical admixtures in both the ready-mixed concrete and precast concrete industries.

scholarly journals Influence of Steam Curing Method on the Performance of Concrete Containing a Large Portion of Mineral Admixtures

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Mengyuan Li ◽  
Qiang Wang ◽  
Jun Yang
Keyword(s):  
Chloride Ion ◽  
Mineral Admixtures ◽  
Strength Development ◽  
Steam Curing ◽  
Chloride Permeability ◽  
Curing Conditions ◽  
Volume Stability ◽  
Ettringite Formation ◽  
The Impact ◽  
Reaction Degree

A comparison was made between the impact of raising the thermostatic temperature and the impact of prolonging the thermostatic time on the performance of steam-cured concrete containing a large portion of fly ash (FA) or ground granulated blast furnace slag (GGBS) by analysing the form removal strength, chemically combined water content, reaction degree, strength development, chloride permeability, and volume stability. For the materials and test conditions reported in this study, raising the thermostatic temperature is more favourable for concrete containing FA, as indicated by the significantly higher form removal strength and the higher growth of reaction degree of FA compared with prolonging the thermostatic time. With an increase in the thermostatic temperature, the hydration degree of a binder containing FA or GGBS initially increases and subsequently decreases. Although concrete containing FA can obtain satisfactory form removal strength with steam curing at 80°C, the late strength development of concrete containing FA is slow for the same curing conditions. The effect of the late performance of resistance to chloride ion permeability improved by FA is better than the effect improved by GGBS. The risk of destroying the structure of concrete containing a large portion of FA or GGBS due to delayed ettringite formation (DEF) is minimal when specimens were steam-cured at 80°C.

Effect of Type of Cement and Expansive Agent on the Hardening of Steam-Cured Concrete

2017 ◽  
Vol 744 ◽  
pp. 105-113 ◽  
Author(s):  
Takayoshi Maruyama ◽  
Hideaki Karasawa ◽  
Shigeyuki Date
Keyword(s):  
Early Stage ◽  
Precast Concrete ◽  
Curing Temperature ◽  
Steam Curing ◽  
Slag Powder ◽  
Expansive Agent ◽  
Cast Concrete ◽  
Increase Productivity ◽  
Early Strength ◽  
Furnace Slag

Pre-cast concrete products are sometimes manufactured in two cycles daily. It is ensured that they have the required strength at an early stage of demolding by increasing the steam curing temperature to reduce cost or increase productivity. However, the reduction in durability because of cracking due to thermal stress is a topic of concern. On the other hand, it has been known that fine blast-furnace-slag powder and expansive agents show high temperature dependence. Although they are used even in precast concrete products, the effect of steam curing on these materials is not known. Thus, in this study, the expression of compressive strength and expansion that are critical in improving the quality and productivity of precast concrete products was investigated, using high early-strength cement and two types of expansive agents, namely, ettringite-based and lime-based agents. Consequently, the strength expression was accelerated by the addition of expansive agent to ordinary cement and high early-strength cement. The extent of restrained expansion is greater for the lime-based expansive agent than for the ettringite-based expansive agent, and when an expansive agent is added to high early-strength cement, the extent of restrained expansion falls to a level lower than that in the case of ordinary cement.

scholarly journals Analysis of CO2 emissions and techno-economic feasibility of an electric commercial vehicle

2017 ◽  
Vol 193 ◽  
pp. 297-307 ◽  
Author(s):  
Eduardo Aparecido Moreira Falcão ◽  
Ana Carolina Rodrigues Teixeira ◽  
José Ricardo Sodré
Keyword(s):  
Co2 Emissions ◽  
Commercial Vehicle ◽  
Economic Feasibility

scholarly journals PEMAKAIAN FLY-ASH SEBAGAI CEMENTITIOUS PADA BETON MUTU TINGGI DENGAN STEAM CURING (THE USE OF FLY-ASH AS CEMENTITIOUS ON HIGH-STRENGTH CONCRETE WITH STEAM CURING)

2014 ◽  
Vol 10 (2) ◽  
Author(s):  
Erwin Rommel ◽  
Yunan Rusdianto
Keyword(s):  
Fly Ash ◽  
Precast Concrete ◽  
Chemical Properties ◽  
High Strength ◽  
Steam Curing ◽  
Initial Strength ◽  
Speed Up ◽  
Physical And Chemical ◽  
And Chemical Properties

