Multifunctional, Sustainable, and Biological Non-Ureolytic Self-Healing Systems for Cement-Based Materials

Microbially induced calcium carbonate(CaCO_(3))precipitation(MICP)has been investigated as a sustain-able alternative to conventional concrete remediation methods for improving the mechanical properties and durability of concrete structures.To date,urea-dependent MICP is the most widely employed MICP pathway in biological self-healing concrete research as its use has resulted in efficient CaCO_(3) precipita-tion rates.NH_(3) is a byproduct of ureolysis,and can be hazardous to cementitious structures and the health of various species.Accordingly,non-ureolytic bacterial concrete self-healing systems have been developed as eco-friendly alternatives to urea-dependent self-healing systems.Non-ureolytic pathways can improve the physical properties of concrete samples and incorporate the use of waste materials;they have the potential to be cost-effective and sustainable.Moreover,they can be applied in terrestrial and marine environments.To date,research on non-ureolytic concrete self-healing systems has been scarce compared to that on ureolytic systems.This article discusses the advances and challenges in non-ureolytic bacterial concrete self-healing studies and highlights the directions for future research.

Sustainable Construction—Use of Stone Dust as Plasticiser in High Strength SCC with Blended Cement

Extensive growth in the developing countries due to infrastructure development is resulting into massive consumption of concrete thereby increasing the demand on concrete materials. Quite large amounts of fine aggregates are required for concrete in developing countries thus shortages of quality river sand is putting pressure on availability of fine aggregates. To fulfill the high demand of fine aggregates, a search for alternative materials is in process. Stone crushing and processing industry is a large industry which generates large amounts of stone dust and slurry which is a waste produced from this process. Tons of such waste generated has no useful purpose except as landfill material. Some preliminary studies have been conducted into use of marble/ limestone waste for use in concrete [1] [2].?This study aims at using stone dust as partial replacement of sand in concrete to observe its effects on workability and other mechanical properties. This would result in useful consumption of this waste product thereby eliminating environmental issues related to its disposal. Partial replacement of 10% and 20% sand replacement with stone dust is carried out with the use of self-compacting concrete with blended cement. Blended cement used contains 50% rice husk ash and 50% Portland cement. Such high strength SCC with blended cement containing 50% rice husk ash and 50% Portland cement has already been tested to provide better quality concrete [3]. Wide ranging investigations covering most aspects of mechanical behavior and permeability were carried out for various mixes for compressive strengths of 60?MPa & 80?MPa. Compressive strengths of high strength SCC with blended cements and 10% and 20% replacement of sand with stone dust for 60?MPa and 80?MPa were observed to be higher by about 10% to 13% than the control specimen. Higher elastic moduli and reduced permeability were observed along with better sulphate and acid resistance. Better strengths and improved durability of such high strength SCC make it a more acceptable material for major construction projects thereby reducing the burden on environment and use of such waste product for a useful purpose promoting sustainable construction.

Sustainable Construction—High Performance Concrete Containing Limestone Dust as Filler

Massive amounts of limestone waste are produced by the stone processing industry worldwide. Generally, it is believed that 60% to 70% of the stone is wasted in processing in the form of fragments, powder and slurry out of which around 30% is in the form of fine powder [1]. This waste has no beneficial usage and poses environmental hazards. Use of this waste product in the construction industry can largely reduce the amount of waste to be disposed off by the local municipalities in addition to reducing large burden on the environment. Some basic research on use of limestone dust as cement/ concrete filler?has?been carried out in the recent past but high strength/ high performance concretes have not been investigated yet [2] [3]. The concrete industry is among the largest consumer of raw materials worldwide and has been investigated for use of various types of waste materials like crushed brick, rice husk and straw ash as either aggregates for concrete or as partial cement substitutes. Use of limestone dust as filler material in concrete can consume a huge amount of this waste material which has to be disposed off otherwise, creating large burden on the environment. This experimental study aimed at evaluating the properties of high performance concretes made from Portland cement, natural aggregates and sand. Limestone dust was added by replacing sand in the percentages of 10% and 20%. Wide ranging investigations covering most aspects of mechanical behavior and permeability were carried out for various mixes for compressive strengths of 60?N/mm2, 80?N/mm2 and 100?N/mm2. Compressive strengths of concrete specimen with partial replacement of sand with 10% and 20% limestone dust as filler material for 60?N/mm2, 80N/mm2 and 100?N/mm2 were observed to be higher by about 4% to 12% than the control specimen. Flexural strengths were also observed to be higher by 12%?-?13%. Higher elastic moduli and reduced permeability were observed along with better sulphate and acid resistance. Better strengths and improved durability of such high-performance concretes make it a more acceptable material for major construction projects.

