scholarly journals Research on Properties of High-Performance Cement Mortar for Semiflexible Pavement

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Yazhen Sun ◽  
Yuanyuan Cheng ◽  
Min Ding ◽  
Xuezhong Yuan ◽  
Jinchang Wang
Keyword(s):  
High Performance ◽  
Cement Mortar ◽  
Drying Shrinkage ◽  
Pavement Performance ◽  
Strength Development ◽  
Working Ability ◽  
Pavement Materials ◽  
Optimum Formulation ◽  
Different Types ◽  
Early Strength

Cement mortar is one of the most important components of semiflexible pavement materials; however, the effects of cement mortar formulation on the performance and the grouting rate are rarely studied. Therefore, the optimum formulation of high-performance cement mortar (HPCM) for different types and contents was studied, and the grouting effect of the cement mortar was studied by rutting tests. The results show that polycarboxylate superplasticizer, expansion admixture, and accelerating admixture have different influences on the workability, the strength, and the drying shrinkage of HPCM, and the working ability of HPCM is good by adding these three admixtures. The strength at 7 days is 1.3 to 4 times that of the existing specifications, and the shrinkage rate is less than 0.2. The HPCM has higher early strength, and the strength development is stable in the later period compared with the other research studies. The semiflexible material has better pavement performance when the grouting rate is greater than 90%.

A Study on the Development Mechanism of Early Strength in Cement Mortar Using an Early-Strength Polycarboxylated Agent

2007 ◽  
Vol 348-349 ◽  
pp. 473-476
Author(s):  
Won Jun Park ◽  
Han Seung Lee ◽  
Ki Bong Park
Keyword(s):  
Compressive Strength ◽  
High Performance ◽  
Cement Mortar ◽  
Early Age ◽  
Hydration Products ◽  
Degree Of Hydration ◽  
Exact Analysis ◽  
Mortar Strength ◽  
Early Strength ◽  
Micro Structures

It is well known that PC (polycarboxylate) agent is superior to other agents for the early-strength of concrete. Thus, this study investigates the development of mortar strength using various agents. To prove this, various factors were tested. Furthermore, this study measured compressive strength at the age of 18, 24, 36, 72, and 168 hours and gave a request text TG/DTA to observe minute structures. In addition, this study took pictures of minute structures using an SEM for each agent at the same age. According to the results, mortar using an early-strength PC agents is faster than a general water reducing AE agent, high performance PC agents, and other agents in the acceleration of hydration at the same early age. A TG/DTA test shows that the early-strength PC agents create more hydration products, such as Ca(OH)2, than others at the same age. The degree of pH in each agent is unrelated to the degree of hydration in mortar. An MIP analysis confirms these results. However, other methods are required the exact analysis of micro structures.

Properties of Phosphate Cement Mortar Used as Rapid-Repair Material

2011 ◽  
Vol 250-253 ◽  
pp. 1752-1756 ◽  
Author(s):  
Hong Wei Deng ◽  
Ying Zi Yang ◽  
Xiao Jian Gao
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
No Reduction ◽  
Cement Mortar ◽  
Magnesium Phosphate ◽  
Strength Development ◽  
Repair Material ◽  
Rapid Repair ◽  
Repair Materials ◽  
Early Strength

In order to determine the optimal proportion of magnesium phosphate cement mortar, the influences of ratio of magnesium phosphate cement-based binder (MPB) to sand (MPB/S), effects of fly ash on fluidity and strength development of MPB mortar, and the compatibility between MPB and traditional concrete and shrinkage of MPB mortar were investigated in this paper. The optimal proportion in this test was: setting adjusting agent of 12%, P/M ratio of 1:2(in weight), MPB/S ratio of 1:1 and FA/S ratio of 15%. The results showed that the MPB mortar met the higher early strength requirement of rapid-repair materials, with compressive strength beyond 50MPa and flexural strength more than 9.1MPa at 3 hours, and at later ages no reduction of strength happened. There was a good compatibility between MPB and traditional concrete. The shrinkage of MPB mortar at 28 days was less than 2.89 × 10-4. Therefore MPB is very suitable for rapid repairing of concrete structures.

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.

Strength and Durability of High Performance Road Concrete Containing Ultra-Fine Fly Ash

2011 ◽  
Vol 99-100 ◽  
pp. 1264-1268
Author(s):  
Yi Jin Li ◽  
Yun Li Gong ◽  
Jian Yin
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
High Performance ◽  
Drying Shrinkage ◽  
Strength Development ◽  
Hydraulic Pressure ◽  
Rapid Freezing ◽  
Freezing And Thawing ◽  
Wear Resistant ◽  
Binder Material

This paper presents the influence of ultra-fine fly ash on the strength development and durability characteristics of high performance road concrete. The durability of high performance road concrete is investigated including the permeation resistance under hydraulic pressure, the resistance to rapid freezing and thawing, the wear resistant ability and drying shrinkage. Results on compressive strength and strength development of high performance road concrete are also obtained with the main variables being the partial replacements of cement by ultra-fine fly ash of 20%, 30% and 40% by weight of binder material and the binder material of 360kg/m3 and 400 kg/m3. The test results indicate that the use of ultra-fine fly ash as cement replacement leads to a significant improvement of high performance road concrete resistance to permeation and rapid freezing and thawing. The later compressive strength of concrete containing ultra-fine fly ash is also found to be significantly higher than that of control concrete. The wear resistant ability of high performance road concrete is significantly higher than that of control concrete with similar workability. The high performance road concrete also shows the lower drying shrinkage.

