scholarly journals Effects of Shrinkage Reducing Agent and Expanded Cement on UHPC Fluidity, Mechanical Properties, and Shrinkage Performance

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Tingyu Wang ◽  
Jianqing Gong ◽  
Bo Chen ◽  
Xiao Gong ◽  
Hongkui Luo ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Setting Time ◽  
Autogenous Shrinkage ◽  
Drying Shrinkage ◽  
Reducing Agent ◽  
Strength Development ◽  
Study Results ◽  
Binder Ratio ◽  
Early Strength ◽  
Shrinkage Reducing Agent

The purpose of this study was to evaluate the effects of a shrinkage reducing agent (SRA) and Portland expanded cement (PEC) on the fluidity, mechanical properties, and shrinkage performance of ultrahigh-performance concrete (UHPC). The results indicated that the fluidity of the fresh UHPC mortar initially decreased and then increases along as a function of SRA dosage. When the dosage of SRA was 1%, the UHPC mortar fluidity was at its minimum. For dosages exceeding 1%, the additional water-binder ratio of the mortar increased, which in turn increased the UHPC fluidity. That is, the SRA delayed the cement hydration and increased the setting time, which is not conducive for early strength development of UHPC. As the SRA dosage was increased (i.e., 0%–2%), the autogenous shrinkage of UHPC decreased significantly such that even a small dosage of about 0.5% SRA was able to effectively reduce drying shrinkage. From the study results, it was also observed that PEC accelerated the loss of fluidity in the fresh UHPC and concurrently promoted the early strength development of UHPC. At 75% PEC content, the strength enhancement effects tended to be stable. This means that although the addition of PEC will potentially increase the autogenous shrinkage of UHPC, it has the positive effect of inhibiting drying shrinkage provided that the PEC dosage is controlled within the 25%–50% range. Furthermore, morphological analyses using a scanning electron microscope (SEM) indicated that an increase in the SRA dosage loosens the UHPC microstructure, with the formation of the hydration products remaining incomplete, thus ultimately causing the UHPC strength to decrease. Overall, the study findings indicated that 2% SRA and 25%–50% PEC can effectively reduce the shrinkage of UHPC and are, therefore, recommended as the optimum dosages.

scholarly journals Effects of Shrinkage Reducing Agent and Expansive Admixture on the Volume Deformation of Ultrahigh Performance Concrete

2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Su Anshuang ◽  
Qin Ling ◽  
Zhang Shoujie ◽  
Zhang Jiayang ◽  
Li Zhaoyu
Keyword(s):  
Compressive Strength ◽  
Autogenous Shrinkage ◽  
Drying Shrinkage ◽  
Reducing Agent ◽  
Cementitious Material ◽  
Volume Deformation ◽  
Air Content ◽  
Expansive Agent ◽  
Reduction Effect ◽  
Shrinkage Reducing Agent

This paper investigated the influences of shrinkage reducing agent and expansive admixture on autogenous and drying shrinkage of ultrahigh performance concrete (UHPC) containing antifoaming admixture. The shrinkage reducing agent was used at dosage of 0.5%, 1%, and 2% and the expansive admixture was used at dosage of 2% to 4% by mass of cementitious material. The results show that the air content of UHPC increases with the higher addition of shrinkage reducing agent and expansive admixtures. However, the fluidity, compressive strength, and shrinkage of UHPC exhibit a declining tendency. The usage of expansive agent at dosage of 4% significantly reduces the shrinkage of UHPC. The 7-day autogenous shrinkage was decreased by 16.0% and 28-day drying shrinkage was decreased by 29.5%, respectively. Shrinkage reducing agent at dosage of 2% reduced the 7-day autogenous shrinkage by 44.3% and 28-day drying shrinkage by 50.2%. Compared with expansive admixture, shrinkage reducing agent exhibits more efficient shrinkage reduction effect on UHPC.

scholarly journals Development and Performance Assessment of the High-Performance Shrinkage Reducing Agent for Concrete

2016 ◽  
Vol 2016 ◽  
pp. 1-8
Author(s):  
Hyung Sub Han ◽  
Jong Kyu Kim ◽  
Yong Wook Jung
Keyword(s):  
Compressive Strength ◽  
High Performance ◽  
Drying Shrinkage ◽  
Reducing Agent ◽  
Optimal Amount ◽  
Air Content ◽  
Early Strength ◽  
And Performance ◽  
Shrinkage Reducing Agent ◽  
Strength Improvement

