Reduction In Cement Content Research Articles

Influence of Oil Palm Biomass Waste on Compressive Strength and Chloride Penetration of Mortar

The utilization of waste materials which are abundant and cheap, especially from clean resources, has become more pressing than ever. This study investigates the influence of Oil Palm Biomass waste including the Palm Oil Fuel Ash (POFA), Oil Palm Kernel Shell (OPKS) and Oil Palm Fibre (OPF) on the compressive strength and chloride penetration of mortar. The POFA was used as cement replacement up to 80% in nano size. The mass ratio of fine aggregates to binder was 3:1. Test specimens 70×70×70 mm cube were prepared and cured in water for 28 days. Ordinary Portland cement (OPC) mortar was also prepared as control specimen. The specimens were immersed in Sodium Chloride solution up to 18 months. The evaluation was done by visual observation, ultrasonic pulse velocity and mass change before and after exposure. The mortar was then split into two and sprayed with 0.1N Silver Nitrate solution to see the depth of penetration. The test results revealed that biomass mortar showed high resistance to chloride penetration as compared to OPC mortar due to the reduction of cement content in the mixture. Besides, the reactive silica from nano POFA produced more crystalline formation thus, reduced the porosity and crack within the biomass mortar.

Influence of bacteria on compressive strength and permeation properties of concrete made with cement baghouse filter dust

The present study investigated the influence of cement baghouse filter dust (CBFD) in control and bacterial concrete, as partial replacement of ordinary Portland cement (0%, 10%, 20% and 30%) on compressive strength, water absorption, porosity, chloride permeability and sorptivity at 28 and 56days of curing. Calcite producing bacterial strain AKKR5 was mixed in water during concrete mixing with the cell concentration of 105cells/mL. X-ray diffraction analysis confirmed the calcite production by bacterial strain. Control and bacterial concrete with 0% CBFD achieved best results for compressive strength of 32.89 and 34.66N/mm2, respectively, but with increasing the percentage of CBPD the compressive strength was decreased. Water absorption was significantly reduced in bacterial concrete compared to control concrete. The chloride permeability of concrete specimens containing control and bacterial CBFD concrete showed “moderate” to “low” permeability except 30% CBFD concrete with increasing curing period from 28 to 56days. SEM and XRD results exhibited formation of ettringite in pores, increased calcium silicate hydrate (CSH) and calcite production which densified the concrete structure, and thus, increased the compressive strength in bacterial concrete containing CBFD. It was also found that CBFD is not cementitious in nature and replacing it with cement will reduce cement content. At 28days, concrete mixture containing 10% CBFD exhibited compressive strength equivalent to target strength of 28N/mm2 required for designed control mix.

Electric Arc Furnace Slag as Coarse Recycled Aggregate for Concrete Production

Electric arc furnace (EAF) slag is a by-product of steel production in electric arc furnaces. Several studies have tried to demonstrate its suitability in civil engineering application, such as in bituminous mixtures and cement-based materials, due to its good physical, chemical and mineralogical properties. Particularly the re-use as coarse aggregate for concrete production has been shown to be a promising valorisation, when physical and chemical stability is guaranteed. Additionally, EAF slag's high mechanical strength makes it suitable for high-performance concrete production. In this work three EAF concretes, with various cement content and also with silica fume addition, were compared with a reference concrete, to identify a convenient mix design to reach a concrete strength class between C50/60 and C60/75. Mechanical strength was evaluated analysing compressive and tensile strength, and elastic modulus. A complementary microstructural analysis was performed after the failure of the specimens, with the aim of analysing the morphology of the interfacial transition zone. Results indicate that the use of EAF slag in concrete allows reaching higher compressive strength than with coarse natural aggregates. EAF slag application in structural concrete promotes also the reduction of cement content in the mix to reach the same strength class.

RETRACTED: Comparative study on effects of Class F fly ash, nano silica and silica fume on properties of high performance self compacting concrete

Abstract This paper presents the effects of some admixtures including silica nanoparticles, silica fume and Class F fly ash on different properties of high performance self compacting concrete (HPSCC). For this purpose, a fraction of Portland cement with the aim of cement content reduction was replaced different fractions of pozzolanic admixtures. The rheological properties of fresh concrete were observed through slump flow time and diameter and V-funnel flow time. Thermal properties were investigated via thermogravimetric analysis (TGA) test. Transport properties evaluated by water absorption, capillary absorption and chloride ion penetration tests. The results indicated that increase of fly ash content improves the rheological properties of HPSCC. The results also showed that mechanical and transport properties improved in the mixtures containing admixtures especially blend of silica nanoparticles and silica fume. It can also be concluded that higher amount of mineral admixtures combined with small fractions of nanopowders could be promising technique toward high performance concrete as a key material along with energy saving in construction and building technology.

