Engineering Construction Materials Research Articles

Feasibility of Microbially Induced Carbonate Precipitation to Enhance the Internal Stability of Loess under Zn-Contaminated Seepage Conditions

Loess is widely distributed in Northwestern China and serves as the preferred engineering construction material for anti-fouling barriers. Heavy metal contamination in soil presents significant challenges to the engineering safety of vulnerable loess structures. Hence, there is an urgent need to investigate the impact of heavy metal ions on their percolation performance. In order to investigate the effectiveness of microbially induced carbonate precipitation (MICP) using Sporosarcina pasturii (CGMCC1.3687) bacteria in reducing internal seepage erosion, a saturated permeability test was conducted on reshaped loess under constant water head saturation conditions. The response of loess to deionized water (DW) and ZnCl2 solution seepages was analyzed by monitoring changes in cation concentration over time, measuring Zeta potential, and using scanning electron microscopy (SEM). The results indicate that the hydrolysis of Zn2+ creates an acidic environment, leading to the dissolution of carbonate minerals in the loess, which enhances its permeability. The adsorption of Zn2+ ions and the resulting diffusion double-layer (DDL) effect reduce the thickness of the diffusion layer and increase the number of free water channels. Additionally, the permeability of loess exposed to ZnCl2 solution seepage significantly increased by 554.5% compared to loess exposed to deionized water (DW) seepage. Following the seepage of ZnCl2 solutions, changes in micropore area ratio were observed, decreasing by 48.80%, while mesopore areas increased by 23.9%. MICP treatment helps reduce erosion and volume shrinkage in contaminated loess. Carbonate precipitation enhances the erosion resistance of contaminated loess by absorbing or coating fine particles and creating bridging connections with coarse particles. These research results offer new perspectives on enhancing the seepage properties of saturated loess in the presence of heavy metal erosion and the geochemical mechanisms involved.

Effect of curing conditions on the alkali-activated blends: Microstructure, performance and economic assessment

To enhance the application of alkali-activated materials in engineering, this study investigates the influence of cast-in-place and prefabrication by steam curing and autoclaved curing on alkali-activated materials with different slag-fly ash mass ratios. The selection of the three curing methods is based on current construction techniques: onsite construction (ambient curing), production of prefabricated cement-based components (steam curing), and production of aerated concrete blocks (autoclaved curing). In this paper, the dissolution ability of CaO, SiO2 and Al2O3 in fly ash and slag was first evaluated. Subsequently, the hydration products of the samples were analyzed using X-ray diffraction, thermogravimetric analysis, and a scanning electron microscope. Additionally, the degree of hydration of the samples was quantitatively analyzed using the selective dissolution method combined with 29Si NMR. The results showed that compared to ambient curing, autoclaved curing, which provides a high-temperature and high-pressure environment, enhances the reactivity of slag and fly ash. This enhancement is reflected in the increase in their solubility and the degree of reaction from 28.3% to 14.6%–69.9% and 63.7% respectively. The pore structure, compressive strength, and shrinkage of the samples were also evaluated. The results demonstrate that autoclaved curing enhances the formation of hydration products, reduces porosity, and increases compressive strength. Compared to ambient curing, steam curing can reduce the shrinkage rate from 64.8% to 68.4%, while autoclaved curing can decrease it from 87.9% to 95.1%. Based on the economic analysis, autoclaved curing can offset the total costs by reducing the usage of slag and lowering raw material expenses, demonstrating its cost-effectiveness. The obtained results can provide a theoretical foundation for the large-scale application of alkali-activated slag-fly ash materials in civil engineering construction.