Sustainable Use of Steel Industry Slag (SIS) for Concrete Production: A State Art of Review

This paper presents a review on the sustainable use of steel industry slag (SIS) in the construction industry for sustainable development. This issue also may contribute significantly to attain the sustainable development goal (SDG). If feasible sector is not determined earlier for the use of SIS for the country like Bangladesh then the unproductive uses will be increased and as well without large-scale utilization, direct dumping of SIS will create environmental hazards. On the other hand, the sustainable use of SIS in concrete production can contribute to the economic growth of the country;in addition, it can also contribute to keeping our natural environment safe from hazardous pollution. Another observation of this study is SIS used in cement and concrete production as aggregate or as additional cementing materials has a long-term strength and durability. Besides, replacement of cement with SIS deferred the hydration reaction at early ages, without any significant troubles. Furthermore, it can also be mentioned that high replacement of SIS with cement may raise a problem of volume instability which can be solved by using ground-granulated blast-furnace slag (GGBS) as combined admixture and the slump problem of concrete mixtures can be adjusted with addition of copper slag or class F fly ash. Feasibility analysis of SIS usage and an awareness program for all the stakeholders may be implemented for the sustainable uses of SIS. Both of these will play a vital role to safeguard environment in addition to economic growth of the country.

The Properties and Applications of High-effective Mineral Admixture GRM for Concrete

To utilize industrial residue as building materials is not only the demand for modern concrete technology but also the requirements for maintaining ecological balance and sustainable development. CRM, a new high-effective mineral admixture for concrete, is developed recently from industrial residue, and the systematical studies on CRM’s various properties have been performed. The laboratory tests, industrial tests and field applications have shown that CRM can be used as inorganic cementitious material to replace cement, and is also an excellent supplementary cementitious material tor high performance concrete (HPC).

Effective Contribution of Brazilian Rice Husk Silica(RHS)as Eco-Friendly Silica in Concrete Plants

Due to growing consumption of Portland cement and high levels of CO_(2) emissions in its production process,this study examined the use of Brazilian RHS(rice husk silica)obtained by FBC(fluidized bed combustion)as an alternative material in concrete production;the principal cause is the inappropriate disposal of carbonized or in natura rice husk in southern Brazil.To analyze its feasibility,concretes made with several types of cements were examined combined with RHS,and also concretes with different strength classes employing a slag-based binder featuring a smaller amount of clinker in its composition.Mechanical and scanning electron microscopy assays were carried out to verify formation of C-S-H and calcium hydroxide in the cement pastes.This study concludes that replacing 10%of Portland cement(CEMIII/A)by 3%of RHS can result in a cost reduction of around 5%and allows a reduction of 4%in CO_(2)eq levels.In this way,RHS from renewable sources can be a highly impactful sustainable alternative in civil engineering work,allowing the concrete industry to produce environmentally-sound concrete mixtures with lower CO_(2) emissions.

High-Performance and Multifunctional Cement-Based Composite Material

Concrete is a continuously evolving material, and even the definition of high-performance concrete has changed over time. In this paper, high-performance characteristics of concrete material are considered to be those that support the desirable durability, resilience, and sustainability of civil infrastructure that directly impact our quality of life. It is proposed that high-performance material characteristics include tensile ductility, autogenous crack-width control, and material “greenness.” Furthermore, smart functionalities should be aimed at enhancing infrastructure durability, resilience, and sustainability by responding to changes in the surrounding environment of the structure in order to perform desirable functions, thus causing the material to behave in a manner more akin to certain biological materials. Based on recent advances in engineered cementitious composites (ECCs), this paper suggests that concrete embodying such high-performance characteristics and smart multifunctionalities can be designed, and holds the potential to fulfill the expected civil infrastructure needs of the 21st century. Highlights of relevant properties of ECCs are provided, and directions for necessary future research are indicated.

Recent developments in the application of oil palm fibers in cement composites

Fibers obtained from different parts of the oil palm tree(Elaeis guineensis)have been under investigation for possible use in construction.Studies have been carried out investigating the engineering properties and possible applications of these fibers.However,the experimental methods employed and the values of mechanical and physical properties recorded by various authors are inconsistent.It has therefore become necessary to organize information which would be useful in the design of oil palm fiber cement composites and help researchers and engineers make informed decisions in further research and application.This review provides information about fibers from different parts of the oil palm,their properties,enhancement techniques,current and potential application in cement composites.