Design and performance of ternary blend high-volume fly ash concretes of moderate slump

One approach to increasing the sustainability of concrete construction is to replace a significant portion of the ordinary portland cement (OPC) with a supplementary cementitious material, such as fly ash. This paper presents mixture proportions and measured properties for a series of six high-volume fly ash (HVFA) concretes, five containing a ternary component of a fine limestone powder, with cement replacement levels of 40% or 60% by volume, targeting moderate slump (150mm) applications. Special emphasis is given to electrical resistivity measurements, comparing measurements conducted in a uniaxial vs. a surface configuration, and assessing the capability of measurements of the bulk resistance of the fresh concrete to anticipate setting times in these HVFA mixtures. The degree to which relationships exist between compressive strength and either cumulative heat release or uniaxial resistivity are presented. In general, ternary blend HVFA concretes can be formulated to provide acceptable strengths at both early ages and over the longer term, with an increased resistivity that implies an enhanced durability and increased service life. However, to achieve moderate slumps at the requisite lower water-to-cementitious material ratios, high dosages of high-range water-reducing admixtures (HWRA) will likely be required, which can negatively impact early-age properties (e.g., setting time and 1 d strengths). Thus, optimum mixture proportioning will require the careful selection and evaluation of the available HRWRA products, both individually and in potential combinations. Finally, another viable route to reducing cement content is to increase the aggregate volume fraction, as demonstrated by the OPC control concretes investigated in this study where aggregate volume fraction was increased from 70% to 72.5%, concurrently achieving a 10% reduction in cement content. In the ternary blend HVFA mixtures, further increases to 75% aggregates were possible, resulting in overall cement reductions (per unit volume of concrete) of between 45% and 63%.

Reduction of cement content in renderings with fine sanitary ware aggregates

The aim of this research is to present a viable solution for the reduction of cement content in mortars, by recycling a non-biodegradable material, such as grinded sanitary ware fines. This research analysed the reduction of cement content from a volumetric ratio of 1:4 (cement: aggregates) to 1:5 and 1:6 with simultaneous incorporation of fines from sanitary ware waste (SWW). The fines incorporated were below 149 μm and were incorporated as 20 % of the aggregates volume. Several tests were carried out in the fresh and hardened states, namely water retention, flexural and compressive strengths, water absorption by capillarity, permeability to water under pressure and to water vapour and dimensional instability. It was found that the reduction of cement content and incorporation of SWW allowed better performance on most of the tests than that of the reference mortar (1:4 ratio).

Deformation and mechanical properties of quaternary blended cements containing ground granulated blast furnace slag, fly ash and magnesia

Shrinkages of cementitious materials may lead to cracking under restrained conditions. This study was motivated to develop non-shrinkage quaternary blended cements through blending slag and fly ash with Portland cement containing reactive MgO. The hydration process, autogenous shrinkage at early age, long-term volume deformation, mechanical properties, and microstructure of cement specimens were investigated. Results showed that the autogenous shrinkage of the cement pastes was effectively mitigated due to the compensation of the MgO present and the reduction of cement content owing to the partial replacements with slag and fly ash. The mechanical strengths of the blended cement mortars were lower than that of the corresponding plain Portland cement mortars at early age of 3d, but increased significantly to be similar or higher at late ages of 28d and 90d. This is attributed to the microstructure densification and the interface microstructure enhancement due to the reaction of SCMs with clinker phases.

A Case Study of Low Compressive Strength of Concrete Containing Fly Ash in East Java Indonesia

The utilization of fly ash (FA) into concrete has become a common practice in ready mix concrete production throughout the world, including Indonesia. The inclusion of this by product material into concrete has two main advantages: decreasing cost of material by reducing cement content and reducing waste produced from power plant operation. Despite almost two decades of experience and application, low compressive strength of concrete containing FA often occurs in construction projects in Indonesia. This paper describes one case of low compressive strength of concrete containing FA in a project located in East Java. During project construction, it was found from routine compressive test of concrete cylinders that the 28 days design strength was not achieved. Steps and measure taken following this incident are fully described. Non-destructive and destructive concrete test were employed to gain more data from concrete structures already casted with this mixture. Finally, possible cause of low compressive strength are identified and solutions are given to solve this problem.