Aeolian sand stabilized by using fiber- and silt-reinforced cement: Mechanical properties, microstructure evolution, and reinforcement mechanism

Northwest China has a large amount of aeolian sand, which exhibits poor gradation, low cohesive force, and loose structure; thus, this sand is difficult to be directly used as engineering construction materials. To solve this problem, this study mixed fiber, silt, and cement to stabilize aeolian sand. The effects of the fiber content (0%, 0.5%, 1%, 2%, 3%, and 4%), fiber length (6, 12, and 19 mm), silt content (10%, 15%, and 20%), and curing time (7, 14, and 28 d) were evaluated by conducting indoor unconfined compressive strength tests, and the strength prediction and constitutive models were established. In addition, the microstructural and pore variation characteristics were studied by performing scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and nuclear magnetic resonance (NMR) tests, and the stability mechanism was elucidated. The results showed that the addition of fibers and silt can significantly improve the strength and ductility of cement-stabilized aeolian sand. Under the optimal mixing conditions (fiber length: 12 mm; fiber content: 2%; silt content: 15%), the strength of the sample increased by 274.2% (reaching 1684 kPa) compared with that of cement-stabilized aeolian sand (450 kPa). A positive correlation was observed between the curing time and strength development of the samples. The established strength prediction model effectively predicted the strength variations in the specimens, whereas the constitutive model accurately reflected the stress-strain relationship of the specimens. The SEM results revealed that the coupling effect of fibers, silt, and cement makes the specimens more compact and improves the overall stability. The results of the NMR showed that the numbers of macropores and mesopores decreased significantly and that the numbers of small pores and micropores increased with 2% fiber content; the porosity of the specimen was 12.3%, which was 28.6% lower than that of ordinary-cement-stabilized aeolian sand. This study advocates making full use of local silt to stabilize aeolian sand, which has significant advantages in terms of improved mechanical properties, environmental protection, and reduced project costs compared with traditional cement-stabilized aeolian sand. The results of this study have important theoretical and practical significance for the engineering and design of projects in aeolian sand areas.

Research on Random Induced Vibration Response of Stone Pavement by Engineering Construction Material Vehicles

Research on Random Induced Vibration Response of Stone Pavement by Engineering Construction Material Vehicles

Conversion of recycled sludge waste into high value-added ceramics as engineering construction materials: Fabrication, characterization and performance evaluation

Sludge from municipal wastewater treatment plants usually exhibits extremely homologous traits with clay in both mineralogical component and chemical composition, and accordingly it can be utilized as an alternative feedstock for clay to fabricate engineering construction materials and advance sludge valorization. In this work, different proportions of wastewater treatment plant sludge (WTPS) were incorporated into kaolin to develop value-added construction ceramic materials. The thermal behavior, crystalline composition, physicochemical performance, microscopic characteristics and sintering mechanism of value-added ceramics were investigated. The results showed that WTPS not only contained a large amount of inorganic components such as SiO2, Al2O3 and Fe2O3, but also rich organic compounds, which contributed to the formation of pore structure inside the ceramics during sintering. Different WTPS addition did not affect the types of crystalline components in sintered ceramics, but markedly impacted the sintering behavior. Only when the WTPS dosage reached 40 wt%, the original mixtures would be fully sintered into construction ceramics with the apparent porosity of 11.30 %, thermal conductivity of 0.50 W/(m·K), bulk density of 2.22 g/cm3, linear shrinkage and volume shrinkage of 14.95 % and 38.86 % respectively, as well as vastly low water absorption (0.58 %) and excellent flexural strength (84 MPa). However, with the WTPS content up to 50 wt%, the flexural strength of sintered ceramics was reduced to 50 MPa, despite the elevated sintering degree, which was related to the high formation of liquid phase and the violent expansion of several closed pores. Therefore, converting WTPS into high value-added construction ceramic products is an operable and beneficial way to achieve sludge waste recycling, reduction and stability.

