scholarly journals Strength and Road Performance of Superabsorbent Polymer Combined with Cement for Reinforcement of Excavated Soil

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Di Dai ◽  
Jie Peng ◽  
Xiaowan Zhao ◽  
Gang Li ◽  
Lanlan Bai
Keyword(s):  
Laboratory Experiments ◽  
Microscopic Analysis ◽  
Road Construction ◽  
Drying Shrinkage ◽  
Engineering Properties ◽  
Superabsorbent Polymer ◽  
X Ray Diffraction ◽  
Pavement Materials ◽  
Excavation Work ◽  
The Impact

The process of road construction is often accompanied by a large number of excavation work, and most of the excavated soil has poor engineering performance and needs to be transported away. It has the significance of environmental protection and cost saving to treat the excavated soil as pavement materials. The aim of this study is to present laboratory experiments into the mechanical properties, engineering properties, and microstructure of excavated soil stabilized by ordinary Portland cement (OPC) and superabsorbent polymer (SAP). Laboratory experiments were performed to determine unconfined compressive strength (UCS), compactness, durability after wetting and drying cycles, drying shrinkage, and California bearing ratio (CBR). Apart from these, X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used for the microstructure analysis to understand the impact of SAP on cemented excavated soil. It shows that SAP can effectively improve the strength and the compaction of cemented excavated soil with good durability. Although SAP will reduce the CBR value of cemented excavated soil, it still meets the requirements of engineering acceptance. Microscopic analysis shows that SAP absorbs water in the cemented excavated soil and plays a filling role.

scholarly journals Effect of Burn Joss Paper Ash on Properties of Ground-Granulated Blast Furnace-Based Slag Geopolymer

2020 ◽  
Vol 10 (14) ◽  
pp. 4877
Author(s):  
Wen-Ten Kuo ◽  
Chuen-Ul Juang ◽  
Zhi-Rong Chen
Keyword(s):  
Blast Furnace ◽  
Setting Time ◽  
Microscopic Analysis ◽  
Waste Recycling ◽  
Engineering Properties ◽  
X Ray Diffraction ◽  
Granulated Blast Furnace Slag ◽  
Substitution Ratio ◽  
Dry Shrinkage ◽  
Peak Value

The purpose of this study is to make geopolymers using burned joss paper ash (BJPA)—which is used in traditional Chinese festivals—and ground-granulated blast-furnace slag (GGBFS). GGBFS-based geopolymers were replaced by BJPA, by mass, at levels of 0%, 20%, 40%, 60%, 80% and 100% and the liquid-to-solid ratios (L/Ss) were 0.3, 0.4 and 0.5. The properties of fresh, hardening, durability and microscopic analysis were examined to determine the effect of BJPA-substitution ratios and L/S on the engineering properties of composite geopolymers. The results show that among the fresh properties, as the amount of BJPA replacement increases, the setting time tended to increase, but the fluidity slowed down. The maximum compressive strength reached 81.1 MPa. As the amount of BJPA replacement increased, the elastic modulus of the geopolymer increased and the brittleness decreased. However, in the dry shrinkage test, it was found that an increase in BJPA helped reduce the dry shrinkage of the geopolymer. X-ray diffraction analysis revealed that a rise in the BJPA-substitution ratio increased the peak value of calcium carbonate. Scanning electron microscope images showed that microcrack size decreased with an increase in the BJPA-substitution ratio, with maximum and minimum crack sizes of 5.80 μm and 176.8 nm, respectively. This was because BJPA was unable to undergo complete polymerization and therefore was able to fill the cracks produced during the polymerization. In conclusion, BJPA may be used for waste recycling in the production of geopolymers.

