The Role of Nanotechnology in Subgrade and Pavement Engineering: A Review

Nanotechnology is an extension of sciences and technologies that deal with particles less than 100 nm. This paper reviews previous studies on how nanomaterials work and what their advantages are in subgrade and pavement engineering. In subgrade engineering, the nanomaterials particles can not only improve the physicochemical and mechanical properties of subgrade soils by filling the voids between soil particles but also promote hydration reaction between cement and ion exchange between soil particles. In pavement engineering, the water stability, rutting resistance, fatigue resistance and optical properties of flexible pavements are enhanced by adding nanomaterials into the asphalt mixture. Nanosilica enhances the interface between cement pastes and aggregates and promotes the pozzolanic reaction of concrete, thus, mechanical properties of concrete pavements are improved. Compared with traditional materials, nanomaterials play a promising role in subgrade and pavement engineering, benefitting from their environmental friendliness, lower environmental disturbance, better price/performance ratio and higher durability.

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Research and Application of Slag–Nanosilica Stabilizer for Silt Subgrade

Applied Sciences ◽

10.3390/app11178014 ◽

2021 ◽

Vol 11 (17) ◽

pp. 8014

Author(s):

Xiushan Wang ◽

Shunxin Qi ◽

Bowen Dong ◽

Keyu Chen ◽

Mingjie Wang ◽

...

Keyword(s):

Mechanical Properties ◽

Rapid Development ◽

Early Period ◽

High Strength ◽

Pozzolanic Reaction ◽

Hydration Reaction ◽

Mixture Ratio ◽

Soil Particles ◽

Thaw Cycle ◽

New Type

With the rapid development of construction and road engineering, the accumulation of silting waste soil is becoming more and more serious. In order to recycle the silt, a new type of stabilizer was developed in this study to improve its mechanical properties and applicability on roads. The optimal ratio of stabilizer components was determined by orthogonal test and grey correlation analysis. The effects of stabilizer on the macroscopic mechanical properties of silt were investigated by unconfined compressive strength (UCS) test and split test. The water stability test and freeze–thaw cycle test were carried out to study the durability and road performance of stabilized soil. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) methods were used to study the effect of the stabilizer on the microstructure and mechanism of silt. The results showed that the optimal mixture ratio of the new type of stabilizer was quicklime: nanosilica: slag = 32:3:65. Adding 10% stabilizer is a reasonable and effective method to strengthen silt, which has the characteristics of high strength and strong durability in the early period. The addition of stabilizer will result in hydration reaction, pozzolanic reaction, and cation exchange on the surface of soil particles with silt, which will enhance the intermolecular force of soil particles, reduce the porosity of soil, and strengthen the connection between soil particles.

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Utilization of Solid Waste from Brick Industry and Hydrated Lime in Self-Compacting Cement Pastes

Materials ◽

10.3390/ma14051109 ◽

2021 ◽

Vol 14 (5) ◽

pp. 1109

Author(s):

Mati Ullah Shah ◽

Muhammad Usman ◽

Muhammad Usman Hanif ◽

Iqra Naseem ◽

Sara Farooq

Keyword(s):

Mechanical Properties ◽

Solid Waste ◽

Manufacturing Industry ◽

Setting Time ◽

Hydrated Lime ◽

Pozzolanic Reaction ◽

Early Age ◽

Cement Pastes ◽

Brick Powder ◽

High Degree

The huge amount of solid waste from the brick manufacturing industry can be used as a cement replacement. However, replacement exceeding 10% causes a reduction in strength due to the slowing of the pozzolanic reaction. Therefore, in this study, the pozzolanic potential of brick waste is enhanced using ultrafine brick powder with hydrated lime (HL). A total of six self-compacting paste mixes were studied. HL 2.5% by weight of binder was added in two formulations: 10% and 20% of waste burnt brick powder (WBBP), to activate the pozzolanic reaction. An increase in the water demand and setting time was observed by increasing the replacement percentage of WBBP. It was found that the mechanical properties of mixes containing 5% and 10% WBBP performed better than the control mix, while the mechanical properties of the mixes containing 20% WBBP were found to be almost equal to the control mix at 90 days. The addition of HL enhanced the early-age strength. Furthermore, WBBP formulations endorsed improvements in both durability and rheological properties, complemented by reduced early-age shrinkage. Overall, it was found that brick waste in ultrafine size has a very high degree of pozzolanic potential and can be effectively utilized as a supplementary cementitious material.

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Review on Applications of Lignin in Pavement Engineering: A Recent Survey

Frontiers in Materials ◽

10.3389/fmats.2021.803524 ◽

2022 ◽

Vol 8 ◽

Author(s):

Hui Yao ◽

Yiran Wang ◽

Junfu Liu ◽

Mei Xu ◽

Pengrui Ma ◽

...

