Experimental Study on the Use of Trass as a Supplementary Cementitious Material in Pervious Concrete

Abstract： The purpose of this paper is to evaluate the suitability of using trass as a supplementary cementing material in pervious concrete. OPC （Ordinary Portland Cement） was replaced in the concrete mix by 15%, 25% and 35% weight percentages and the results were compared with reference mixtures with 100% Portland cement. The variables in this study were trass content, aggregate size and water to cement ratio. Sixteen eases of concrete mixtures were tested to study physical and mechanical properties of hardened concrete, including porosity, permeability, compressive strength, splitting-tensile strength and flexural strength at various ages. Results indicated that mechanical properties of the pervious concrete marginally decreased with the increased content of trass when compared to the reference mixtures. However, at later ages the differences were insignificant.

The Effect of Wet-grinding on the Properties of Glass Powder and Its Application in Cement Based Materials

To improve the pozzolanic reactivity,waste glass(WG)needs to be micronized to fine particles so as to expedite the leaching of active constituent.The key feature of this work is to examine the effect of wet-grinded WG on the mechanical and structural properties of cement based materials.The experimental results show that wet-grinding can improve the ions leaching behavior of WGP and decrease the stability of silicon oxide bond.The pozzolanic reactivity of WGP was dramatically enhanced after wet-grinding,as high as 144.1%at 1 d and 110.9%at 28 d when the mean grain size of WGP reached 0.90μm.The ground WGP can promote the transformation of capillary pores to gel pores to improve the compactness of microstructure regardless of the reaction time.

The NMR core analyzing tomograph:a multi-functional tool for non-destructive testing of building materials

NMR is becoming increasingly popular for the investigation of building materials as it is a non-invasive technology that does not require any sample preparation nor causes damage to the material.Depending on the specific application it can offer insights into properties like porosity and spatial saturation degree as well as pore structure.Moreover it enables the determination of moisture transport properties and the(re-)distribution of internal moisture into different reservoirs or chemical phases upon damage and curing.However,as yet most investigations were carried out using devices originally either designed for geophysical applications or the analysis of rather homogeneous small scale(<10 mL)samples.This paper describes the capabilities of an NMR tomograph,which has been specifically optimized for the investigation of larger,heterogeneous building material samples(diameters of up to 72 mm,length of up to 700 mm)with a high flexibility due to interchangeable coils allowing for a high SNR and short echo times(50-80 ms).

Unveiling the Carbonation Behavior and Microstructural Changes of Magnesium Slag at 0℃

Magnesium slag(MS)is an industrial byproduct with high CO_(2)sequestration potential.This study investigates the carbonation behavior and microstructural changes of MS during wet carbonation at 0℃.XRD,TG,FTIR,SEM,and BET techniques were used to characterize the phase composition,microstructure,and porosity of MS samples carbonated for different durations.The results showed that the main carbonation products were calcite,vaterite,and highly polymerized silica gel,with particle sizes around 1μm.The low-temperature environment retarded the carbonation reaction rate and affected the morphology and crystallization of calcium carbonate.After 480 min of carbonation,the specific surface area and porosity of MS increased substantially by 740%and 144.6%,respectively,indicating improved reactivity.The microstructure of carbonated MS became denser with calcite particles surrounded by silica gel.This study demonstrates that wet carbonation of MS at 0℃significantly enhances its properties,creating an ultrafine supplementary cementitious material with considerable CO_(2)sequestration capacity.

