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 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.

Improvement of Durability of Precast Concrete Member by Granulated Blast Furnace Slag Sand

2017 ◽  
Vol 12 (3) ◽  
pp. 456-469 ◽  
Author(s):  
Toshiki Ayano ◽  
◽  
Takashi Fujii ◽  
Kyoji Niitani ◽  
Katsunori Takahashi ◽  
...  
Keyword(s):  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Precast Concrete ◽  
Heavy Traffic ◽  
Concrete Slabs ◽  
Fine Aggregate ◽  
Freezing And Thawing ◽  
Steam Curing ◽  
Granulated Blast Furnace Slag ◽  
Furnace Slag

Concrete deck slabs of bridges are often deteriorated by heavy traffic and freezing and thawing actions. Spraying salt during the winter further promotes the deterioration of concrete. Some reports estimate that the length of highway roads requiring the renewal of deteriorated concrete slabs exceeds 230 km. In order to extend the lifespan of damaged bridge girders, the load for these girders must not be increased. This means that prestressed concrete (hereafter, PC) members are desirable to sustain bridge life, because they can be thinner than reinforced concrete (hereafter, RC) members. In addition, to shorten the period of traffic regulation during renewal construction, precast members should be applied. One problem in manufacturing durable precast concrete is steam curing. When the temperature, period, or both of the steam curing process are inadequate, the effect of air-entraining (hereafter, AE) agents is lost because the warmed air trapped by the AE agent expands and escapes from the concrete. Another problem is concrete fatigue. It is well known that the fatigue lives of concrete slabs in wet conditions are much shorter than those in dry conditions. Concrete slabs are waterproofed immediately after construction, but the waterproofing can be fractured soon after opening bridges, and water can reach the concrete surface. The lifespan of concrete slabs in contact with water often depends on the fatigue of the concrete. Granulated blast furnace slag sand (hereafter, BFS) can enhance the resistance to freezing and thawing actions without using AE agents. Therefore, the resistance to freezing and thawing of concrete mixed with BFS is not damaged by steam curing. The fatigue of concrete in water is also improved by the addition of BFS. Furthermore, BFS can reduce the drying shrinkage of concrete. It is advantageous to restrict the loss of prestress in PC. This study shows that precast PC members with high durability can be manufactured when granulated blast furnace slag is used as a fine aggregate in the concrete. BFS reacts with cement hydrates. It is well known that the carbonation of concrete with ground granulated blast furnace slag (hereafter, GGBF) is much greater than that with ordinary binder. However, BFS does not accelerate the carbonation of concrete. When using granulated blast furnace slag as a fine aggregate, no disadvantage in the concrete properties is detected.

Life Cycle CO2 Emission Assessment for Non-Steam Curing Precast Concrete

2014 ◽  
Vol 1025-1026 ◽  
pp. 539-542
Author(s):  
Taeh Young Kim ◽  
Sung Ho Tae ◽  
Keun Hyeok Yang
Keyword(s):  
Compressive Strength ◽  
Life Cycle ◽  
Physical Properties ◽  
Production Process ◽  
Room Temperature ◽  
Precast Concrete ◽  
Building Structures ◽  
Steam Curing ◽  
Concrete Form ◽  
Early Strength

Researches on development of technology to reduce CO2 emission while satisfying physical properties during production of precast concrete, which is mainly applied to building structures, are necessary. Accordingly, a high early strength type mixture for which removal of precast concrete form can be done by curing at room temperature instead of steam curing in the production process of precast concrete was developed. The developed high early strength type mixture was mixed with concrete to conduct coagulation, slump, and compressive strength property tests. In addition, CO2 emission and reduction performance of non-steam curing precast concrete were assessed.

