Early-age performance of longitudinal bridge joints made with shrinkage-compensating cement concrete

2019 ◽  
Vol 197 ◽  
pp. 109391 ◽  
Author(s):  
Weizhuo Shi ◽  
Behrouz Shafei ◽  
Zhengyu Liu ◽  
Brent M. Phares
Keyword(s):  
Early Age ◽  
Cement Concrete ◽  
Bridge Joints

Research of Zero Stress Temperature Gradient in Cement Concrete Pavement

2013 ◽  
Vol 723 ◽  
pp. 163-170 ◽  
Author(s):  
Xiang Shen Hou ◽  
Xin Kai Li ◽  
Bo Peng ◽  
Guang Hui Deng
Keyword(s):  
Temperature Gradient ◽  
Concrete Beam ◽  
Concrete Slab ◽  
Strain Sensor ◽  
Concrete Pavement ◽  
Early Age ◽  
Cement Concrete ◽  
Setting Process ◽  
Cement Concrete Pavement ◽  
Design Guidance

There is no temperature stress and temperature curling according to the present cement concrete pavement design, when the temperature gradient of cement concrete pavement in service is zero, and it does not consider the effect of Built-in curling caused in early-age setting process of cement concrete to cement concrete pavement in service. In fact, there is Built-in curling in cement concrete slab when it is after the completion of the cement concrete slab is poured, and the curling is mainly upward. It is in the setting process, when cement concrete is on the final set, the cement concrete is at the critical moment when is just able to bear load, and it exists temperature gradient but no strain in the pavement slab, the temperature gradient is known as "Built-in construction temperature gradient" in AASHTO2002 design guidance, and it is the important part of the Built-in curling. In this paper, cement concrete beam specimens were poured in outdoor and temperature sensor and strain sensor were buried in the cement concrete specimens to detect early-age internal temperature field and strain field, and then the study of Built-in curling and Built-in construction temperature gradient were carried out.

Influences of Initial Curing Conditions on the Microstructure of Fly Ash Cement System

2010 ◽  
Vol 168-170 ◽  
pp. 532-536 ◽  
Author(s):  
Guo Li ◽  
En Li Lu ◽  
Peng Wang ◽  
Ou Geng ◽  
Yong Sheng Ji
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Cement Mortar ◽  
Early Age ◽  
Concrete Durability ◽  
Cement Concrete ◽  
Hydration Degree ◽  
Curing Conditions ◽  
Cement System ◽  
C 30

In order to study the influences of initial curing conditions on fly ash (FA) cement concrete durability, fly ash cement samples with 30% replacement ratio were fabricated and cured in water at 10°C, 20°C, 30°Cand 40°C for 3d, 7d, 14d and 28d respectively. Hydration degrees of fly ash at early age were measured using the selective dissolve method. Correspondingly the pore structure and morphology of FA-cement mortar and compared cement mortar were studied by using MIP and SEM methods. Then early age compressive strengths of FA-cement concrete and compared normal cement concrete were tested. Experimental results show that initial curing temperatures and ages are important factors to fly ash early age hydration degree, FA-cement system microstructure, morphology and early age compressive strength etc. High curing temperatures and longer curing time can lead higher fly ash hydration degree, and then higher compressive strength of FA-cement concrete, and make the micro-structures of fly ash-cement system denser.

scholarly journals Experimental study on fiber mortar strength at early age under temperature difference

2019 ◽  
Vol 264 ◽  
pp. 02005
Author(s):  
Yan Zhang ◽  
Ning Li
Keyword(s):  
High Temperature ◽  
Temperature Difference ◽  
Concrete Structure ◽  
Early Age ◽  
Experimental Basis ◽  
Cement Concrete ◽  
Influence Of Temperature ◽  
Mortar Strength ◽  
Strength Change ◽  
Strength Difference

The condition of high temperature is easy to destroy the concrete structure of tunnels. Many temperature difference conditions are applied to ordinary mortar and fiber mortar specimens, the early strength values of mortar caused by temperature change were measured. The flexural strength change rules of the specimens were analysed. The influence of temperature difference on different specimens, and the cause of the strength difference and failure of the specimens are studied. It provides experimental basis for improving the service life of high temperature tunnel cement concrete structure.

