scholarly journals Utilization of Iron Tailings Sand as an Environmentally Friendly Alternative to Natural River Sand in High-Strength Concrete: Shrinkage Characterization and Mitigation Strategies

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5614
Author(s):  
Zhiqiang Zhang ◽  
Zhilu Zhang ◽  
Shaoning Yin ◽  
Linwen Yu
Keyword(s):  
Iron Ore ◽  
Autogenous Shrinkage ◽  
Drying Shrinkage ◽  
High Strength ◽  
Mitigation Strategies ◽  
Fine Aggregate ◽  
River Sand ◽  
Super Absorbent Polymer ◽  
Iron Ore Tailings ◽  
Tailings Sand

The increasing annual emissions of iron ore tailings have proved a great threat to the natural environment, and the shortage of natural river sand, as well as the pursuit of sustainable development materials, provides motivation to reuse iron ore tailings as a fine aggregate in concrete. Due to the significantly different properties of iron tailings sand compared with natural river sand—such as the higher density, higher content of limestone particles smaller than 75 μm and its rough and angular shape—concretes prepared with iron tailings sand show remarkably higher shrinkage. This study presents the shrinkage characterization and shrinkage-reducing efficiency of three different methods on iron tailings, sand concrete and river sand concrete. The internal humidity was also monitored to reveal the shrinkage-reducing mechanism. The obtained results indicated that the autogenous and total shrinkage of iron tailings sand concrete were 9.8% and 13.3% higher than the river sand concrete at the age of 90 d, respectively. The shrinkage reducing agent (SRA) was the most effective shrinkage reducing method for river sand concrete, while for iron tailings sand concrete, super absorbent polymer (SAP) and controlled permeable formwork liner (CPFL) it worked best on autogenous shrinkage and drying shrinkage, respectively. Furthermore, the shrinkage mitigation strategies worked earlier for the drying shrinkage behavior of iron tailings sand concrete, while no such condition could be found for autogenous shrinkage.

scholarly journals Eliminating the Shrinkage of High Strength Concrete by using Super Absorbent Polymer (SAP)

2018 ◽  
Vol 11 (4) ◽  
pp. 8-13
Author(s):  
Baidaa Khdheer Ahmed
Keyword(s):  
Compressive Strength ◽  
High Strength Concrete ◽  
Autogenous Shrinkage ◽  
Drying Shrinkage ◽  
High Strength ◽  
Super Absorbent Polymer ◽  
Strength Concrete ◽  
Group A ◽  
Group B ◽  
Absorbent Polymer

High Strength Concrete (HSC) is one of the  most popular types of concrete used in the world. This type of concrete has a low rapid  hydration of cementation materials with low  w/cm and the external surrounding  environment condition exposed the HSC to  high autogenous shrinkage. If this shrinkage is  not treated well that well led to cracking, in  this case HSC need to convenient curing  necessary at the earliest time. This study  presents the use of Super Absorbent Polymer  (SAP) as internal curing agent to eliminate  shrinkage. Two types of shrinkage are tested in  this study (Autogenous shrinkage and drying  shrinkage).  Two groups of concrete mixes(A and B) are  studied in this study each group have five types  of concrete mixes, four mixes with high and  ultra-high compressive strength (RPC, MRPC, HSC and SCC) and the last one with normal  compressive strength (NSC). Group A  represent concrete mixes without SAP addition  and group B for concrete mixes with SAP.  SAP was added for all mixes at 0.3% by  weight of cement and adding 20ml water for  each gram of SAP, specimens with dimensions  (40*40*160) mm were used for testing  shrinkage for each mix with and without SAP,  average values for two specimens was taken as  a results. It was found that concrete mixes of  group B have lower shrinkage than the  shrinkage of concrete mixes in group A at 28  days age with reduction of autogenous  shrinkage(AS) of (57%, 35%, 37%, 44.5% and  37.5%) respectively and for drying shrinkage  the percentage of reduction was (89.5%, 72%,  82%, 70% and 71%) respectively, addition of  SAP to concrete mixes proves to have active  effect in reducing the shrinkage of concrete.