Erwin Rommel1 & Yunan Rusdianto2Jurusan Teknik Sipil Fakultas Teknik Universitas Muhammadiyah MalangAlamat Korespondensi :Jalan Raya Tlogomas 246 Malang 65144email : [email protected] HP 08123314432ABSTRACTThe use of fly-ash as cementitious will be made to utilize physical and chemical properties offly-ash that has a dominan of silica and good of modulus fines. The use of steam curing will be donein this study which can speed up the cycle of making concrete. This is advantageous in the productionof precast concrete and velocity field construction.The research was conducted by making concrete cube 15x15x15 cm for 80 pieces and thentested the compressive strength and absorption of concrete. Achieve the quality of concrete madewith the provision of K600 with giving the fly-ash respectively 7.5%, 15% and 30% by weight ofcement.The results of the research obtained by the use of fly-ash as much as 7.5% as a cementitiousthat was given to the steam curing will provide the initial strength of concrete reached 47% ofcompressive strength at 28 days. While the effect of giving fly-ash in concrete has not seen absorptionsignificantly when compared to concrete without fly-ash.Key word : concrete, fly-ash, steam curing

scholarly journals Model-Based Methods to Produce Greener Metakaolin Composite Concrete

2021 ◽  
Vol 11 (22) ◽  
pp. 10704
Author(s):  
Ki-Bong Park ◽  
Run-Sheng Lin ◽  
Yi Han ◽  
Xiao-Yong Wang
Keyword(s):  
Energy Consumption ◽  
Co2 Emissions ◽  
Evaluation Model ◽  
Concrete Strength ◽  
Resource Consumption ◽  
Evaluation Framework ◽  
Strength Development ◽  
Sustainability Evaluation ◽  
Binder Ratio ◽  
Compressive Strength Development

Metakaolin is reactive and is widely used in the modern concrete industry. This study presents an integrated strength–sustainability evaluation framework, which we employed in the context of metakaolin content in concrete. First, a composite hydration model was employed to calculate reactivity of metakaolin and cement. Furthermore, a hydration-based linear equation was designed to evaluate the compressive strength development of metakaolin composite concrete. The coefficients of the strength evaluation model are constants for different mixtures and ages. Second, the sustainability factors—CO2 emissions, resource consumption, and energy consumption—were determined based on concrete mixtures. Moreover, the sustainability factors normalized for unit strength were obtained based on the ratios of total CO2 emissions, energy consumption, and resource consumption to concrete strength. The results of our analysis showed the following: (1) As the metakaolin content increased, the normalized CO2 emissions and resource consumption decreased, and the normalized energy first decreased and then slightly increased. (2) As the concrete aged from 28 days to three months, the normalized CO2 emissions, resource consumption, and energy consumption decreased. (3) As the water/binder ratio decreased, the normalized CO2 emissions, resource consumption, and energy consumption decreased. Summarily, the proposed integrated strength–sustainability evaluation framework is useful for finding greener metakaolin composite concrete.

scholarly journals Mechanical Properties of OPC - Geocement Concrete

2019 ◽  
Vol 8 (4) ◽  
pp. 3733-3736
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Portland Cement ◽  
Ordinary Portland Cement ◽  
External Heat ◽  
Partial Replacement ◽  
Strength Development ◽  
Strength Increase ◽  
Heat Curing ◽  
Compressive Strength Development

Nowadays geopolymer concretes are subjected to heat curing. A large amount of highly corrosive and the hygroscopic alkaline activators are nowadays generally utilized in producing geopolymer concretes. In this paper, hybrid Ordinary Portland Cement (OPC) and geopolymer mixes are developed. The mainly used activator id the Solid potassium carbonate at different percentage is used as 5% & 10% of the weight of geopolymeric materials and OPC was blended with geopolymeric materials in different proportions. By adding cement, improves all the geopolymer properties except workability. By Applying external heat, it plays an important role in gaining strength. Strength gained by the absence of external heat is achieved by using Portland cement as a partial replacement of geocement. The influence of OPC content on the compressive strength development is investigated, and the optimized amount of solid activator to be used in the mix is also investigated. It is observed that percentage of strength increase decreases from52.24% to 14.77% as the OPC content increased from 20% to 60%.

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