To develop a high-performance shrinkage reducing agent, this study investigated several shrinkage reducing materials and supplements for those materials. Fluidity and air content were satisfactory for the various shrinkage reducing materials. The decrease in viscosity was the lowest for glycol-based materials. The decrease in drying shrinkage was most prominent for mixtures containing glycol-based materials. In particular, mixtures containing G2 achieved a 40% decrease in the amount of drying shrinkage. Most shrinkage reducing materials had weaker level of compressive strength than that of the plain mixture. When 3% triethanolamine was used for early strength improvement, the strength was enhanced by 158% compared to that of the plain mixture on day 1; enhancement values were 135% on day 7 and 113% on day 28. To assess the performance of the developed high-performance shrinkage reducing agent and to determine the optimal amount, 2.0% shrinkage reducing agent was set as 40% of the value of the plain mixture. While the effect was more prominent at higher amounts, to prevent deterioration of the compressive strength and the other physical properties, the recommended amount is less than 2.0%.

scholarly journals Durable High Early Strength Concrete via Internal Curing Approach using Saturated Lightweight and Recycled Concrete Aggregates

2020 ◽  
Vol 2674 (7) ◽  
pp. 67-76
Author(s):  
Faisal Qadri ◽  
Christopher Jones
Keyword(s):  
Cement Content ◽  
Autogenous Shrinkage ◽  
Drying Shrinkage ◽  
Recycled Concrete ◽  
Internal Curing ◽  
Strength Development ◽  
Freeze Thaw ◽  
Strength Concrete ◽  
Repair Materials ◽  
Early Strength

Concrete pavements tend to degrade at joints when concrete gets exposed to freeze-thaw cycles in the presence of moisture. In Kansas, U.S., one common repair method for deteriorated concrete pavement involves patching with high early strength concrete (HESC). For heavily trafficked routes and intersections, this is often done at night, so that the pavement can be opened to traffic next morning. Often, patched concrete shows poor durability lasting for just few years. HESC mixtures often include high cement content and low water-to-cement ratio. These factors lead to shrinkage that creates cracks which, in turn, facilitate the ingress of detrimental substances that eventually degrade patches. Internal curing (IC) has been explored in this study to improve the durability of HESC repair materials. Saturated lightweight aggregates and recycled crushed concrete were used to replace a portion of the virgin fine aggregates. Both mixtures were compared with a control mixture. These three mixtures were replicated for low and high cement contents. The test program focused on assessing two main performance indicators—strength development and durability. Durability testing included autogenous and drying shrinkage, and freeze-thaw cycling where relative dynamic modulus of elasticity, expansion, and mass change were measured. Target strengths were achieved in all mixtures. Autogenous shrinkage test results showed that IC significantly improves shrinkage potential and durability. For these mixtures, low cement content also appears to improve durability.

scholarly journals Comparison of calculation models’ estimates with actual measured autogenous shrinkage in High-Performance Cement Composites

2018 ◽  
Vol 219 ◽  
pp. 03009
Author(s):  
Adam Zieliński ◽  
Karol Federowicz ◽  
Maria Kaszyńska
Keyword(s):  
High Performance ◽  
Setting Time ◽  
Autogenous Shrinkage ◽  
Drying Shrinkage ◽  
Cement Composites ◽  
Total Deformation ◽  
Binder Ratio ◽  
Compressive Strength Of Concrete ◽  
Spanish Model ◽  
Calculation Models

There are several calculation models for estimation of shrinkage in concrete. The most popular ones are: ACI-209R-92 method, Bažant-Baweja model (B3), Gardner’a-Lockman’a model (GL 2000), CEB-FIP (CEB MC90-99), Spanish model (EHE), EuroCode method (EC-2) from 2004 and Tazawa–Miyazawa model (JSCE). Majority of aforementioned models do not include the deformation caused by the autogenous shrinkage. The methods assume the total deformation as a result of drying shrinkage action. Additionally, a non-standard method was proposed by Jonasson and Hedlund. However it only is used to determine the autogenous shrinkage of High-Performance Concretes (HPC). Tazawa-Miyazawa model and Jonasson-Hedlund method are based on the proportions and material properties such as water/cement ratio, water/binder ratio, type of the cement, or start of setting time. In contrary, the CEB MC90-99 and EC-2 models correlate the autogenous shrinkage with the overall compressive strength of concrete. The article presents the analysis of various calculation models in comparison to actual measurements. The autogenous shrinkage was measured in four cement composites starting at casting up till 28 days of curing.