Strength and Swelling Properties of Solidified Dredged Materials

2011 ◽  
Vol 261-263 ◽  
pp. 812-815
Author(s):  
Dong Xing Wang ◽  
Rachid Zentar ◽  
Nor Edine Abriak
Keyword(s):  
Road Construction ◽  
Treatment Method ◽  
Point Of View ◽  
Engineering Properties ◽  
Swelling Properties ◽  
The Road ◽  
New Material ◽  
Traditional Approaches ◽  
The Impact

In the context of sustainable development, traditional approaches such as ocean dumping and inland deposit are unsatisfactory for managing such large quantity of dredged marine sediments. The solidified sediments with cement as a new material for road construction are preferred to resolve the present issue for minimizing the impact to environment. Based on the basal characterization of dredged sediments, a series of tests, such as compaction tests, compressive strength and tensile strength tests and swell tests, are performed to explore the engineering properties of treated materials. The compressive and tensile strengths increase with cement content and curing time, while the swell percents of sediments decrease after immersion in water for 4 days. And this treatment method could be considered adaptive and acceptable for the road construction from the point of view of swelling property. Finally, the I-CBR index of cement-treated sediments increases due to the flocculation and cementation compared to the I-CBR index before immersion.

scholarly journals Effects of Various Curing Conditions on Volume Stability of Magnesium Phosphate Cement

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Jie Wu ◽  
Zhenyu Lai ◽  
Qiubai Deng ◽  
Mengliang Liu
Keyword(s):  
Microscopic Analysis ◽  
Drying Shrinkage ◽  
Magnesium Phosphate ◽  
Repair Material ◽  
X Ray Diffraction ◽  
Road Engineering ◽  
Moisture Evaporation ◽  
Curing Conditions ◽  
Volume Stability ◽  
Water Curing

Magnesium phosphate cement (MPC) is an excellent repair material for civil and road engineering, but its volume stability under various environmental conditions significantly influences these applications. In this study, the volume stability of MPC under different curing conditions (e.g., air, standard, and water curing) is investigated. Moreover, the phases, weight loss, microstructure, and pore structure of the samples have been determined by X-ray diffraction, thermogravimetry, scanning electron microscopy, and Brunnauer–Emmet–Teller method. The results show that MPC will shrink by 8 × 10−4 under air-curing conditions. At the same time, MPC will expand by 9 × 10−4 under water-curing and standard curing conditions, which means that curing conditions influence the volume stability of MPC. Not only that, compared with air-curing conditions, the compressive strength of MPC under standard curing and water-curing conditions will decrease by 30% and 60%, respectively, which implies that greater humidity will reduce the mechanical properties of the repair material. Therefore, air curing is the best curing condition for MPC. To get a better repair effect, the environment should be avoided as much as possible in a humid state. The microscopic analysis results show that the volume expansion of MPC is related to hydration products, and the volume shrinkage occurs owing to drying shrinkage caused by internal moisture evaporation.

scholarly journals Chemical Stabilization of Black Cotton Clay and Laterite Soil Using Drycon Powder for Suitability as Construction Materials

2020 ◽  
pp. 29-39
Author(s):  
Larry Pax Chegbeleh ◽  
Frank Siaw Ackah
Keyword(s):  
Construction Material ◽  
Construction Materials ◽  
Road Construction ◽  
Atterberg Limits ◽  
Engineering Properties ◽  
X Ray Diffraction ◽  
Laterite Soil ◽  
X Ray ◽  
Significant Strength ◽  
Problem Soils

This paper used drycon powder (DP) as stabilization additive for improving the engineering properties of problem soils, specifically, black cotton clay (BCC) and laterite soil (LS), for use as a road construction material. The study was carried out in some parts of the Greater Accra Region of Ghana, through the conduction of index properties tests such as gradation, Atterberg limits, California bearing ratio (CBR), Compaction characteristics and X-ray diffraction (XRD) on the problem soils. CBR, Atterberg limits and environmental quality tests were specifically conducted on DP stabilized soils for comparative analysis. Gradation results revealed 38% fines for BCC and 14% fines for LS. X-ray diffraction analysis revealed the presence of quartz and montmorillonite in BCC, and quartz and kaolinite in LS. Generally, the results of the various tests conducted revealed that DP has the potential of improving the engineering properties of problem soils with significant strength improvement. It can also be inferred from the results that, DP is environmental friendly soil stabilizer.

