Effect of Additional Surfaces on Ordinary Portland Cement Early-Age Hydration

In order to stimulate the potential cementitious property of granulated blast furnace slag (GBFS), the ground GBFS sample (Wei Fang Iron and Steel Corporation, China) was activated by lime and gypsum under different dosages. The results showed that lime is an effective activator for the slag, and the optimum dosage of lime is about 10% (w/w) of the slag. At the optimum dosage of lime, the 28 days compressive strength of the lime-slag paste is higher than that of 32.5 ordinary Portland cement (OPC). But, the early age strength (3 and 7 days compressive strength) of the lime-slag paste is lower than that of the OPC. Addition of gypsum can effectively improve the early age strength of the lime-slag paste. At the ratio of gypsum:lime:slag of 8.2:9.2:82.6 (w/w), both the early and long-term compressive strengths of the gypsum-lime-slag paste are higher than that of the OPC. According to XRD, TG-DTA and SEM detections of the hydration products of the lime-slag paste, the gypsum-lime-slag paste and the OPC paste, it reveals that the hydration process of the GBFS-based cementitious material is different from the ordinary Portland cement and the presence of ettringite (AFt) contributes to the early age strength of the pastes. The major hydration product of the OPC paste (<7 days) were measured as ettringite (AFt), but the AFt phase was not detected in the hydration product of the lime-slag paste and the major hydration product of the lime-slag paste was determined as amorphous CSH gel. However, AFt was detected in the hydration products of the gypsum-lime-slag paste in the early stages of hydration, and the formation of AFt is favorable for the early strength improvement of the material.

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Difference in Strength Development between Cement-Treated Sand and Mortar with Various Cement Types and Curing Temperatures

Materials ◽

10.3390/ma13214999 ◽

2020 ◽

Vol 13 (21) ◽

pp. 4999

Author(s):

Lanh Si Ho ◽

Kenichiro Nakarai ◽

Kenta Eguchi ◽

Yuko Ogawa

Keyword(s):

Portland Cement ◽

Ordinary Portland Cement ◽

Bound Water ◽

Curing Temperature ◽

Strength Development ◽

Early Age ◽

Cement Type ◽

A Value ◽

Water To Cement Ratio ◽

Novel Method

To improve the strength of cement-treated sand effectively, the use of various cement types was investigated at different curing temperatures and compared with the results obtained from similar mortars at higher cement contents. The compressive strengths of cement-treated sand specimens that contained high early-strength Portland cement (HPC) cured at elevated and normal temperatures were found to be higher than those of specimens that contained ordinary Portland cement (OPC) and moderate heat Portland cement at both early and later ages. At 3 days, the compressive strength of the HPC-treated sand specimen, normalized with respect to that of the OPC under normal conditions, is nearly twice the corresponding value for the HPC mortar specimens with water-to-cement ratio of 50%. At 28 days, the normalized value for HPC-treated sand is approximately 1.5 times higher than that of mortar, with a value of 50%. This indicates that the use of HPC contributed more to the strength development of the cement-treated sand than to that of the mortar, and the effects of HPC at an early age were higher than those at a later age. These trends were explained by the larger quantity of chemically bound water observed in the specimens that contained HPC, as a result of their greater alite contents and porosities, in cement-treated sand. The findings of this study can be used to ensure the desired strength development of cement-treated soils by considering both the curing temperature and cement type. Furthermore, they suggested a novel method for producing a high internal temperature for promoting the strength development of cement-treated soils.

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Reverse extraction of early-age hydration kinetic equation from observed data of Portland cement

Science China Technological Sciences ◽

10.1007/s11431-010-3228-9 ◽

2010 ◽

Vol 53 (6) ◽

pp. 1540-1553 ◽

Cited By ~ 10

Author(s):

Lin Wang ◽

Bo Yang ◽

XiuYang Zhao ◽

YueHui Chen ◽

Jun Chang

Keyword(s):

Kinetic Equation ◽

Portland Cement ◽

Early Age ◽

Early Age Hydration

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Effect of Superplasticizer Type and Dosage on early-Age Shrinkage of Portland Cement and Rice Husk Ash Pastes

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.450-451.407 ◽

2012 ◽

Vol 450-451 ◽

pp. 407-412 ◽

Cited By ~ 1

Author(s):

Gritsada Sua-Iam ◽

Natt Makul

Keyword(s):

Portland Cement ◽

Rice Husk ◽

Ordinary Portland Cement ◽

Rice Husk Ash ◽

Early Age ◽

Polycarboxylate Ether

In this work, the effect of superplasticizer type and dosage on early-age shrinkage of ordinary Portland cement (OPC) and rice husk ash paste (RHA) was investigated. The OPC and RHA pastes with a water/binder materials ratio (W/B) by weight of 0.22 and various dosages of polycarboxylate ether-based superplasticizers (PCE) and sulphonated naphthalene formaldehyde condensates (SNF) were investigated. RHA was partially substituted of 0%, 10% and 20 % by weight of OPC. Volumetric shrinkages of the pastes at the first 72 hours of hydration have been found to range from 0.28 to 12.26 mm3/g and from 0.20 to 9.04 mm3/g of binder materials for SNF-based and PCE-based superplasticizers, respectively. The PCE-based superplasticizer can decrease an increase in shrinkage of the OPC and RHA pastes higher than those of containing the SNF-based superplasticizer.

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