scholarly journals Effects of the alkaline solution/binder ratio and curing condition on the mechanical properties of alkali-activated fly ash mortars

2017 ◽  
Vol 24 (5) ◽  
pp. 773-782
Author(s):  
Maochieh Chi
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Fly Ash ◽  
Alkaline Solution ◽  
Drying Shrinkage ◽  
Strength Development ◽  
Initial Surface ◽  
Binder Ratio ◽  
Curing Condition ◽  
Alkali Activated

AbstractThe study investigates the effects of the alkaline solution/binder ratio and the curing condition on the mechanical properties of alkali-activated fly ash (AAFA) mortars. Class F fly ash was used as the raw material, and sodium hydroxide and liquid sodium silicate were used for the preparation of alkaline activators. Three alkaline solution-to-binder ratios (0.35, 0.5, and 0.65) and four different initial curing conditions (curing in air at ambient temperature for 24 h, 30°C for 24 h, 65°C for 12 h, and 85°C for 6 h) were considered. Test results show that AAFA mortars with alkaline solution-to-binder ratio of 0.35 had higher compressive strength, lower drying shrinkage, lower water absorption, and lower initial surface absorption rate than the other mortars. Furthermore, the curing condition influenced the compressive strength development and drying shrinkage of AAFA mortars at early ages. AAFA mortars cured at 65°C for 12 h appeared to have superior mechanical properties. XRD demonstrates that the hydration products of AAFA mortars are mainly amorphous alkaline aluminosilicate gel, which attributed to the compressive strength. Consequently, the alkaline solution-to-binder ratio significantly affects more the mechanical properties than the curing condition based on the presented results.

scholarly journals One-Part Plastic Formable Inorganic Coating Obtain from Alkali-Activated Slag /Starch(CMS) Hybrid Composites

Molecules ◽  
2020 ◽  
Vol 25 (4) ◽  
pp. 844 ◽  
Author(s):  
Xuesen Lv ◽  
Yao Qin ◽  
Zhaoxu Lin ◽  
Zhenkun Tian ◽  
Xuemin Cui
Keyword(s):  
Adhesive Strength ◽  
Hybrid Composites ◽  
Setting Time ◽  
Drying Shrinkage ◽  
Plastic Viscosity ◽  
Strength Development ◽  
Cracking Behavior ◽  
Study Results ◽  
Inorganic Coating ◽  
Alkali Activated

Coating technology can be applied to decorate building constructions. Alkali-activated materials (AAM) are promising green and durable inorganic binders which show potential for development as innovative coating. In the paper, the possibility of using AAM composited with starch (CMS) as a novel plastic formable inorganic coating for decorating in building was investigated. The rheological properties, including plastic viscosity, yield stress, and thixotropy were considered to be critical properties to obtain the working requirements. Four different mixtures were systematically investigated to obtain the optimum formulation, and then were used to study their hardened properties, such as mechanical strengths (compressive, flexural, and adhesive strength), drying shrinkage, cracking behavior, and microstructure. Study results found that CMS could quickly and efficiently be hydrolyzed in an alkaline solution to produce organic plastic gel which filled in AAM paste, leading to the significant improvement of coating consistency, plastic viscosity, and thixotropy. The optimum coating composited with 15.40 wt% CMS shows a relatively stable rheological development, the setting time sufficient at higher than 4 h. Furthermore, CMS shows a significant positive effect on the cracking and shrinkage control due to padding effect and water retention of CMS, which results in no visible cracks on the coating surface. Although the mechanical strength development is relatively lower than that of plain AAM, its value, adhesive strength 2.11 MPa, compressive strength 55.09 MPa, and flexural strength 8.06 MPa highly meet the requirements of a relevant standard.