Use of Time–Temperature Superposition and Stepped Isothermal Method for Estimating Long-Term Properties of Recycled Aggregate Roller-Compacted Concrete

Abstract Although the use of recycled materials in civil engineering construction is a desirable option from a sustainability standpoint, the questionable long-term performance of these materials often hinders their widespread use in practice. The primary focus of this study was to perform accelerated aging and testing for estimating long-term properties of a roller-compacted concrete composed of crushed recycled aggregate, Type-I portland cement, and ASTM Class-F fly ash replacing up to 50 % of cement by weight. Accelerated aging was accomplished by curing cylindrical specimens at three different elevated temperature regimes for specific time durations. At the end of each time–temperature regime, the residual stiffness of the specimen was measured in a nondestructive fashion. Series of stiffness–time master curves were then constructed for each mix using the time–temperature superposition (TTS) technique and the stepped isothermal method (SIM). While the TTS method uses different sets of specimens for each elevated time–temperature regime, SIM uses a single set of specimens that are stepped up in temperature and held at each regime for a specified duration. Results indicated that for all mixes, the material stiffness degraded with time. Based on the Arrhenius equation, stiffness–equivalent age master curves were developed. Stiffness prediction was accomplished up to an equivalent age of almost 600 days, although the actual short-term test lasted only up to 6 days. It was also found that SIM and TTS provided comparable results, thus implying that the testing time and the number of specimens can be significantly reduced by using the SIM.

Properties and Microcosmic Mechanism of Coral Powder Modified Asphalt in Offshore Islands and Reefs Construction

The application of waste coral fragments from natural weathering, harbor construction and channel excavation to infrastructure construction on offshore islands can help alleviate the problems of shortage of traditional materials, land use of waste materials, and long-distances transport. In order to promote the comprehensive application of coral materials in road engineering construction on offshore islands, and to develop road pavement materials with good service performances and economic and environmental benefits, this paper studies the base properties, high-temperature rheological properties, and microstructure of coral powder (CP) modified asphalt through indoor experiments. The base properties tests (penetration, softening point and ductility) showed that the incorporation of CP increased the stiffness and high-temperature stability of the asphalt, but decreased the ductility of the asphalt. The optimal dosing of CP in virgin asphalt (VA) and styrene-butadiene-styrene-modified asphalt (SA) is 12% and 15%, respectively. The results of viscosity and high-temperature rheology tests showed that the right amount of CP could improve the high-temperature rheological properties and resistance to permanent deformation of asphalt, but superfluous CP tends to have a negative effect. Microscopic test results show that in the recommended dosage, the combination effect of CP and asphalt is better. CP-modified asphalt is mainly based on physical modification.

Application Analysis of Green Building Materials in Civil Engineering Construction

Application Analysis of Green Building Materials in Civil Engineering Construction

Discussion on Material Testing of Municipal Traffic Engineering

At present, the rapid development of municipal traffic engineering is in line with the high quality development trend and the demand for accurate management. The municipal traffic builders strictly control the quality from the aspects of planning and design, construction management, material testing, measurement and acceptance, among which material testing is an important part. The quality of engineering construction materials directly determines the final quality of engineering construction, so the layout and planning of material control must be done well in the actual implementation process. A preliminary investigation was conducted from the aspects of material classification and detection, material parameter selection, material grading and control, etc., so as to realize the centralized management of the three responsible parties of design, construction and suppliers, further standardize the program and standardization of municipal traffic construction projects, and achieve the goal of excellent construction project quality.

New insights into the seepage behavior of heavy metal-contaminated loess and its underlying geochemical mechanism

Heavy metal contamination in soils can pose severe challenges to the safety of geotechnical engineering projects. Loess, which is widely distributed in Northwest China, is a preferred engineering construction material for anti-fouling barriers. Therefore, research on the influence of heavy metal ions on its seepage performance is urgently required. To obtain new insights into the seepage behavior of heavy metal-contaminated loess and its underlying geochemical mechanism, laboratory investigations were performed on the saturated hydraulic conductivity (Ksat), leaching, and microstructural characteristics of loess contaminated with Cu2+ and Zn2+. The results indicate that the hydrolysis of Zn2+ creates an acidic environment, which promotes the dissolution of carbonate minerals in loess, enhances the leaching capacity, and leads to the quantitative transformation of small pores (2–8 μm) to mesopores (8–32 μm). Meanwhile, the alternating adsorption of Zn2+ and its diffuse double-layer effect compresses the diffusion layer, increasing the abundance of free water channels. Thus, the Ksat of Zn-contaminated loess increases by 81.2% during the seepage period. As for Cu-contaminated loess, its seepage behavior is the opposite of that of Zn-contaminated loess, with a Ksat decrease of nearly 50%. The primary factor controlling this phenomenon is the formation and enrichment of Cu2O in the lower part of the soil, which inhibits the enlargement of pores and reduces the effective connectivity of pores. The findings of this work provide insight into the seepage behavior of saturated loess under erosion by heavy metals and the underlying geochemical mechanism thereof.