Effect of Glass Powder on Concrete Sustainability

As defined by the American Concrete Institute (ACI), alternative supplementary cementitious materials (ASCMs) and local materials are very important in concrete sustainability. As an ASCM, glass powder (GP) shows excellent pozzolanic properties. This paper focuses on characterization and the effect of GP on concrete properties compared to those of Class F fly ash (FFA) and ground granulated blast furnace slag (GGBS). Concrete incorporating 0, 20 and 30% of GP and other concrete mixes containing 30% of FFA or GGBS were cast. The concrete mixes considered in this study have water to binder (w/b) mass ratio ranging from 0.35 to 0.65. The mechanical properties such as compressive strength and durability including chloride ions permeability and chloride ions diffusion are evaluated. The results show that GP develops effects on mechanical properties similar to those of FFA and performs better than GGBS and FFA in terms of permeability reduction. GP reduces dramatically chloride permeability of concrete regardless w/b ratio, favoring an improvement of the concrete durability. Because of the interesting permeability developed by concretes incorporating GP, its use as an ASCM is promising.

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).

Cracking behaviors and crack control of self-consolidating concrete: a review of literature

Cracking in concrete occurs from volumetric instability, mechanical loading, and/or environmental attack. Compared to conventional vibrated concrete, self-consolidating concrete often has a higher susceptibility to crack due to different mixture design, material properties and construction practices. To obtain a better understanding of self-consolidating concrete cracking behaviors for designing and constructing crack-controlled structural elements, reported current research and practices are reviewed and analyzed in this paper. It has been believed that when well designed and welt constructed, high quality self- consolidating concrete can be successfully used in various structures with cracks properly controlled.

Hydration Properties of Calcined Clay Pozzolan and Limestone Mineral Admixtures in Binary and Ternary Cements

This paper investigates the properties of hydrated binary and ternary blended cements using limestone and calcined clay pozzolan as supplementary cementitious materials. The blended cements were hydrated and their phase compositions were evaluated by thermogravimetric and powder X-ray diffraction at 28 days. The morphology of the samples was also determined. The water demand, setting time, compressive and flexural strengths of mortar and concrete samples were determined up to 365 days. The study concluded that the portlandite [Ca（OH）2] content was considerably reduced whilst ettfingite formation were enhanced as a result of admixture reactions. The water demand and setting times of blended cements were lower than OPC with 5% admixture content but higher with increasing content. The mechanical test results also showed that Class 42.5N and 32.5R cements can be produced from the binary and ternary blends containing up to 10% and 20% admixtures, respectively.

Influence of Selected Curing Techniques on Compressive Strength of Concrete From Palm Kernel Shell Ash and Ordinary Portland Cement

This paper discusses the findings of an experimental study on the effect of various curing procedures on the compressive strength of concrete pro­duced by partially substituting portland cement with Palm Kernel Shell Ash(PKSA).Palm kernel shell ash was utilized in a 1:2:4 mix ratio as a partial substitute for ordinary Portland cement(OPC)at percentage levels of 0%,10%,and 15%.River sand with particles passing a 4.75 mm BS sieve was used,as well as crushed aggregate with a maximum size of 20 mm,and palm kernel shell ash with particles passing a 212μm sieve.The compressive strength of the test cubes(150 mm × 150 mm × 150 mm)was determined after 7,28,and 56 days of curing.The results demonstrated that test cubes containing Palm kernel shell ash developed strength over a longer curing period than ordinary Portland cement concrete samples and that the strength changes depending on the amount of PKSA in the cube samples.The findings showed that at 28 days,test cubes with 5%,10%,and 15%PKSA content in all curing procedures utilized obtained a greater compressive strength.Curing by immersion produced the highest compres­sive strength in all replacement level while the concrete cured by sprinkling and spraying gives a lower strength in all replacement level.