Study of bond strength between various grade of Ordinary Portland Cement(OPC)and Portland Pozzolane Cement(PPC)mixes and different diameter of TMT bars by using pullout test

Since last two decades,the Portland Pozzolane Cement(PPC)is extensively used in structural concrete.But,till to date,a few literature is available on bond strength of concrete using PPC mixes.There are many literatures available on bond strength of concrete mixes using Ordinary Portland Cement(OPC).Hence,a comparative study was conducted on bond strength between OPC and PPC mixes.In the present investigation,total 24 samples consisting of M20,M35 and M50 grades of concrete and 16 and 25 mm diameter of TMT bar were tested for 7 and 28 days.The pullout bond test was conducted on each specimen as per IS:2770-1967/1997[1]and the results were observed at 0.25 mm slip at loaded end called as critical bond stress and at maximum bond load called as maximum bond stress.It was observed that the critical bond strength of PPC mixes is 10%higher than OPC mixes.Whereas,marginal improvement was noticed in maximum bond strength of PPC mixes.Hence,based on these findings,it could be concluded that development length for PPC mixes could be reduced by 10%as compared with same grade of OPC mixes.

工业废弃木质素固化土特性及其在岩土工程中的应用进展

为明确工业废弃木质素在岩土工程中的应用现状和存在问题,探寻用于突破现有木质素改良土体技术的科学方法和工程措施,笔者在已有研究基础上,介绍了木质素在岩土工程中的应用状况,探讨了木质素与土体间的相互作用机制,指出了需要解决的关键问题和下一步研究的方向。结果表明:木质素对砂性土和黏性土均具有提高力学性能、抵抗水分侵入的效果,土体的韧性特征得到明显提高;木质素产生的胶结作用是土体微观结构和宏观工程性质改善的根本原因,阐明胶结物质的生成机制是揭示其改良土体机制的关键;木质素固化土在恶劣环境中的耐久性能需进一步提升,相应的施工工艺和工程防护措施仍不完备;对木质素进行化学改性,增强其胶结与耐久性能,系统研究土颗粒胶结与改良土的应力应变特征以及扩宽木质素的土体处置对象均是值得继续深入研究的科学问题。

低碳混凝土在交通建设中的应用分析

本文通过对新型混凝土材料在工程中的创新应用进行分析,旨在探讨低碳混凝土材料在交通建设领域的研发、生产和应用,以实现绿色交通的可持续发展目标。通过应用分析,总结出新型混凝土材料在生产过程和工程应用中的碳排放效果显著,且提高了工程质量,为交通建设的可持续性发展提供了有力支撑。

绿色高性能混凝土与建筑工程材料的可持续发展

建筑工程材料的难题始终是建筑行业内部关心的重点,而绿色环保也逐渐成为现代化社会发展的特征和要求。虽然中国各地方气候条件差别较大,但是人们对住房环境的需求却比较一致。一般来说,建筑单位都会采用大批的高能耗建筑材料来保证居民生活的舒适度,但是这也大大降低了建筑工程的经济效益和环保性。为了促进建筑行业节能环保,本文为绿色高性能混凝土与建筑工程材料的可持续发展做出了详细分析,以供相关人员参考。

典型混凝土视角下的绿色-可持续发展混凝土的发展及研究现状

为了解绿色-可持续发展混凝土研究现状,方便后续研究者设计科学的研究方案,采用文献分析等方法系统梳理相关研究成果,并以再生混凝土、高性能混凝土和生态混凝土3种典型混凝土为载体,对绿色-可持续发展混凝土的发展历程及研究现状进行介绍和评述。同时以中国知网全文数据库相关文献为依托,从发文量和主题词角度分析了绿色-可持续发展混凝土当前研究的热点。在此基础上预测未来绿色-可持续发展混凝土研究的方向,即研发智能混凝土、自动修复功能混凝土以及类混凝土新材料。