Study of Productivity Improvement on Precast Concrete by Calcium Silicate Hydrate Type Accelerator

2018 ◽  
Vol 936 ◽  
pp. 214-218
Author(s):  
Hiromitsu Koyama ◽  
Toshimi Matsumoto ◽  
Jing Cui ◽  
Shigeyuki Date
Keyword(s):  
Precast Concrete ◽  
Curing Temperature ◽  
Estimation Accuracy ◽  
Efficient Production ◽  
Curing Time ◽  
Steam Curing ◽  
Productivity Improvement ◽  
Maturity Method ◽  
Test Result ◽  
Strength Improvement

The effect of early strength improvement of concrete with C-S-H type accelerator was studied for precast concrete efficient production under the steam curing condition. From the mortar test result, the effect of this improvement was confirmed to tend lager as the W/C is lower. This accelerator could short the curing time for 0.5-2.0 hours under the same temperature condition, and could reduce the curing temperature under the same curing time. Then the compressive strength was considered to be predicted by some formula, and it showed higher estimation accuracy of the Arrhenius’s Law than that of the Maturity Method.

scholarly journals Optimization of Steam-Curing Regime for Recycled Aggregate Concrete Incorporating High Early Strength Cement—A Parametric Study

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2487 ◽  
Author(s):  
Asad Hanif ◽  
Yongjae Kim ◽  
Muhammad Usman ◽  
Cheolwoo Park
Keyword(s):  
Total Duration ◽  
Recycled Aggregate Concrete ◽  
Peak Temperature ◽  
Curing Temperature ◽  
Recycled Aggregate ◽  
Strength Development ◽  
Steam Curing ◽  
Aggregate Concrete ◽  
Early Strength ◽  
Curing Cycle

This paper investigates the properties of steam cured recycled aggregate concrete (RAC), in an attempt to determine the optimum conditions of the steam-curing cycle for RAC, and incorporating high early strength cement (HESC). Varying conditions of steam curing were employed. The steam-curing cycle was set based on the peak temperature, and the duration for which the peak temperature was maintained. Three peak temperatures were used for steam curing, 50 °C, 60 °C, and 70 °C, maintained for up to two hours. The compressive strength results indicated that the steam-curing cycle employing the peak temperature of 50 °C maintained for one hour with a total duration of four hours was the optimum for strength development, both at the early and late stages of hydration. Determining the optimum steam-curing temperature and duration will help reduce the associated curing cost, thus further economizing the production cost of recycled aggregate concrete.

scholarly journals Effect of Curing Conditions on Physical Properties of Mortar Blended with Expansive Agent

2019 ◽  
Vol 278 ◽  
pp. 01002
Author(s):  
Hoshina Takuya ◽  
Hiroyuki Sudo ◽  
Sinitirou Hashimoto ◽  
Sigeyuki Date
Keyword(s):  
Physical Properties ◽  
Expansion Coefficient ◽  
Precast Concrete ◽  
Expansion Ratio ◽  
Curing Temperature ◽  
Free Expansion ◽  
Curing Conditions ◽  
Expansive Agent

Assuming precast concrete using expansion material, we will confirm the influence of curing conditions on the basic physical properties of mortar with regard to the free expansion coefficient, constraint expansion coefficient and strength, using two types of expansive materials widely used in Japan . As a result, it was confirmed that the higher the curing temperature, the higher the strength regardless of the addition of the expansion material. In addition, it was confirmed that both the free expansion coefficient and the constrained expansion ratio had an effect irrespective of the curing temperature of the lime type expansion material.

Effets des cendres volantes sur le développement des résistances mécaniques des bétons préfabriqués

1996 ◽  
Vol 23 (4) ◽  
pp. 940-949
Author(s):  
Y. Maltais ◽  
J. Marchand ◽  
R. Gagné ◽  
A. Tagnit-Hamou
Keyword(s):  
Compressive Strength ◽  
Precast Concrete ◽  
Curing Temperature ◽  
Initial Increase ◽  
Thermal Curing ◽  
Portland Cement Concrete ◽  
Concrete Compressive Strength ◽  
Fly Ashes ◽  
Steam Curing ◽  
Curing Regime