Feasibility of Reusing Marine Dredged Clay Stabilized by a Combination of By-Products in Coastal Road Construction

2019 ◽  
Vol 2673 (12) ◽  
pp. 519-528 ◽  
Author(s):  
Thien Quoc Tran ◽  
Young-sang Kim ◽  
Gyeong-o Kang ◽  
Ba Huu Dinh ◽  
Tan Manh Do
Keyword(s):  
Clayey Soil ◽  
Ph Value ◽  
Road Construction ◽  
Liquid Limit ◽  
Engineering Properties ◽  
X Ray Diffraction ◽  
Initial Water ◽  
Effective Stabilizer ◽  
By Products ◽  
Water Contents

Road construction work on poor subgrade in coastal, port, and reclamation sites is a traditional challenge for geotechnical engineers because of the typically very weak clayey soil in these domains. This research investigates the effects of adding a new green binder (Fa-RmLG), in different proportions and initial water contents, on the engineering properties of marine dredged clay (MDC) collected from Yeosu port, South Korea. The new green binder used is a combination of fly ash (Fa), phosphogypsum (G), lime (L), and red mud (Rm). In this study, five binder mixtures using different proportions of Fa, G, L, and Rm were blended into MDC with different water contents varying in a range of 1.2 to 2.0 times the liquid limit (LL) value. Tests of unconfined compressive strength, California bearing ratio, swelling, and shrinkage were performed on the stabilized MDC mixtures. As a result, large increases in the strength and bearing capacity as well as significant reductions of the swelling and shrinkage values of the stabilized MDC mixtures were recorded compared with unstabilized MDC. Scanning electric microscope and X-ray diffraction analyses were performed to observe the formation and presence of gels inside the stabilized MDC mixtures. Regarding environmental impact, the pH of the stabilized MDC mixtures did not increase above the corrosive limit (pH = 12.5) by the measured pH value. These results indicate that the new green binder can be used as an effective stabilizer for the stabilization of MDC in coastal road construction.

From Silent Spring to The Frog of War

2017 ◽  
Author(s):  
David K. Skelly
Keyword(s):  
Natural History ◽  
Laboratory Experiments ◽  
Wild Populations ◽  
Rachel Carson ◽  
Chemical Agents ◽  
Silent Spring ◽  
The World ◽  
History Information ◽  
Wildlife Populations ◽  
The Impact

This chapter presents two examples to demonstrate that natural history is the necessary basis of any reliable understanding of the world. More than a half century ago, Rachel Carson revolutionized the public’s view of pesticides. The foundation of her success was the careful use of natural history data, collated from across North America. The examples she assembled left little doubt that DDT and other pesticides were causing a widespread decline in birds. More recently, the case for the impact of atrazine on wildlife was based on laboratory experiments, without the advantage of natural history observations. For atrazine, natural history observations now suggest that other chemical agents are more likely to be responsible for feminization of wildlife populations. Developing expectations for scientists to collect natural history information can help to avoid over-extrapolating lab results to wild populations, a tendency often seen when those lab results conform to preconceptions about chemicals in the environment.

scholarly journals Research on the Properties of Mineral–Cement Emulsion Mixtures Using Recycled Road Pavement Materials

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 563
Author(s):  
Łukasz Skotnicki ◽  
Jarosław Kuźniewski ◽  
Antoni Szydło
Keyword(s):  
Road Construction ◽  
Base Layer ◽  
Asphalt Emulsion ◽  
Reclaimed Asphalt ◽  
Pavement Materials ◽  
Road Pavement ◽  
Road Surfaces ◽  
Cement Binder ◽  
Pavement Structures ◽  
By Products

The reduction in natural resources and aspects of environmental protection necessitate alternative uses of waste materials in the area of construction. Recycling is also observed in road construction where mineral–cement emulsion (MCE) mixtures are applied. The MCE mix is a conglomerate that can be used to make the base layer in road pavement structures. MCE mixes contain reclaimed asphalt from old, degraded road surfaces, aggregate improving the gradation, asphalt emulsion, and cement as a binder. The use of these ingredients, especially cement, can cause shrinkage and cracks in road layers. The article presents selected issues related to the problem of cracking in MCE mixtures. The authors of the study focused on reducing the cracking phenomenon in MCE mixes by using an innovative cement binder with recycled materials. The innovative cement binder based on dusty by-products from cement plants also contributes to the optimization of the recycling process in road surfaces. The research was carried out in the field of stiffness, fatigue life, crack resistance, and shrinkage analysis of mineral–cement emulsion mixes. It was found that it was possible to reduce the stiffness and the cracking in MCE mixes. The use of innovative binders will positively affect the durability of road pavements.