Keyword(s):

Low Cost ◽

Asphalt Mixture ◽

Complex Mixture ◽

Development Trend ◽

Environmental Benefits ◽

Extraction Technology ◽

Environmental Friendliness ◽

Modified Asphalt ◽

Soil Stabilizer ◽

Pavement Engineering

Lignin is the second-largest plant polymer on Earth after cellulose. About 98% of lignin produced in the papermaking and pulping industry is used for combustion heating or power generation. Less than 2% of lignin is used in more valuable fields, mainly in the formulation of dispersants, adhesives, and surfactants. Asphalt is one of the most important materials in pavement engineering. It is a dark brown complex mixture composed of hydrocarbons with different molecular weights and their non-metallic derivatives. Because the chemical structure of lignin is similar to that of asphalt, it is a carbon-based hydrocarbon material. More researchers studied the application of lignin in pavement engineering. In this paper, the structure, application, and extraction technology of lignin were summarized. This is a review article describing the different applications of lignin in pavement engineering and exploring the prospects of the application. There are three main types of pavement materials that can be used for lignin in pavement engineering, which are asphalt, asphalt mixture, and roadbed soil. In asphalt, lignin can be used as a modifier, extender, emulsifier, antioxidant, and coupling agent. In asphalt mixtures, lignin can be used as an additive. In road base soils, lignin can be used as a soil stabilizer. Furthermore, the article analyzed the application effects of lignin from the life cycle assessment. The conclusions suggest that lignin-modified asphalt exhibits more viscosity and hardness, and its high-temperature resistance and rutting resistance can be significantly improved compared with conventional asphalt. In addition, some lignin-modified asphalt binders exhibit reduced low-temperature crack resistance and fatigue resistance, which can be adjusted and selected according to the climate change in different regions. The performance of lignin as an asphalt mixture additive and asphalt extender has been proved to be feasible. Lignin can also produce good mechanical properties as well as environmental benefits as a soil stabilizer. In summary, lignin plays an important role in asphalt pavement and roadbed soil, and it is likely to be a development trend in the future due to its environmental friendliness and low cost. More research is needed to generalize the application of lignin in pavement engineering.

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Experimental Study on Mechanical Properties of Fly Ash Stabilized with Cement

Advances in Civil Engineering ◽

10.1155/2020/6410246 ◽

2020 ◽

Vol 2020 ◽

pp. 1-11

Author(s):

Shengquan Zhou ◽

Yongfei Zhang ◽

Dawei Zhou ◽

Weijian Wang ◽

Dongwei Li ◽

...

Keyword(s):

Mechanical Properties ◽

Compressive Strength ◽

Fly Ash ◽

Early Stage ◽

Strain Curve ◽

Pozzolanic Reaction ◽

Hydration Reaction ◽

Hydration Products ◽

Compressive Test ◽

Plastic Properties

Cement-fly ash mixture has been commonly used for the foundation treatment projects in the fly ash stratum, as it is effective in improving foundation bearing capacity and reducing settlement of stratum. In order to figure out the effect of dynamic and static load on the mechanical properties exhibited by the cement-fly ash and the reaction mechanism of cement-fly ash, a combination of the unconfined compressive test, impact test, scanning electron microscopy (SEM), and X-ray diffraction (XRD) method was adopted in this study to investigate the cement-fly ash test samples. As demonstrated by the results, the observed growth rate of 0–60 days (d) is higher than that in the later stages and the typical stress-strain curve can be divided into six sections under the unconfined compressive test. At the gas pressure of 0.2 MPa, the cement-fly ash samples exhibited obvious plastic properties in early curing time (0–60 d), and brittle failure was observed in the final stage (90 d). It is obvious that the value of dynamic compressive strength (DCS) is higher than that of unconfined compressive strength (UCS). The analysis of XRD has revealed that the hydration products are primarily derived from the hydration reaction of cement in the early stage and the pozzolanic reaction in the late stage. The pores of cement-fly ash are found to be filled with the hydration products, despite the presence of a mass of pores in the interior.

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Hydration and Strength Development of Cementitious Materials Prepared with Phosphorous-Bearing Clinkers

Materials ◽

10.3390/ma14030508 ◽

2021 ◽

Vol 14 (3) ◽

pp. 508

Author(s):

Lilan Xie ◽

Min Deng ◽

Jinhui Tang ◽

Kaiwei Liu

Keyword(s):

Mechanical Properties ◽

Raw Materials ◽

Cementitious Materials ◽

Raw Material ◽

Strength Development ◽

Hydration Reaction ◽

Low Grade ◽

Hydration Kinetics ◽

Cement Pastes ◽

The One

To rationally use low-grade phosphorous limestone as the raw materials for cement production, the influence of phosphorous introduced by fluorapatite during the clinker calcination process on the mechanical properties of cementitious materials is investigated. Hydration kinetics, phase evolutions, and microstructure of cement pastes have been studied by using calorimetry, X-ray diffraction (XRD), and scanning electron microscopy (SEM). The results indicate that the mechanical properties of cementitious materials can be slightly improved due to the mineralization effect of the small amount of phosphorous in the clinker and significantly decreased with an increase of phosphorous. High content of phosphorous will reduce the content of C3S and make the formation of α′-C2S-xC3P(x: 0–0.05), whose hydration reactivity is rather lower, such that on the one hand less-hydrated products, such as calcium silicate hydrate (C-S-H) gel, can be obtained, and on the other hand, the hydration reaction will be slowed by severely prolonging the induction period. Interestingly, small particles can be observed on the surface of hydration products, but no new phase can be detected by XRD. When the content of P2O5 is 2.0%, the cement can meet the requirements of P·II 42.5 cement in China. Hopefully, this can provide significant guidance for the use of cement prepared by fluorapatite as raw material.