Biochar as construction materials for achieving carbon neutrality

Biochar is a waste-derived material that can sequester carbon at a large scale.The development of low-carbon and sustainable biochar-enhanced construction materials has attracted extensive interest.Biochar,having a porous nature and highly functionalised surface,can provide nucleation sites for chemical reactions and exhibit compatibility with cement,asphalt,and polymer materials.This study critically reviewed the state-of-the-art biochar-enhanced construction materials,including biochar-cement composites,biochar-asphalt composites,biochar-plastic composites,etc.The efficacies and mechanisms of biochar as construction materials were articulated to improve their functional properties.This critical review highlighted the roles of biochar in cement hydration,surface functional groups of engineered biochar for promoting chemical reactions,and value-added merits of biochar-enhanced construction materials(such as humidity regulation,thermal insulation,noise reduction,air/water purification,electromagnetic shielding,and self-sensing).The major properties of biochar are correlated to the features and functionalities of biochar-enhanced construction materials.Further advances in our understanding of biochar’s roles in various composites can foster the next-generation design of carbon-neutral construction materials.

THE ROAD TO PLATINUM Using the USGBC’s LEED-EB® Green Building Rating System to Retrofit the U.S. Environmental Protection Agency’s Region 10 Park Place Office Building

According to the U.S.Green Building Council(USGBC),buildings account for a significant amount of environmental degradation.The building sector is the number one producer of global CO_(2) emissions in the U.S.,followed by the transportation and industrial sectors.1(See Figure 1 for the environmental impact of all U.S.buildings.)The concept of green buildings represents a major paradigm shift in the architectural,construction,and engineering fields.As society increasingly switches its appreciation of buildings from merely size and aesthetics toward environmental stewardship and efficiency,the USGBC’s LEED Green Building Rating System has become increasingly popular to follow.Since its inception in 2000,the LEED system has been promoting and monitoring green building practices throughout the United States.With a four-tiered rating scheme including LEED Certified,LEED Silver,LEED Gold,and LEED Platinum,the system currently has 35,000 projects already on their way toward certification.2 In particular,the LEED for Existing Buildings(LEED-EB)system looks to retrofit existing buildings into those that are more sustainable,efficient,and environmentally friendly.Doing so significantly reduces the demand for new resources,as construction managers can recycle and reuse building materials and incorporate them into new designs.This truly is the definition of green building and is the way of the future.By implementing green building practices,many of the adverse environmental impacts of buildings can be dramatically reduced,often for only a one to two percent initial cost premium over the price of conventional construction practice.3 Several environmental benefits of green buildings include improving air and water quality,conserving natural resources,and becoming more energy efficient.Sudies have shown that green buildings,compared to normal buildings,can reduce energy use by 24–50 percent,CO_(2) emissions by 33–39 percent,water use by 40 percent,and solid waste by 70 percent.4(See Figure 2 for the impact of green commercial buildings compared to the average commercial building.)In fact,if half of all new construction within the U.S.were built to match these percentages,it would be the equivalent of taking more than one million cars off of the road every year.5 Economic benefits include reducing operating costs,improving employee productivity and satisfaction,and optimizing economic performance over the life cycle of the structure.6 Additionally,health and community benefits include enhancing occupant comfort and health,and contributing to an overall positive environmentallyconscious reputation.7 Furthermore,Taryn Holowka states,“people in green buildings have 40-60 percent fewer incidents of colds,flu,and asthma;patients in green hospitals are discharged as much as two and a half days earlier;and kids in green schools increase their test scores by as much as 18 percent.”8 The U.S.EPA’s Region 10 Park Place office building in Seattle was built in 1970.Its owner,Washington Holdings,and building manager,Wright Runstad&Company,have been encouraged by the EPA to use innovative energy conservation design,water conservation,waste reduction,stormwater management,and other strategies to make the structure more sustainable.Following the EPA’s Green Building Strategy,which states that the EPA aims to strengthen the foundations of green building and raise public awareness of building-related impacts and opportunities,the Park Place building has become only the fifteenth LEED-EB Platinum building in the world,and one of the most impressive nearly-forty-year-old buildings in the entire United States.By using the LEED-EB Platinum green building rating system,the Park Place building management team has been able to successfully lower the building’s energy consumption rate,improve its water efficiency,and make many other beneficial changes—all of which demonstrate just how effective the LEED system is at producing higher performance buildings.