scholarly journals Review of the relationship between aggregates geology and Los Angeles and micro-Deval tests

2021 ◽  
Vol 80 (3) ◽  
pp. 1963-1980
Author(s):  
Solomon Adomako ◽  
Christian John Engelsen ◽  
Rein Terje Thorstensen ◽  
Diego Maria Barbieri
Keyword(s):  
Los Angeles ◽  
Crystal Size ◽  
Grain Shape ◽  
Mechanical Performance ◽  
Pore Space ◽  
Construction Material ◽  
Engineering Properties ◽  
Coarse Grained ◽  
The Impact ◽  
The Relationship

AbstractRock aggregates constitute the enormous volume of inert construction material used around the globe. The petrologic description as igneous, sedimentary, and metamorphic types establishes the intrinsic formation pattern of the parent rock. The engineering properties of these rocks vary due to the differences in the transformation process (e.g. hydrothermal deposits) and weathering effect. The two most common mechanical tests used to investigate the performance of aggregates are the Los Angeles (LA) and micro-Deval (MD) tests. This study reviewed the geological parameters (including mineralogy, grain and crystal size, grain shape, and porosity) and the relationship to Los Angeles and micro-Deval tests. It was found that high content of primary minerals in rocks (e.g. quartz and feldspar) is a significant parameter for performance evaluation. Traces of secondary and accessory minerals also affect the performance of rocks, although in many cases it is based on the percentage. Furthermore, some studies showed that the effect of mineralogic composition on mechanical strength is not sufficient to draw final conclusions of mechanical performance; therefore, the impact of other textural characteristics should be considered. The disposition of grain size and crystal size (e.g. as result of lithification) showed that rocks composed of fine-grain textural composition of ≤ 1 mm enhanced fragmentation and wear resistance than medium and coarse grained (≥ 1 mm). The effect of grain shape was based on convex and concave shapes and flat and elongated apexes of tested samples. The equidimensional form descriptor of rocks somehow improved resistance to impact from LA than highly flat and elongated particles. Lastly, the distribution of pore space investigated by means of the saturation method mostly showed moderate (R = 0.50) to strong (R = 0.90) and positive correlations to LA and MD tests.

scholarly journals The impact of point defects in n-type GaN layers on thermal decomposition of InGaN/GaN QWs

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mikolaj Grabowski ◽  
Ewa Grzanka ◽  
Szymon Grzanka ◽  
Artur Lachowski ◽  
Julita Smalc-Koziorowska ◽  
...  
Keyword(s):  
Quantum Wells ◽  
High Temperatures ◽  
Point Defects ◽  
X Ray Diffraction ◽  
Helium Ions ◽  
X Ray ◽  
Sapphire Substrates ◽  
Transmission Electron ◽  
The Impact ◽  
Ingan Quantum Wells

AbstractThe aim of this paper is to give an experimental evidence that point defects (most probably gallium vacancies) induce decomposition of InGaN quantum wells (QWs) at high temperatures. In the experiment performed, we implanted GaN:Si/sapphire substrates with helium ions in order to introduce a high density of point defects. Then, we grew InGaN QWs on such substrates at temperature of 730 °C, what caused elimination of most (but not all) of the implantation-induced point defects expanding the crystal lattice. The InGaN QWs were almost identical to those grown on unimplanted GaN substrates. In the next step of the experiment, we annealed samples grown on unimplanted and implanted GaN at temperatures of 900 °C, 920 °C and 940 °C for half an hour. The samples were examined using Photoluminescence, X-ray Diffraction and Transmission Electron Microscopy. We found out that the decomposition of InGaN QWs started at lower temperatures for the samples grown on the implanted GaN substrates what provides a strong experimental support that point defects play important role in InGaN decomposition at high temperatures.

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