Fragment theoretical model of concrete blocks subjected to blast loads

Concrete, a typical engineering construction material, will fracture and fragment when subjected to blast loads. In this study, the blast experiments on concrete blocks were carried out using 30kg of explosive B at different stand-off distances, and the concrete fragments were recovered, sieved, weighed, and counted to obtain information of the fragments in different particle size groups. Moreover, the propagation process of the blast energy was analyzed based on the blast theory, and the deformation energy of the concrete blocks subjected to the blast loads was calculated according to the deformation energy theory. The Griffith fracture theory was employed to estimate the energy dissipation during the fragmentation of the concrete blocks, and the initial kinetic energy of the concrete fragments was determined by combining it with the kinematics theory. Subsequently, a fragment theoretical model was developed based on the principle of energy conservation. The validity of the proposed fragment theoretical model was verified by comparing the statistical data of the blast experiments. The present fragment theoretical model can predict the fragmentation degree of concrete members reasonably and effectively and calculate the particle sizes and quantity of concrete fragments under unknown blast load conditions.

Application of green building materials in civil engineering construction

Application of green building materials in civil engineering construction

Characterizations of Lime Sludge from Indian Paper Industry: A Step towards Sustainable Growth for Indian Cement Industry

The kraft process of wood into wood pulp in the paper and pulp industry in the chemical recovery section generates lime sludge (LS) through the burning of the lime kiln. This by-product lime sludge from the paper industry has the major chemical composition of calcium carbonate in the form of calcite, moisture and minors are silica, magnesium, iron and aluminium. Here, we characterized the collected industrial lime sludge by-product from different parts of the country and evaluated its potential application in engineering construction material. The chemical composition of all samples contains CaO in around (52-55) %, SiO2 (1-4) %, Al2O3 and Fe2O3 make up less than 1% by weight. Minor alkalis of Na2O, K2O and SO3 content are less than 1 wt%. XRD profile and TG/DTA results showed that all lime sludge samples have major calcite (CaCO3) phase. The particle size distribution showed that grains are in the range of 11μm to 23μm which is compatible for cement manufacture and construction. Investigation by optical microscopy of microstructure and morphology revealed that calcite grains are presents as rounded shape agglomerated form. The characterization of all obtained results are encouraging for replacement of limestone in the cement and construction industry by using lime sludge which is technically suitable and economically viable for waste management in favour of circular economy.

Innovation and application of green building materials in civil engineering construction

As people' s requirements for building quality are getting higher and higher, the use of building materials in civil engineering construction should also meet the modern environmental protection requirements. Therefore, it is proposed that the innovation and application of green building materials in civil engineering construction and analysis of green The characteristics of building materials, the innovative application of green building materials in engineering construction based on the characteristics, the use of green materials in building structures, the innovative application of exterior decoration, and the innovative application of interior decoration. Realize the application of green building materials in civil engineering construction.

