Creep and shrinkage of ecological self consolidating concrete

Optimizing concrete mixtures with regard to replace a part of cement content with supplementary cementitious materials can prompt the design of ecological-self consolidating concrete. By replacing more than 60% of cement with residual product from other industries such as Fly Ash, Micro Silica, and lime, the energy consumption and CO2 emission of concrete are reduced. This study was performed to monitor the creep and shrinkage of high volume supplementary cementitious material of self consolidating concrete (HVSCM-SCC) and ensure desired performance of concrete. Total sixteen and Twenty Four specimens from different concrete mixtures with different replacement level (up to 75% of cement replacement) were monitored for creep and shrinkage respectively. Moist and accelerated curing regimes were utilized in this study to see the effect of accelerated curing on creep and shrinkage of HVSCM-SCC. Mechanical properties of different age 1,3,7,28,56 and 90 days were conducted. Experiments have shown that 75% level replacement of cement experienced low creep and shrinkage rate than other mixtures. The creep and shrinkage values of HVSCM-SCC were compared to prediction models proposal by AASHTO LRFD (2007), ACI-209R (2009), and AS 3600 (2009) to ensure the validity of these models for HVSCM-SCC

Time-Dependent Prestress Loss Behavior of Girders in Missouri Bridge A7957 Compared with a U.S. Data Set of High-Performance Concrete Bridge Girders

In this study, six precast, prestressed concrete girders were constructed and instrumented to measure prestress losses of bridge A7957 in Missouri. The concrete mixture for the bridge was designed with varying mechanical and rheological properties. High-strength concrete, high-strength self-consolidating concrete, and normal-strength self-consolidating concrete were used to construct the bridge girders. Vibrating wire strain gauges with integrated thermistors were embedded through the girders\u27 cross sections to measure strains and temperatures. The measured short- and long-term prestress losses were compared with those obtained using different empirical models, specified in the AASHTO LRFD Bridge Design Specifications and in the PCI Design Handbook: Precast and Prestressed Concrete. This study also presents a comparison of measured prestress losses with data reported in the literature for different concrete types

Performance Study of Ecological Self-Consolidating Cement Mixtures

This study presents a useful analytical method based on a statistical approach for optimizing the performance of Eco-selfconsolidating cement mixture (SCCM) (mortar component). Eco-SCCM is a new class of concrete mixtures that satisfies engineering design requirements (mechanical and rheological properties) and environmental concerns. Three different phases with a total of 43 mixtures were generated using commercially available software to study the effect of using high-volume fly ash on the performance of cement mixtures. Hydrated lime was added as the third component to increase the hydration activity of fly ash. Two different curing regimes were investigated. Fresh properties were measured, and hardened properties such as compressive strength, drying shrinkage, and surface resistivity were also monitored. The results of the phases were compared to track the effect of supplemental levels of fly ash and hydrated lime. To optimize the performance of Eco-SCCM, the desirability function approach was successfully applied. Results showed that mixtures with 37% portland cement Type I/II and 63% fly ash under a moist curing regime yielded the highest performance level

Shear Behavior of Full-Scale High Volume Fly Ash-Self Consolidating Concrete (HVFA-SCC) Beams

An experimental test was carried out to investigate the shear behavior of full-scale beams constructed with high volume fly ash self-consolidating concrete (HVFA-SCC). HVFA-SCC is a new concrete grade of HVFA concrete with the rheology of self-consolidating concrete that satisfies the quality of construction work, environment aspects, and concrete sustainability. Mixes with different cement replacement levels of fly ash and hydrated lime [50%, 60%, and 70% (by weight)] were used. Twelve full-scale reinforced concrete beams were cast and tested using a four-point load test setup. This study focused on observing the effect of factors such as cement replacement level, longitudinal reinforcement ratio, and shear reinforcement ratio on the beam shear behavior. All beams were 4000 mm (13 ft) in length, 457 mm (18 in.) in thickness, and 305 mm (12 in.) in width. Rheological and mechanical properties of the mixes were monitored. During testing, cracking and ultimate shear, deflection, crack pattern, and mode of failure were recorded. Furthermore, test results were compared to conventional concrete study, finite element modeling, and database of conventional concrete and self-consolidating concrete

Fracture Behavior of High Volume Fly Ash-Self Consolidating Concrete

Concrete sustainability can be improved by substituting recycled material for conventional material products. Incorporating fly Ash in a concrete mix design supports cement and concrete producers in reducing the greenhouse gas emission associated with manufacturing cement and concrete. This study was conducted to develop a new cementitious material using high volume fly Ash content. A replacement of more than 50% was utilized to achieve sustainable design and significantly reduce a myriad of environmental impacts. Fracture energy of high volume fly ash–self consolidating concrete (HVFA-SCC) was examined. For this purpose, four mixes with 0%, 50%, 60%, and 70% fly Ash as cement replacements were studied. Hydrated lime was incorporated in the mixture to enhance the hydration process of the fly ash. In all, 16 fracture notched beams were investigated under three –point bending test. The rheological and mechanical properties of the HVFA-SCC were measured and evaluated. Furthermore, a comparison of the fracture energy provisions of different design codes and data reported in the literature was made

Bond performance of high-volume fly ash self-consolidating concrete in full-scale beams