Low Cost Ultra-High Performance Fiber Reinforced Concrete (UHPFRC) with Flash Metakaolin

Ultra-High Performance Fiber Reinforced Concrete (UHPFRC) presents remarkable mechanical and durability properties. Concretes can be considered as UHPFRC when compressive strength and direct tensile strength reach respectively reach 150 MPa and at 7 MPa at 28 days [1]. The UHPFRC matrix is generally composed by a high amount of cement and silica fume as binder, steel fibers, very low Water/Binder (W/B) ratio and high rang water reducer. Special heat treatment is often required in order to achieve compressive strengths over 150-200 MPa. This work focuses on the development of low cost UHPFRC with less energy in production process in order to widespread its use. To reach this objective, some mix criteria have been set up: use of local materials, substitution of silica fume by less expensive and more available flash metakaolin, reduced cement content, without heat treatment. Four UHPFRC mixtures have been fixed. The reference one incorporates silica fume. In the second one, metakaolin substitutes weight by weight silica fume. Two other mixtures have been designed using a wet packing method [2] and a metakaolin water absorption test [3], in order to optimize the metakaolin/cement mass ratio and to reduce cement content. Workability and mechanical tests have been carried out. Results show that the weight by weight substitution of silica fume by flash metakaolin leads to a slight reduction (about 5%) of strengths but a more important reduction of cost (about 10% of UHPFRC material cost per m3). The optimization of metakaolin/cement ratio allows reaching equivalent performances of silica fume reference mix and reducing cement content without significant strengths decrease.

Recycling of Glass Wastes in Latvia – Its Application as Cement Substitute in Self-Compacting Concrete

The rate of treated waste glass within the last 10 years has risen up to 25% due to improved waste glass collecting system in Latvia, however the glass waste recycling infrastructure is still up to date issue due to absence of local recycling companies. Application of glass wastes as cement substitute has significant effect on the properties of concrete making it eco-friendly construction material with several benefits like: decrease of accumulated glass wastes in landfills, the reduction of non-renewable natural resource consumption, the reduction of cement content up to 20-30% and the reduction of greenhouse gas emission. In the present investigation was evaluated the effectiveness of ground soda-alkaline earth-silicate glass coming from low pressure mercury-discharge lamp waste chips, borosilicate glass coming from incandescent light bulb waste chips, soda-lime glass cullet coming from beverage containers on workability, compressive strength and frost resistance of self-compacting concrete. DOI: http://dx.doi.org/10.5755/j01.sace.6.1.6127

High Efficiency Ecological Concrete

Waste glass is cementitious in nature when it is finely ground, and especially when it is ground in a wet environment it can be finer than Portland cement. The obtained borosilicate lamp waste glass slurry with a grain size of 0.713 – 8.088 μm has shown better fineness and stability to segregation in comparison to soda-lime and soda-alkaline earth-silicate waste glasses. Elaborated high efficiency concrete with borosilicate lamp waste glass showed 120 MPa compressive strength at 28 days and it can be considered as ecological due to reduced cement content for 20% in concrete mixture without changing concrete properties in a negative way, reduced CO2 and waste glass deposits.

C12A7계(系) 슬래그를 사용(使用)한 수축저감제(收縮低減劑)의 혼합재(混合材) 함량(含量)에 따른 특성(特性)

본 연구에서는 수축저감 효과를 높이고, 강도를 증진시키기 위해 <TEX>$C_{12}A_7$</TEX>계 슬래그를 사용한 수축저감제 및 이를 이용한 모르타르를 제조하였다. 또한 시멘트 사용량을 줄이기 위해, 플라이애쉬와 고로슬래그의 함량을 변화시킨 모르타르의 응결시간, 플로우, 압축강도를 측정하였다. 플라이애쉬와 고로슬래그 함량이 증가할수록 플로우 값이 증가하였고, 응결시간이 지연되는 것을 확인할 수 있었다. 또한 혼합재 함량 증가에 따라 초기재령에서는 압축강도가 낮아지지만, 장기재령에서는 높은 압축강도 값을 나타내었다. In this Study, it was fabricated that shrinkage reducing agent and mortar used <TEX>$C_{12}A_7$</TEX>-based slag enhanced the shrinkage reduction and compressive strength. To reduce cement content, setting time, flow and compressive strength of mortar with varying content of fly ash and blast furnace slag were experimented. The flow increased and setting time delayed as the increase of fly ash and blast furnace slag content. And early strength was lower and long age strength was higher than that of mortar with low content of admixture.