scholarly journals Effect of Sulphur-Containing Tailings Content and Curing Temperature on the Properties of M32.5 Cement Mortar

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5751
Author(s):  
Qian Chen ◽  
Haiming Chen ◽  
Pengju Wang ◽  
Xiang Chen ◽  
Jie Chen
Keyword(s):  
Compressive Strength ◽  
Substitution Rate ◽  
High Speed ◽  
Cement Mortar ◽  
Curing Temperature ◽  
Strength Development ◽  
Hydration Reaction ◽  
Replacement Ratio ◽  
River Sand ◽  
Early Strength

The effect of the dosage of sulphur-containing tailings (STs) and curing temperature on the properties of M32.5 cement mortar was studied in this work. An experimental study was conducted to evaluate the effects of STs with different substitution ratios (0, 10%, 20%, 30%, 40%) on the compressive strength experiment, fluidity, expansion ratio, and pore structure of M32.5 cement mortar. The results showed that the addition of STs reduced the fluidity of mortar, and the fluidity decreased with the increase of the STs dosage. The compressive strength of mortars increased at a lower substitution rate (0~20%) but decreased at a higher substitution rate (>20%). Ettringite peaks and new sulfate peaks were found by X-ray diffraction (XRD) analysis. Scanning electron microscope (SEM) observation of the microstructure showed that a large number of hydrated products, such as ettringite, formed and filled in the interstitial space, which was conducive to the development of strength. The optimal STs replacement ratio of river sand was 10%. Then, the performance of mortar at curing temperatures of 23 ± 1, 40, 60, and 80 °C was further investigated under the optimal STs replacement ratio. Under high-temperature curing conditions, the early strength of M32.5 cement mortar with STs increased greatly, but the late strength decreased gradually with the increase in curing temperature. The early strength development of the mortar mainly depended on the high speed of hydration reaction, and the late strength variation was mainly affected by hydration products and the pore size distribution. After comprehensive consideration, the optimal curing temperature of M32.5 cement mortar with STs was 40 °C.

scholarly journals Factors Influencing the Hydration, Dimensional Stability, and Strength Development of the OPC-CSA-Anhydrite Ternary System

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7001
Author(s):  
Zhenzhen Yang ◽  
Hansong Ye ◽  
Qiang Yuan ◽  
Baiyun Li ◽  
Yuelin Li ◽  
...  
Keyword(s):  
Dimensional Stability ◽  
Drying Shrinkage ◽  
Ternary Systems ◽  
Main Peak ◽  
Strength Development ◽  
Hydration Reaction ◽  
Property Development ◽  
Performance Requirements ◽  
Acceleration Period ◽  
Early Strength

Due to the advantages of high early strength and rapid setting, ternary systems consisting of ordinary Portland clinker (OPC), calcium sulphoaluminate (CSA) clinker, and anhydrite have broad application prospects. However, further studies need to be undertaken to find a more optimal mixing proportion of this ternary binder in order to meet basic performance requirements. In this paper, isothermal calorimetric tests, chemical shrinkage tests, drying shrinkage tests, and compressive strength tests were carried out to systematically identify the effect of the OPC/CSA ratio and anhydrite dosage on the hydration, mechanical property development, and dimensional stability of ternary binders. It was found that a higher CSA content leads to a higher cumulative hydration heat, a shorter acceleration period, and a delayed induction period, which can be ascribed to the retardation of C3S at a high aluminate concentration. However, a higher addition of anhydrite can retard the main peak of hydration despite promoting the intermediate peak and improving the hydration reaction rate. The drying shrinkage of blends decreases first along with the CSA proportion and then increases. Moreover, a higher anhydrite content mitigates the drying shrinkage and hinders the strength development. Finally, considering the properties of both the fresh and hardened binder, the ternary blends with 5% anhydrite and OPC/CSA ratios ranging from 3/7 to 2/8 were identified as most suitable for applications that require a high early strength, stable late strength, and small level of shrinkage.

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.

Microstructure and Properties of High Performance Concrete with Steel Slag Powder

2011 ◽  
Vol 675-677 ◽  
pp. 503-506
Author(s):  
Yun Feng Li
Keyword(s):  
Cement Paste ◽  
High Performance ◽  
High Performance Concrete ◽  
Cement Mortar ◽  
Steel Slag ◽  
Drying Shrinkage ◽  
Mineral Admixture ◽  
Slag Powder ◽  
Steel Slag Powder ◽  
Active Admixture

As an active admixture, super fine steel slag powder can be mixed into concrete to produce high performance concrete. The microstructures between cement paste mixed with steel slag powder and plain cement paste are experimentally studied. The SEM of the microstructures shows that microstructure of cement paste are changed by active mineral admixture, the internal structure of the cement paste are improved. Drying shrinkage of cement mortar with different steel slag kinds and different dosage of admixtures are measured. Experiments results show the effect of steel slag powder on drying shrinkage of cement mortar.

Sign in / Sign up

Export Citation Format

Share Document