This paper presents an experimental study on bond behavior between steel reinforcement and high-volume fly ash selfconsolidating concrete (HVFA-SCC). HVFA-SCC is a new concrete grade of HVFA concrete with the rheology of self-consolidating concrete that satisfies the quality of construction work, environment aspects, and concrete sustainability. Mixtures with different cement replacement levels of fly ash and hydrated lime (50%, 60%, and 70% [by weight]) were used. Twelve full-scale reinforced concrete beams were cast and tested using a four-point load test setup. This study focused on observing the effect of factors such as cement replacement level, confinement conditions, and casting position on the beam flexural behavior. All beams were 10 ft (3048 mm) in length, 18 in. (457 mm) in thickness, and 12 in. (305 mm) in width. Rheological and mechanical properties of the mixtures were monitored. During testing, cracking and ultimate load, deflection, crack pattern, and mode of failure were recorded. Furthermore, test results were compared to a database of different concrete types such as conventional concrete and self-consolidating concrete. The findings of this study show that HVFA-SCC mixture with 70% replacement is not only feasible in terms of acceptable bond behavior, but also is superior in other certain attributes

Optimization Performance of High Volume Fly Ash Self-Consolidating Mixtures with Hydrated Lime (Mortar Component)

As is known, more sustainable concrete has become the desired aim of many transportation departments. To produce more sustainable concrete, the emphasis has been placed on replacing cement with more sustainable materials and taken into account, materials cost and CO2 footprint. High volume fly ash with hydrated lime mixtures have been proposed as one potential approach for achieving durable and sustainable concrete. In this first phase study, performance ranking analysis approach is presented to optimize the performance of high volume fly ash mortars. A total of 15 mortar mixtures were prepared at different replacement levels (up to 75 percent). Hydrated lime was incorporated with ASTM Class C fly ash to increase hydration reaction at different dosage levels (between 0-15 percentages). Fresh properties and semi Adiabatic temperature tests were conducted for each mixture. Compressive strength, drying shrinkage, bulk electric conductivity, and electric resistivity (surface) were measured and monitored until the age of 90 days. Cost efficiency was also evaluated. Based on performance ranking approach, five different binder compositions were selected to conduct the second phase of this study

Effect of Accelerated Curing on Abrasion of High Volume Supplementary Cementitious Material Self Consolidating Concrete

Sustainability of precast/prestressed concrete plant can be promoted by using supplementary cementitious material and that significantly reduces the embodied energy of precast/prestressed concrete products. Usually, up to 25% of the cement can be replaced with supplementary cementitious materials (SCM). Increasing the level of replacement to exceed 25% is considered to be High-Volume SCM. Appropriate testing should be conducted to ensure desired performance of the concrete. This context reports the results of an experimental investigation of effect of accelerated curing on abrasion resistance of High Volume Supplementary Cementitious Material - Self Consolidating Concrete (HVSCM-SCC). Different mixes proportion with supplementary cementitious materials such as Fly Ash, Micro Silica, and lime (Up to 75% of cement replacement) were tested. Rheological properties of the HVSCM-SCC were measured. Mechanical properties at different ages 1, 3, 7, 28, 56, and 90 days were monitored. To investigate the abrasion resistance, 12 x 12 x 3.5 in specimens at age of 28, 56, and 90 days were conducted. The results of abrasion resistance of HVSCM-SCC were compared to the same mixes cured in the moist room. The result showed that the accelerated curing has a significant influence on abrasion resistance of concrete at early ages

Effectiveness of using Carbon Fiber Grid Systems in Reinforced Two-Way Concrete Slab System

Fiber-reinforced polymers (FRPs) were recently used as a replacing reinforcement in concrete structures in view of their excellent resistance to corrosion, light weight, and high specific strength. A state of the art process of using carbon fiber grids as an internal reinforcement with self-consolidating concrete in two-way slab systems is presented herein. The experimental work included studying the flexural performance of the carbon fiber-reinforced polymers\u27 (CFRP) grid in comparison with the conventional welded steel wire mesh. This study is expected to find its application in parking garages or flooring panels to enhance the durability performance and extend the service life of concrete slab members. The load-deflection relationship, ultimate load, energy absorption, and failure mode of simply supported slabs with different aspect ratios were discussed. The experimental results of this study showed that the fiber-reinforced polymer (FRP) grid is appropriate as a structural reinforcement. In addition, the FRP grid tended to fall within the criteria of minimum load requirements per ASCE 7 as the steel wire reinforcement did and satisfied the service limit state of deflection per ACI 318 at approximately 50% of their ultimate loads

Effect of Accelerated Curing Regimes on High Volume Fly Ash Mixtures in Precast Manufacturing Plants

Fly ash is becoming a common replacement for cement in concrete. Not only does it reduce CO2 emissions, but it is cost effective and often times improves various fresh and hardened properties of concrete. Currently, Fly ash isn\u27t replaced in percentages greater than 25-35% in structural applications because of the delayed concrete setting time. This study presents an experimental investigation to evaluate the performance of mortar mixtures incorporating up to 70% cement replacement with Fly ash under the effect of accelerated curing. Different accelerated curing regimes were investigated in terms of the preset time, curing temperature, and curing time. Fresh and hardened properties of HVFA mortar mixtures were obtained for three replacement level and their results were compared at different ages. The accelerated curing regimes successfully developed high early-age strength mixtures that can be used in the precast industry. Some curing regimes revealed the ability to reduce energy as well as curing time