Influence of High-Temperature Curing on the Properties of the Concrete Containing Ground Iron and Steel Slag

2014 ◽  
Vol 507 ◽  
pp. 337-342
Author(s):  
Meng Yuan Li ◽  
Jin Hu
Keyword(s):  
Compressive Strength ◽  
High Temperature ◽  
Steel Slag ◽  
Curing Temperature ◽  
Early Age ◽  
Cement Concrete ◽  
Chloride Permeability ◽  
Iron And Steel ◽  
Negative Effect ◽  
Curing Condition

The influence of high-temperature curing on the compressive strength and chloride permeability of the concrete containing ground iron and steel slag (GISS) was investigated. Under standard curing condition (20°C), the early-age compressive strength of the concrete with GISS is much lower than that of the pure cement concrete. The activity of GISS is more sensitive to the increase of curing temperature than that of cement. The increase amplitude of early-age strength of the concrete with GISS is much greater than that of the pure cement concrete by increasing curing temperature. Increasing curing temperature tends to decease the late-age strength and enhance the late-age permeability of concrete. The negative effect of increasing curing temperature on the late-age properties of the concrete with GISS is smaller than that of the pure cement concrete.

Mechanical Properties of Alite-Calcium Barium Sulphoaluminate Cement Concrete

2008 ◽  
Vol 400-402 ◽  
pp. 121-124
Author(s):  
Zong Hui Zhou ◽  
Ling Chao Lu ◽  
Xing Kai Gao ◽  
Xin Cheng
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Portland Cement ◽  
Cement Paste ◽  
Early Age ◽  
Hardened Cement ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Hardened Cement Paste ◽  
Sulphoaluminate Cement

In this paper, preparation and mechanical properties of Alite-calcium barium sulphoaluminate (Alite-C2.75B1.25A3 ) cement concrete were studied. The results showed the compressive strength of Alite-C2.75B1.25A3 cement concrete was much higher than that of Portland cement concrete, especially the early-age compressive strength. The 24-hour compressive strength of Alite-C2.75B1.25A3 cement concrete could reach 22.81Mpa for w/c=0.45, 17.29Mpa for w/c=0.50 and 17.04Mpa for w/c=0.55 respectively. They were about 50 to 65 percent higher than those of Portland cement concrete. The 7-day compressive strength could reach about 80 to 90 percent of 28-day strength for Alite-C2.75B1.25A3 cement concrete. The 28-day strength could reach 55.85Mpa for w/c=0.45, 48.01Mpa for w/c=0.50 and 44.21Mpa for w/c=0.55 respectively. The results of SEM showed the interfaces between the hardened cement paste and aggregates in Alite-C2.75B1.25A3 cement concrete were more compact than those in Portland cement concrete. Distribution of particulate bulk was more uniformity and a majority of clinker particles was wrapped by hydrated gel in Alite-C2.75B1.25A3 concrete. And, the structure of Alite-C2.75B1.25A3 cement concrete was much more compact than that of Portland cement concrete.

Research of Built-In Temperature and Zero Stress Temperature of Cement Concrete Pavement at Early Ages

2013 ◽  
Vol 857 ◽  
pp. 248-255 ◽  
Author(s):  
Chang Bin Hu ◽  
Mu Lu Du ◽  
Li Juan Wang
Keyword(s):  
Field Tests ◽  
Concrete Pavement ◽  
Early Age ◽  
Base Temperature ◽  
Cement Concrete ◽  
Cement Concrete Pavement ◽  
Different Seasons ◽  
Numerical Simulation Methods ◽  
Gradient Type ◽  
Negative Gradient

Based on field tests and numerical simulation methods, distribution characteristics of early-age built-in temperature of cement concrete pavement constructed in different seasons and pouring time were analyzed firstly. Then considering effect of creep, characteristics of early-age zero stress temperature in cement concrete that built-in temperature of cement concrete pavement constructed in different seasons and pouring time has a great difference. The distributions of built-in temperature along the thickness present nonlinear obviously, and they have four typical types: concave and positive gradient type, concave negative gradient type, convex positive gradient type and convex negative gradient type. Zero stress temperature gradient shows prominently developing process compared with built-in temperature of slab at different ages by the effect of creep. Zero stress temperature of slab poured on am7:00 in summer firstly increase and then decline. Besides, the positive gradient change to negative gradient gradually, and the gradient of zero stress temperature trend to decrease. At last, it is recommended to calculate zero stress temperature of slab consideration of base temperature and the nonlinear distributions characteristics, and the combined effect of creep and age.

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