探索建筑垃圾绿色再生混凝土的强度特性机理

随着城市化建设的快速发展,混凝土消耗量呈现持续增长的趋势,而建筑固体废物产生量也急剧上升。鉴于土地资源的有限性、环境污染的加剧、社会效益和经济效益的综合考量,国家倡导可持续发展和绿色环保的理念,将再生混凝土作为我国城市建筑发展的一个重要方向。通过对再生混凝土进行单轴压缩试验,研究了再生混凝土在受压时的应力变化规律。反弯段的极限峰值应变在相同加载速率条件下趋向稳定,这表明加载速率与极限峰值应力之间并没有显著关系。结果得出:在龄期和加载速率相同的情况下,配比不同的再生混凝土试块在上升段杨氏模量变化趋势一致,但与配合比参数关系不明显。

混凝土浇筑施工技术在绿色住宅建筑工程中的应用

文章旨在探讨混凝土浇筑施工技术在绿色住宅建筑工程中的应用。对绿色住宅建筑的标准与要求、混凝土浇筑施工流程以及绿色住宅建筑混凝土结构的环保要求进行了分析,重点介绍了低能耗混凝土配比设计与优化、高效节能浇筑设备与工艺、智能监控系统以及废弃物回收利用等创新技术在绿色住宅中的应用。研究表明,这些技术的应用有效促进了绿色住宅的可持续发展,实现了社会效益、生态效益和经济效益的统一。

新型绿色建筑材料秸秆钢渣泡沫混凝土研究现状及展望

秸秆钢渣泡沫混凝土是新型的绿色建筑材料,融合秸秆纤维和钢渣粉末,辅以水泥和泡沫,以提升强度和环境性能。研究集中在性能提升、生产工艺优化和环境适应性增强,同时探索高效环保的制备工艺。面临的挑战包括提升强度与耐久性、热稳定性和隔音性能,以及原料混合和泡沫稳定性、一致性的优化。环境影响考量涉及秸秆和钢渣的利用。应对策略包括材料性能改善、工艺优化和环境影响减缓,同时展望了高性能和多功能一体化应用的未来研究方向、市场潜力和发展趋势。

废弃加气混凝土综合利用研究现状及展望

为探明加气混凝土综合利用现状,研究考察了废弃加气混凝土综合利用现状,通过探讨其物理和化学特性,展示了废弃加气混凝土的环境问题,重点研究废弃加气混凝土的应用技术及工程应用研究现状。研究结果表明:物理和化学的综合利用技术有助于减轻建筑废弃物对环境的影响,降低新建筑项目的材料成本,有助于建筑业的绿色转型,在促进建筑行业可持续发展方面有较大潜力,未来的研究应关注提高回收材料性能的新方法,以实现建筑行业的可持续发展。研究结果可为废弃加气混凝土的综合利用研究及工程应用提供参考。

绿色高性能混凝土最佳配合比研究

聚焦绿色高性能混凝土(Green High Performance Concrete,GHPC)的最佳配合比,旨在实现保持卓越性能的同时最大限度地利用工业废渣,如粉煤灰、超细矿渣、硅灰等。通过深入研究最佳配合比,能够精确调控GHPC的工作性能、强度和耐久性,以满足可持续建筑的标准。研究采用了贝叶斯算法优化后的高斯过程回归模型,通过125组试验结果进行训练,最终确定了FL 11%、SF 0%、SL 16%的最佳混合比。通过对比预测与试验结果,验证了模型的可靠性,误差控制在2%以内。该研究为GHPC的配合比提供了科学依据,为推动环保建筑材料的可持续发展提供了实用的指导。

高性能混凝土在交通工程中的应用

高性能混凝土(HPC)正重新定义交通工程的质量和可靠性标准。在北京大兴国际机场和上海杨浦大桥等关键项目中,HPC不仅证明了自身作为一种革命性材料的价值,而且展示了其在提升工程结构强度、耐久性和环境适应性方面的显著优势。这些特性不仅降低了长期维护成本,还为现代交通基础设施的设计和建设提供了新的可能性,推动了整个行业向着更经济、环保和可持续的方向发展。HPC的成功应用案例突出了其在应对现代工程挑战中的关键作用,预示着其在未来建筑材料领域的广泛应用前景。

水工大体积混凝土中低热水泥的应用研究

由于具有早期水化低热的特点,实际工程中使用低热硅酸盐水泥大多表现出优异的抗裂性能。文章利用亚微观和宏观试验,探讨了低热水泥混凝土的水化热、绝热温升、抗压强度和自收缩变形性能。结果表明:低热水泥的水化速率和水化热更低,混凝土具有更低的绝热温升值及更好的体积稳定性,表现出后期强度增长率高而早期强度较低的特点,可以增强大坝主体结构抗裂性能,对水工大体积混凝土具有较好适用性。