Opportunities and challenges for engineering construction materials as carbon sinks

Population growth and urbanization over the coming decades are anticipated to drive unprecedented demand for infrastructure materials and energy resources. Unfortunately, factors such as the degree of resource consumption, the energy-intensive nature of production, and the chemical-reaction driven emissions make infrastructure materials production industries among the greatest contributors to anthropogenic CO2 emissions. Yet there is an often-overlooked potential environmental benefit to infrastructure materials: most remain in use for decades and their long service lives can facilitate extended storage of carbon. In this perspective, we present an overview of recent technological advancements that can support infrastructure materials acting as a global, distributed carbon sink and discuss areas for further research and development. We present mechanisms to quantify the extent to which the embodied carbon will be removed from the carbon cycle for a long enough period of time to provide carbon sequestration and climate benefit. We conclude that it is possible to unlock the vast potential to engineer a carbon sequestration system that simultaneously meets societal need for expanding infrastructure systems; however, complexities in how these systems are engineered must be systematically and quantitatively incorporated into materials design.

Analysis on the Application of Green Building Materials in Civil Engineering Construction

Analysis on the Application of Green Building Materials in Civil Engineering Construction

Research on Current Situation and Development Direction of Civil Engineering Construction Based on Intelligent New Materials

Intelligent new building materials are further improved in the perception level of internal and external environment, as well as the feedback ability of materials themselves. Therefore, it can make further response to the environment while improving the building performance, so it can be widely used in civil engineering construction. Based on this, this paper first studies the classification and function of intelligent new civil building materials, then analyses the structure and composition of intelligent new materials in civil engineering construction, and finally gives the application and development of intelligent new materials in wood engineering construction.

Research on Green Building Materials in Civil Engineering Management System

The development of the real estate industry has increased the application market capacity of green building materials, and the demand for green building materials has also greatly increased. The formation of the concept of pollution-free, energy-saving and environmentally friendly housing by consumers has gradually changed the choice of traditional civil engineering construction materials and Cost control. The application and promotion of a large number of green building materials in civil engineering construction has laid a material foundation for the construction of energy-saving and environmentally friendly buildings in China. The article is based on this, using inorganic raw materials potassium silicate, sodium silicate, and silica sol as base materials, add a certain proportion of organic silicon modified styrene-acrylic emulsion, and then add titanium dioxide, kaolin, talc, nano-titanium dioxide and other fillers and coating film-forming additives to prepare water-based inorganic coatings. The test results show that the prepared coating has good physical and chemical properties, environmental protection performance, and fire resistance performance, and can be widely used in the construction industry with obvious social and economic benefits and environmental protection benefits.

Application of Green Building Materials in Civil Engineering Construction

The continuous economic and social progress of our country has helped the rapid progress of civil engineering projects. However, the relatively improved civil engineering project creation also has many shortcomings, such as waste of resources, depletion, and pollution of the natural environment. The construction project itself is an item. The energy consumption is relatively high. Due to the shortage of resources and the more serious natural environment and ecological problems, the public pays more attention to the related problems of their own quality of life, and more and more people are adopting green building materials. Therefore, it is very important to explore the application of green building materials in civil engineering projects.

Cement-treated recycled glass and crushed rock blends: modulus of rupture and stiffness properties

ABSTRACT Recycled waste materials are increasingly being used as low carbon construction materials in civil infrastructure works, as recycled materials have significant carbon savings compared with virgin quarried materials. In this research, the stiffness and modulus of rupture properties of crushed rock (CR) blended with recycled glass (RG) were evaluated. The engineering properties of the four cement-treated CR/RG blends evaluated were: 100% CR100 (100CR), 90% CR with 10% RG (CR90/RG10), 80% CR with 20% RG (CR80/RG20), 70% CR with 30% RG (CR70/RG30). 3% dosage of general blend (GB) cement was used in all the RG/ CR blends. The results indicated that cement-treated RG/CR blends, with up to 20% RG, are suitable as pavement subbase materials. Unconfined compression strength (UCS) values met the minimum requirement for 7 days of curing for all the CR/RG blends. The results of repeated load triaxial (RLT) tests and flexural beam tests were found to be within the ranges reported for the previous testing on other accepted recycled and quarry products. Based on this laboratory assessment, RG can be recommended for incorporation as a supplementary material in cement-treated CR pavement applications, which will increase the uptake of recycled products as a civil engineering construction material.