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Study on modification mechanism of workability and mechanical properties for graphene oxide-reinforced cement composite

Nanomaterials and Nanotechnology ◽

10.1177/1847980420912601 ◽

2020 ◽

Vol 10 ◽

pp. 184798042091260

Author(s):

Yuxia Suo ◽

Rongxin Guo ◽

Haiting Xia ◽

Yang Yang ◽

Feng Yan ◽

...

Keyword(s):

Mechanical Properties ◽

Compressive Strength ◽

Graphene Oxide ◽

Calcium Hydroxide ◽

Calcium Silicate ◽

Calcium Silicate Hydrate ◽

Inverse Correlation ◽

Cement Composite ◽

Hydration Reaction ◽

Cement Pastes

Graphene oxide/cement composite was prepared using a graphene oxide aqueous solution. The workability and mechanical properties of graphene oxide/cement composite with different concentrations for graphene oxide and the ratio of water to cement were investigated. The results observed were the fluidity of cement pastes decreased noticeably with the addition of graphene oxide and increased with the increase in the ratio of water to cement for all tested samples of different graphene oxide contents. It is indicated that a noticeable inverse correlation between the concentration of graphene oxide and fluidity was observed, and a positive linear relationship between the ratio of water to cement and fluidity was also obtained. The compressive strength of cement pastes significantly improved in the presence of an appropriate concentration of graphene oxide as compared to that of the cement paste without graphene oxide; this difference was due to the denser microstructure of graphene oxide/cement composite than that of the control specimens. With the combined analysis of X-ray diffraction and scanning electron microscopy with energy-dispersive spectrometry, the results showed that graphene oxide could promote and regulate the formation and connection of calcium hydroxide and calcium silicate hydrate during the hydration reaction, forming numerous regular and extremely compact plate-shaped crystals, and the compact plate-shaped microstructures constituted of not only calcium hydroxide and calcium silicate hydrate but also wrapped ettringite. This investigation will provide a flexible way to preparation of graphene oxide/cement composite with wanted fluidity and optimized compressive strength that promote the industry application of graphene oxide/cement composite.

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Laboratory investigation on effects of solid waste filler on mechanical properties of porous asphalt mixture

Construction and Building Materials ◽

10.1016/j.conbuildmat.2021.122436 ◽

2021 ◽

Vol 279 ◽

pp. 122436

Author(s):

Yu Tian ◽

Lijun Sun ◽

Hui Li ◽

Hengji Zhang ◽

John Harvey ◽

...

Keyword(s):

Mechanical Properties ◽

Solid Waste ◽

Laboratory Investigation ◽

Asphalt Mixture ◽

Porous Asphalt

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Effect of Hydrogen Nanobubbles on the Mechanical Strength and Watertightness of Cement Mixtures

Materials ◽

10.3390/ma14081823 ◽

2021 ◽

Vol 14 (8) ◽

pp. 1823

Author(s):

Won-Kyung Kim ◽

Young-Ho Kim ◽

Gigwon Hong ◽

Jong-Min Kim ◽

Jung-Geun Han ◽

...

Keyword(s):

Mercury Intrusion Porosimetry ◽

Cement Mortar ◽

Stable State ◽

Pozzolanic Reaction ◽

Hydration Reaction ◽

High Concentration ◽

Mercury Intrusion ◽

Electron Microscope Analysis ◽

Mixing Water ◽

Cement Mixtures

This study analyzed the effects of applying highly concentrated hydrogen nanobubble water (HNBW) on the workability, durability, watertightness, and microstructure of cement mixtures. The number of hydrogen nanobubbles was concentrated twofold to a more stable state using osmosis. The compressive strength of the cement mortar for each curing day was improved by about 3.7–15.79%, compared to the specimen that used general water, when two concentrations of HNBW were used as the mixing water. The results of mercury intrusion porosimetry and a scanning electron microscope analysis of the cement paste showed that the pore volume of the specimen decreased by about 4.38–10.26%, thereby improving the watertightness when high-concentration HNBW was used. The improvement in strength and watertightness is a result of the reduction of the microbubbles’ particle size, and the increase in the zeta potential and surface tension, which activated the hydration reaction of the cement and accelerated the pozzolanic reaction.

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