Effect of Expansive Additive and Shrinkage Reducing Agent on Plastic Shrinkage of Steam-Cured Mortar

2018 ◽  
Vol 936 ◽  
pp. 207-213
Author(s):  
Sarapon Treesuwan ◽  
Komsan Maleesee ◽  
Shigeyuki Date
Keyword(s):  
Factorial Design ◽  
Setting Time ◽  
High Volume ◽  
Reducing Agent ◽  
Steam Curing ◽  
Initial Setting Time ◽  
Plastic Shrinkage ◽  
Initial Setting ◽  
Expansive Additive ◽  
Shrinkage Reducing Agent

This research is part of the mortar’s plastic shrinkage study. Contents in this article is related to how the Expansive Additive (EX), Shrinkage Reducing Agent (SRA), and Fly Ash (FA) help to reduce and control the shrinkage and to compare the effectiveness of these substances used in the normal curing, i.e., at 30 °C and in the steam curing process by using the factorial design with 3 factors and to be divided into 2 levels. Factors to be studied are the amount of EX, SRA and FA replacement. The test of plastic shrinkage was conducted in accordance with the ASTM C1579-06 standard, placing the strain gauge 0.5 centimeters beneath the surface in the middle of the mold, recording the shrinkage rate starting from the initial setting time for 24 hours. The results showed that, in normal curing, the EX influences the expansion while, in steam curing, the EX and SRA significantly influences the expansion. To add the FA in high volume along with the EX significantly effects the expansion for both the normal and steam curing. Furthermore, the study model and equation for plastic shrinkage of mortar are presented in the form of factor proportion to be considered from the factorial design study basis.

scholarly journals Effects of Shrinkage Reducing Agent and Expansive Additive on Plastic Shrinkage of Mortar at Different Temperatures

2018 ◽  
Vol 206 ◽  
pp. 02002
Author(s):  
Sarapon Treesuwan ◽  
Komsan Maleesee ◽  
Shigeyuki Date
Keyword(s):  
High Temperature ◽  
Setting Time ◽  
Reducing Agent ◽  
Early Age ◽  
Initial Setting Time ◽  
Plastic Shrinkage ◽  
Different Temperatures ◽  
Expansive Additive ◽  
Hot Weather ◽  
Shrinkage Reducing Agent

In the construction, it is inevitable to perform plaster work in hot weather which causes the dehydration and rapid shrinkage on the paste during the early age. This research shows the studies of reducing the plastic shrinkage of mortar during the early age with such additives as the Shrinkage Reducing Agent (SRA), the Expansive Additive (EX), and the Fly Ash (FA) in controlled temperatures at 30°C and 40°C, with relative humidity between 60% and 70% according to the ASTM C1579-06 standard, with the strain gauge installed at 0.5 cm.from the surface. The shrinkage rate was measured starting from the Initial Setting Time and every 10 minutes afterwards for 24 hours. The results show that high temperature effects the cracking and how to use different formulas of additive under different circumstances is considerably important. To use only one additive is not sufficient in high temperature. To use the SRA in addition to the EX enhances better expansion than to use only the EX. Moreover, it is recommended to pay close attention in adding large amount of the FA into mortar with the EX and SRA added which extremely enhances the expansion and potential cracking.

Improving the Durability of High Early Strength (HES) Concrete Patching Materials for Concrete Pavements

2020 ◽  
Vol 2674 (8) ◽  
pp. 12-23
Author(s):  
Cameron Wilson ◽  
W. Jason Weiss
Keyword(s):  
Cement Content ◽  
Autogenous Shrinkage ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Strength Development ◽  
Concrete Pavements ◽  
Shrinkage Cracking ◽  
Concrete Mixtures ◽  
Water To Cement Ratio ◽  
Early Strength

High early strength (HES) concrete patching materials are increasingly used to repair damaged pavements. The use of HES concrete enables the repaired pavement to be opened to traffic shortly after the repair has been installed; for example, opening pavements to traffic 4–6 h after the concrete is placed is becoming more common. HES concrete mixtures are typically designed with a low water-to-cement ratio and a high cement content; they contain accelerating admixtures and limited supplementary cementitious materials. As a result, these HES patches may be susceptible to self-desiccation, causing autogenous shrinkage and early age cracking. Self-desiccation can lead to reduced hydration, limited strength gain, and overestimation of strength development in maturity-based predictions. The objectives of this study are threefold. First, the paper will illustrate how self-desiccation can lead to the premature cessation of hydration and increased potential for shrinkage cracking. Second, the paper will illustrate how maturity-based predictions can be modified to account for self-desiccation. Third, internal curing is discussed as a way to mitigate self-desiccation and shrinkage ultimately improving the performance of HES concrete patching materials.

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