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

Materials ◽  
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.

scholarly journals Strength development of cement-treated sand using different cement types cured at different temperatures

2018 ◽  
Vol 195 ◽  
pp. 01006
Author(s):  
Lanh Si Ho ◽  
Kenichiro Nakarai ◽  
Kenta Eguchi ◽  
Takashi Sasaki ◽  
Minoru Morioka
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
Ordinary Portland Cement ◽  
Cement Content ◽  
Bound Water ◽  
Pozzolanic Reaction ◽  
Strength Development ◽  
Different Temperatures ◽  
Early Strength

This study aimed to investigate the strength development of cement-treated sand using different cement types: ordinary Portland cement (OPC), high early strength Portland cement (HPC), and moderate heat Portland cement (MPC) cured at different temperatures. The cementtreated sand specimens were prepared with 8% of cement content and cured under sealed conditions at 20οC and 40οC, and mortar specimens were also prepared for reference. The results showed that the compressive strength of cement-treated sand increased in order of MPC, OPC, and HPC under high curing temperatures. It was interesting that the compressive strength of the specimens using HPC was much larger than that of the specimen using OPC and MPC under 20οC due to the larger amount of chemically bound water. Additionally, it was revealed that under high curing temperatures, the pozzolanic reaction was accelerated in the cement-treated sand; this may be caused by the high proportions of sand in the mixtures.

scholarly journals Strength Development and Elemental Distribution of Dolomite/Fly Ash Geopolymer Composite under Elevated Temperature

Materials ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 1015 ◽  
Author(s):  
Emy Aizat Azimi ◽  
Mohd Mustafa Al Bakri Abdullah ◽  
Petrica Vizureanu ◽  
Mohd Arif Anuar Mohd Salleh ◽  
Andrei Victor Sandu ◽  
...  
Keyword(s):  
Elevated Temperature ◽  
Fly Ash ◽  
Portland Cement ◽  
Ordinary Portland Cement ◽  
Raw Materials ◽  
Liquid Sodium ◽  
Strength Development ◽  
Elemental Distribution ◽  
Distribution Analysis ◽  
Geopolymer Composites

A geopolymer has been reckoned as a rising technology with huge potential for application across the globe. Dolomite refers to a material that can be used raw in producing geopolymers. Nevertheless, dolomite has slow strength development due to its low reactivity as a geopolymer. In this study, dolomite/fly ash (DFA) geopolymer composites were produced with dolomite, fly ash, sodium hydroxide, and liquid sodium silicate. A compression test was carried out on DFA geopolymers to determine the strength of the composite, while a synchrotron Micro-Xray Fluorescence (Micro-XRF) test was performed to assess the elemental distribution in the geopolymer composite. The temperature applied in this study generated promising properties of DFA geopolymers, especially in strength, which displayed increments up to 74.48 MPa as the optimum value. Heat seemed to enhance the strength development of DFA geopolymer composites. The elemental distribution analysis revealed exceptional outcomes for the composites, particularly exposure up to 400 °C, which signified the homogeneity of the DFA composites. Temperatures exceeding 400 °C accelerated the strength development, thus increasing the strength of the DFA composites. This appears to be unique because the strength of ordinary Portland Cement (OPC) and other geopolymers composed of other raw materials is typically either maintained or decreases due to increased heat.

scholarly journals Hydration and Microwave Curing Temperature Interactions of Repair Mortars

2021 ◽  
Vol 03 (04) ◽  
pp. 1-1
Author(s):  
Pal S. Mangat ◽  
◽  
Shahriar Abubakri ◽  
Konstantinos Grigoriadis ◽  
Vincenzo Starinieri ◽  
...  
Keyword(s):  
Portland Cement ◽  
Heat Of Hydration ◽  
Curing Temperature ◽  
Early Age ◽  
Normal Density ◽  
Concrete Repair ◽  
Microwave Curing ◽  
Polymer Addition ◽  
Curing Period ◽  
Repair Materials