Mix Design for Pervious Recycled Aggregate Concrete

Pervious concrete is a tailored-property concrete with high water permeability which allow the passage of water to flow through easily through the existing interconnected large pore structure. This paper reports the results of an experimental investigation into the development of pervious concrete with reduced cement content and recycled concrete aggregate for sustainable permeable pavement construction. High fineness ground granulated blast furnace slag was used to replace up to 70 % cement by weight. The properties of the pervious concrete were evaluated by determining the compressive strength at 7 and 28 days, void content and water permeability under falling head. The compressive strength of pervious concrete increased with a reduction in the maximum aggregate size from 20 to 13 mm. The relationship between 28-day compressive strength and porosity for pervious concrete was adversely affected by the use of recycled concrete aggregate instead of natural aggregate. However, the binder materials type, age, aggregate size and test specimen shape had marginal effect on the strength–porosity relationship. The results also showed that the water permeability of pervious concrete is primarily influenced by the porosity and not affected by the use of recycled concrete aggregate in place of natural aggregate. The empirical inter-relationships developed among porosity, compressive strength and water permeability could be used in the mix design of pervious concrete with either natural or recycled concrete aggregates to meet the specification requirements of compressive strength and water permeability.

Reducing Set Retardation in High-Volume Fly Ash Mixtures with the Use of Limestone

High-volume fly ash (HVFA) concretes are attractive not only because they reduce cement content and the associated greenhouse gases, but also because they avoid landfilling excessive quantities of fly ash. These sustainability benefits are often tempered by practical constructability limitations that may exist for HVFA concretes: retardation and diminution of the early-age reaction, delay in setting (and finishing operations), and lower early-age strength. This paper explores the alleviation of these deficiencies in HVFA mixtures by the incorporation of fine limestone powders into ternary blends. Isothermal calorimetry and Vicat needle penetration measurements are employed to assess reaction rates and setting times, respectively. A systematic variation of the content and fineness of the limestone powder in mixtures containing either a Class C or a Class F fly ash indicates that setting times are linearly correlated with the surface area supplied by the limestone. Comparison of a limestone system to a system containing an inert titanium dioxide of similar particle size indicates that the acceleration and amplification effects of the limestone can be attributed to both physical (nucleation) and chemical (additional calcium ions) processes. The results indicate that ternary blends with 40% of the cement by volume replaced by 30% to 35% fly ash and 5% to 10% limestone at a constant water volume fraction can be achieved without significant delay in setting.

Using SP and SF to Lower Cement Content

In the present research, using different percents of superplasticizer (SP) and silica fume (SF) to improve the characteristics of concrete is performed. SP and SF are added to two types of normal concrete, the first is of mixing ratio (1:2:4) and the second is of mixing ratio (1:1.5:3).The results show that adding SF lead to increase compressive strength for first mix by about 45.3% and 47.7% while adding SP lead to increase the compressive strength by about 43% and 41% compared to reference mix at 7 and 28 day respectively. The corresponding values for second mix are 46.7%, 49%, 44% and 43% respectively.The maximum compressive strength when SP and SF used together can be attained when the percents of SF and SP are 5% and 3% respectively. The increase in compressive strength is about 49.3% and 48.4% for first mix, while the corresponding values for second mix are 52.4% and 51.2% as they compared to reference mix at 7 and 28 day respectively.For Tensile strength, adding SP lead to increase it by about 29.2% and 31.6% for first and second mix respectively, while the corresponding values when adding SF are 38.1% and 40.3%. The effect of using SP and SF together on increase tensile strength is more than the effect of using each one separately. The maximum tensile strength can be attained when the percent of SF and SP are 5% and 3% respectively as they increase the tensile strength by about 38.9% and 40.7% for first and second mix.The effect of using admixtures on cement content can be noted clearly as the maximum reduction percents are about 8.7% and 9.35% for first and second mix respectively when the percent of SP is 3%. The corresponding values are 9.4% and 11.26% when the percent of SF is 5%. Using SP and SF together at percent 3% and 5% respectively lead to reduce cement content by about 10.15% and 13.54% for first and second mix respectively.