The results of an investigation of the influence of fly ashes on the development of mechanical properties of concretes subjected to 24-h thermal curing are presented in this paper. In addition to the curing temperature (23 and 60 °C), the variables studied in this investigation were the type of cement (types 10 and 30) and the source of fly ashes (four different North-American class F fly ashes). Overall, 10 different concrete mixtures were tested. Test results indicate that thermal curing tends to increase significantly the concrete compressive strength in the first 24 h. Data also demonstrate that the thermal curing regime does not have any detrimental effect on the long-term compressive strength of ordinary portland cement concrete. Compressive strength of fly ash concretes was significantly reduced by thermal curing in the 1- to 28-day period, despite an initial increase. The influence of thermal curing on the development of concrete compressive strength is discussed. Key words: compressive strength, steam curing, fly ashes, precast concrete.

scholarly journals Effect of Calcium Nitrate on the Properties of Portland–Limestone Cement-Based Concrete Cured at Low Temperature

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1611
Author(s):  
Gintautas Skripkiūnas ◽  
Asta Kičaitė ◽  
Harald Justnes ◽  
Ina Pundienė
Keyword(s):  
Compressive Strength ◽  
Cement Paste ◽  
Setting Time ◽  
Calcium Nitrate ◽  
Curing Temperature ◽  
Hardened Concrete ◽  
Cement Pastes ◽  
Initial Setting Time ◽  
Initial Setting ◽  
Early Strength

The effect of calcium nitrate (CN) dosages from 0 to 3% (of cement mass) on the properties of fresh cement paste rheology and hardening processes and on the strength of hardened concrete with two types of limestone-blended composite cements (CEM II A-LL 42.5 R and 42.5 N) at different initial (two-day) curing temperatures (−10 °C to +20 °C) is presented. The rheology results showed that a CN dosage up to 1.5% works as a plasticizing admixture, while higher amounts demonstrate the effect of increasing viscosity. At higher CN content, the viscosity growth in normal early strength (N type) cement pastes is much slower than in high early strength (R type) cement pastes. For both cement-type pastes, shortening the initial and final setting times is more effective when using 3% at +5 °C and 0 °C. At these temperatures, the use of 3% CN reduces the initial setting time for high early strength paste by 7.4 and 5.4 times and for normal early strength cement paste by 3.5 and 3.4 times when compared to a CN-free cement paste. The most efficient use of CN is achieved at −5 °C for compressive strength enlargement; a 1% CN dosage ensures the compressive strength of samples at a −5 °C initial curing temperature, with high early strength cement exceeding 3.5 MPa but being less than the required 3.5 MPa in samples with normal early strength cement.

scholarly journals Phase Transformation of Kaolin-Ground Granulated Blast Furnace Slag from Geopolymerization to Sintering Process

2021 ◽  
Vol 7 (3) ◽  
pp. 32
Author(s):  
Noorina Hidayu Jamil ◽  
Mohd. Mustafa Al Bakri Abdullah ◽  
Faizul Che Pa ◽  
Mohamad Hasmaliza ◽  
Wan Mohd Arif W. Ibrahim ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Room Temperature ◽  
Curing Temperature ◽  
Curing Process ◽  
Sintering Process ◽  
Granulated Blast Furnace Slag ◽  
Fluxing Agent ◽  
Furnace Slag

The main objective of this research was to investigate the influence of curing temperature on the phase transformation, mechanical properties, and microstructure of the as-cured and sintered kaolin-ground granulated blast furnace slag (GGBS) geopolymer. The curing temperature was varied, giving four different conditions; namely: Room temperature, 40, 60, and 80 °C. The kaolin-GGBS geopolymer was prepared, with a mixture of NaOH (8 M) and sodium silicate. The samples were cured for 14 days and sintered afterwards using the same sintering profile for all of the samples. The sintered kaolin-GGBS geopolymer that underwent the curing process at the temperature of 60 °C featured the highest strength value: 8.90 MPa, and a densified microstructure, compared with the other samples. The contribution of the Na2O in the geopolymerization process was as a self-fluxing agent for the production of the geopolymer ceramic at low temperatures.

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