Microwave curing of repair patches provides an energy efficient technique for rapid concrete repair. It has serious economic potential due to time and energy saving especially for repairs in cold weather which can cause work stoppages. However, the high temperatures resulting from the combination of microwave exposure and accelerated hydration of cementitious repair materials need to be investigated to prevent potential durability problems in concrete patch repairs. This paper investigates the time and magnitude of the peak hydration temperature during microwave curing (MC) of six cement based concrete repair materials and a CEM II mortar. Repair material specimens were microwave cured to a surface temperature of 40-45 °C while their internal and surface temperatures were monitored. Their internal temperature was further monitored up to 24 hours in order to determine the effect of microwave curing on the heat of hydration. The results show that a short period of early age microwave curing increases the hydration temperature and brings forward the peak heat of hydration time relative to the control specimens which are continuously exposed to ambient conditions (20 °C, 60% RH). The peak heat of hydration of normal density, rapid hardening Portland cement based repair materials with either pfa or polymer addition almost merges with the end of microwave curing period. Similarly, lightweight polymer modified repair materials also develop heat of hydration rapidly which almost merges with the end of microwave curing period. The peak heat of hydration of normal density ordinary Portland cement based repair materials, with and without polymer addition, occurs during the post microwave curing period. The sum of the microwave curing and heat of hydration temperatures can easily exceed the limit of about 70 °C in some materials at very early age, which can cause durability problems.

scholarly journals Chloride Ingress in Chemically Activated Calcined Clay-Based Cement

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Joseph Mwiti Marangu ◽  
Joseph Karanja Thiong’o ◽  
Jackson Muthengia Wachira
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
Ordinary Portland Cement ◽  
Strength Development ◽  
Chloride Ingress ◽  
Calcined Clay ◽  
Apparent Diffusion Coefficients ◽  
Apparent Diffusion ◽  
Lower Porosity ◽  
Lower Chloride

Chloride-laden environments pose serious durability concerns in cement based materials. This paper presents the findings of chloride ingress in chemically activated calcined Clay-Ordinary Portland Cement blended mortars. Results are also presented for compressive strength development and porosity tests. Sampled clays were incinerated at a temperature of 800°C for 4 hours. The resultant calcined clay was blended with Ordinary Portland Cement (OPC) at replacement level of 35% by mass of OPC to make test cement labeled PCC35. Mortar prisms measuring 40 mm × 40 mm × 160 mm were cast using PCC35 with 0.5 M Na2SO4 solution as a chemical activator instead of water. Compressive strength was determined at 28th day of curing. As a control, OPC, Portland Pozzolana Cement (PPC), and PCC35 were similarly investigated without use of activator. After the 28th day of curing, mortar specimens were subjected to accelerated chloride ingress, porosity, compressive strength tests, and chloride profiling. Subsequently, apparent diffusion coefficients (Dapp) were estimated from solutions to Fick’s second law of diffusion. Compressive strength increased after exposure to the chloride rich media in all cement categories. Chemically activated PCC35 exhibited higher compressive strength compared to nonactivated PCC35. However, chemically activated PCC35 had the least gain in compressive strength, lower porosity, and lower chloride ingress in terms of Dapp, compared to OPC, PPC, and nonactivated PCC35.

Strength Development of Cemented Tailings Materials Containing Polycarboxylate ether-based Superplasticizer: Experimental Results on the Effect of Time and Temperature

2020 ◽  
Author(s):  
Sada Haruna ◽  
Mamadou Fall
Keyword(s):  
Cost Effective ◽  
Curing Temperature ◽  
Strength Development ◽  
Strength Increase ◽  
Type I ◽  
Cement Type ◽  
New Findings ◽  
Polycarboxylate Ether ◽  
Effective Design ◽  
Furnace Slag

This paper presents new findings of research conducted to experimentally assess the effects of a polycarboxylate-based superplasticizer on the strength of CPB subjected to varying curing time and temperature (2°C, 20°C, and 35°C). The binders used were Portland cement type I, fly ash and blast furnace slag. The results obtained show that the unconfined compressive strength (UCS) of the CPB containing polycarboxylate-based superplasticizer increases with time. Moreover, the increase in superplasticizer content was observed to improve the UCS of the CPB. Temperature was also observed to play an important role in strength development as the UCS increases with the rise in the curing temperature for all samples. It is also found that the temperature-induced strength increase is more significant for the CPBs that contain the superplasticizer than for those without superplasticizer. The findings from this study will be useful towards cost-effective design of backfill structures.