Performance-based design and carbonation of concrete with high fly ash content

► A method is proposed to design concrete mixtures with low content of Portland cement . ► Portland cement is partially substituted by fly ash. ► The substitution of Portland cement results in CO2 emissions reduction. ► We studied the designed mixtures with a performance-based approach. ► The designed mixtures were found as resistant to carbonation as reference mixtures. This paper reports on an investigation of the durability of high-volume fly ash concrete exposed to carbonation (XC class in EN 206-1 Standard). The reduction of cement content is assumed to mitigate CO 2 emissions due to the production of Portland cement clinker. The durability of concrete is assessed through a performance-based approach. First, a performance-based method was applied to design a concrete mixture with more than 50% substitution of cement by fly ash. To cope with the high viscosity of the so-obtained mixture, an air-entraining agent was used. Due to its low cement content, the so-obtained mixture does not comply with the prescriptive requirements of the European standard (EN 206-1). Thus, according to the equivalent performance concept, its potential durability has to be proved through comparison with reference mixtures complying with prescriptive standard requirements. The performance-based evaluation of the durability of the designed mixture and reference mixtures (with Portland cement and blended cement) consisted in porosity and accelerated carbonation tests. The influence of curing mode and thermal treatment duration before carbonation test were also investigated. Whatever the curing mode, the designed mixture was found as resistant to accelerated carbonation as the reference mixture containing blended cement.

Optimization of cement and fly ash particle sizes to produce sustainable concretes

Abstract In the drive to produce more sustainable concretes, considerable emphasis has been placed on replacing cement in concrete mixtures with more sustainable materials, both from a raw materials cost and a CO2 footprint perspective. High volume fly ash concretes have been proposed as one potential approach for achieving substantial reductions in cement usage, but their usage is sometimes hampered by reduced early age strengths and dramatically increased setting times. One limitation of the current industry practice is that portland cements are generally only optimized for their performance in a pure cement, as opposed to a blended cement, system. In this paper, a new approach of optimizing the particle sizes of the cement and fly ash for achieving desired performance in a blended product will be presented. By appropriately selecting the particle size distributions of cement and fly ash, equivalent 1 d and 28 d strengths may be achieved with about a 35% volumetric replacement of cement with fly ash, while maintaining the same volume fraction of water in the mixture, thus providing an actual 35% reduction in cement content.

Optimizing Aggregates to Reduce Cement in Concrete without Reducing Quality

Of the constituents of concrete, cement is the most expensive and has the largest carbon footprint. High cement content in concrete affects the durability of concrete. Shrinkage in concrete generally increases with increase in cement content; however, increasing the aggregate content provides more volume stability. Cement content can be reduced with the proper selection of aggregates and use of admixtures. Two approaches are considered: (a) optimizing aggregate gradation by varying aggregate and paste content and (b) replacing cement with mineral fillers (microfines). For each mixture, the high-range water-reducing admixture dosage was adjusted to maintain a constant slump (workability). The effects on slump, compressive strength, drying shrinkage, permeability, and abrasion were measured. Results show that both methods can be used to reduce cement content, maintain or improve performance, and reduce cost, with a more sustainable concrete as the end result.

Improvement of the early-age reactivity of fly ash and blast furnace slag cementitious systems using limestone filler

This article analyzes the effects of the addition of limestone filler on the hydration rate, setting times and early-age mechanical properties of binary and ternary-binder mortars containing Portland cement, blast furnace slag (BFS) and fly ash (FA), with various substitution rates of cement with mineral additions going up to 50%. Vicat needle penetration tests and measurements of heat flow of reaction, compressive strength and dynamic Young’s modulus were carried out on 14 mortars prepared with binary and ternary binders, at 20°C. The results obtained on the mortars containing binary binders, show that their loss of mechanical strength at early age is not caused by a deceleration of the reactions of cement in the presence of mineral additions, but is mainly explained by the dilution effect related to the reduction in cement content. A moderate addition of limestone filler (8–17%) makes it possible to obtain ternary binders with early-age reactivity equal or even higher than that of Portland cement, and with 28-days mechanical resistance close to those of the binary-binder mortars. This accelerating effect of limestone filler is particularly sensitive in the case of mortars containing FA.

Design and evaluation of hydraulic lime grouts for the strengthening of stone masonry historic structures

The present paper discusses an experimental procedure realized in order to design hydraulic lime based grouts adequate for the strengthening of stone masonry historic structures. With the aim to minimize incompatibility problems between the original materials and the grouts, several natural hydraulic lime based grouts, as well as a ternary (lime–pozzolan–cement) grout with reduced cement content, have been studied. The selection of the most suitable grouts was performed based on a set of criteria, namely injectability, mechanical and durability characteristics. The selected grouts were subsequently injected into cylindrical specimens that simulate the infill of three-leaf stone masonry. The experimental results obtained from mechanical tests carried out on the injected cylinders demonstrated that all grout mixes studied within this work were efficient in strengthening the infill material; they exhibited, however, differences in terms of durability properties. Finally, an empirical formula was developed to predict the compressive strength of the injected infill, as a function of the mechanical properties of grouts.