scholarly journals Effect of nano-SnO2 on early-age hydration of Portland cement paste

2019 ◽  
Vol 11 (6) ◽  
pp. 168781401985194 ◽  
Author(s):  
Jianping Zhu ◽  
Genshen Li ◽  
Ruijie Xia ◽  
Huanhuan Hou ◽  
Haibin Yin ◽  
...  
Keyword(s):  
Portland Cement ◽  
Cement Paste ◽  
Cement Hydration ◽  
Cementitious Materials ◽  
Hydration Process ◽  
Strength Development ◽  
Early Age ◽  
Test Machine ◽  
Portland Cement Paste ◽  
Scanning Electron

Nanomaterial, as a new emerging material in the field of civil engineering, has been widely utilized to enhance the mechanical properties of cementitious material. Nano-SnO2 has presented high hardness characteristics, but there is little study of the application of nano-SnO2 in the cementitious materials. This study mainly investigated the hydration characteristics and strength development of Portland cement paste incorporating nano-SnO2 powders with 0%, 0.08%, and 0.20% dosage. It was found that the early-age compressive strength of cement paste could be greatly improved when nano-SnO2 was incorporated with 0.08% dosage. The hydration process and microstructure were then measured by hydraulic test machine, calorimeter, nanoindentation, X-ray diffraction, scanning electron microscope, and mercury intrusion porosimetry. It was found that the cement hydration process was promoted by the addition of nano-SnO2, and the total amount of heat released from cement hydration is also increased. In addition, the addition of nano-SnO2 can promote the generations of high density C-S-H and reduce the generations of low density C-S-H indicating the nucleation effect of nano-SnO2 in the crystal growth process. The porosity and probable pore diameter of cement paste with 0.08% nano-SnO2 were decreased, and the scanning electron microscopic results also show that the cement paste with 0.08% nano-SnO2 promotes the densification of cement microstructure, which are consistent with the strength performance.

Alkali Activation of Granulated Blast Furnace Slag

2010 ◽  
Vol 158 ◽  
pp. 1-11 ◽  
Author(s):  
Zi Qiao Jin ◽  
Xian Jun Lu ◽  
Shu Gang Hu
Keyword(s):  
Compressive Strength ◽  
Blast Furnace ◽  
Portland Cement ◽  
Blast Furnace Slag ◽  
Ordinary Portland Cement ◽  
Hydration Product ◽  
Early Age ◽  
Hydration Products ◽  
Granulated Blast Furnace Slag ◽  
Furnace Slag

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.

scholarly journals Effects of Mixing and Curing Temperature on the Strength Development and Pore Structure of Fly Ash Blended Mass Concrete

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Ki-Bong Park ◽  
Takafumi Noguchi
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Pore Structure ◽  
Weather Conditions ◽  
Strength Loss ◽  
Curing Temperature ◽  
Strength Development ◽  
Mass Concrete ◽  
Term Strength

The aim of this work is to know clearly the effects of temperature in response to curing condition, hydration heat, and outside weather conditions on the strength development of high-performance concrete. The concrete walls were designed using three different sizes and three different types of concrete. The experiments were conducted under typical summer and winter weather conditions. Temperature histories at different locations in the walls were recorded and the strength developments of concrete at those locations were measured. The main factors investigated that influence the strength developments of the obtained samples were the bound water contents, the hydration products, and the pore structure. Testing results indicated that the elevated summer temperatures did not affect the early-age strength gain of concrete made using ordinary Portland cement. Strength development was significantly increased at early ages in concrete made using belite-rich Portland cement or with the addition of fly ash. The elevated temperatures resulted in a long-term strength loss in both belite-rich and fly ash containing concrete. The long-term strength loss was caused by a reduction in the degree of hydration and an increase in the total porosity and amount of smaller pores in the material.

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

2012 ◽  
Vol 450-451 ◽  
pp. 407-412 ◽  
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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