Study on Drying Shrinkage Properties of Concrete Using Blast Furnace Slag as Fine Aggregate

2012 ◽  
Vol 174-177 ◽  
pp. 539-544 ◽  
Author(s):  
Dong Sheng Shi ◽  
Zheng Ma ◽  
An Li Wu ◽  
Jing Bo Wang
Keyword(s):  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Drying Shrinkage ◽  
High Strength ◽  
Strength Level ◽  
Fine Aggregate ◽  
River Sand ◽  
High Strength Level ◽  
Four Levels ◽  
Furnace Slag

In this paper, the experiment about drying shrinkage of concrete using blast furnace slag as fine aggregate was introduced. In this experiment, blast furnace slag fine aggregates that were produced by two different steel factory and natural river sands that came from two different producing area were been used, and compressive strength of concrete for testing were four levels from ordinary strength level to high strength level. As results, the drying shrinkage of concrete that used blast furnace slag as fine aggregate is less than concrete that used natural river sand as fine aggregate when the mix proportion condition of concrete was identical. The relationship between drying shrinkage and age of drying of concrete that used blast furnace slag as fine aggregate could be described by same approximated curve equation that was used for the concrete using natural river sand as fine aggregate. As same as concrete using natural river sand, the drying shrinkage of concrete that used blast furnace slag as fine aggregate would decrease with decreasing of water cement ratio.

Experimental Application Study on Iron Ore Tailings in the Mortar

2017 ◽  
Vol 873 ◽  
pp. 203-207
Author(s):  
Ying Jie Chen ◽  
Ying Wei Song ◽  
Gen Li ◽  
Teng Teng ◽  
Jian Xun Yang
Keyword(s):  
Iron Ore ◽  
Production Costs ◽  
Engineering Properties ◽  
Resource Exploitation ◽  
Natural Sand ◽  
Application Study ◽  
Experimental Application ◽  
Iron Ore Tailings ◽  
Tailings Sand ◽  
Massive Development

The development of the national economy has been always depended on natural resources. The massive development of resource has resulted in large amounts of waste, and tailings sand is one of them. How to change waste into treasure, to solve the contradiction between environmental protection, energy supply and resource exploitation, more and more attention has been payed on it. This paper combined the development situation of iron ore tailings at home and abroad, based on its engineering properties, make it used in mortar. After replacing the cement and natural sand of mortar, we studied the influence on the engineering properties of mortar which are compressive strength, workability, and water consumption. The experimental results show that when the tailings ofreplacingratio is in a certain range, the adding tailings produce beneficial effect on the performance of mortar, whichcan meet the engineering requirements, save production costs, and improve economic efficiency.

scholarly journals Strength and Microstructure of Concrete with Iron Ore Tailings as Replacement for River Sand

2018 ◽  
Vol 34 ◽  
pp. 01003 ◽  
Author(s):  
Ali Umara Shettima ◽  
Yusof Ahmad ◽  
Mohd Warid Hussin ◽  
Nasiru Zakari Muhammad ◽  
Ogunbode Eziekel Babatude
Keyword(s):  
Iron Ore ◽  
Economic Value ◽  
Waste Product ◽  
Construction Materials ◽  
Sustainable Construction ◽  
Electron Microscopic ◽  
River Sand ◽  
Iron Ore Tailings ◽  
Concrete Production ◽  
And Performance

River Sand is one of the basic ingredients used in the production of concrete. Consequently, continuous consumption of sand in construction industry contributes significantly to depletion of natural resources. To achieve more sustainable construction materials, this paper reports the use of iron ore tailings (IOT) as replacement for river sand in concrete production. IOT is a waste product generated from the production of iron ore and disposed to land fill without any economic value. Concrete mixtures containing different amount of IOT were designed for grade C30 with water to cement ratio of 0.60. The percentage ratios of the river sand replacements by IOT were 25%, 50%, 75% and 100%. Concrete microstructure test namely, XRD and Field Emission Scanned Electron Microscopic/Energy dispersive X-ray Spectroscopy (FESEM/EDX) were conducted for control and IOT concretes in order to determine the interaction and performance of the concrete containing IOT. Test results indicated that the slump values of 130 mm and 80 to 110 mm were recorded for the control and IOT concretes respectively. The concrete sample of 50% IOT recorded the highest compressive strength of 37.7 MPa at 28 days, and the highest flexural strength of 5.5 MPa compared to 4.7 MPa for reference concrete. The texture of the IOT is rough and angular which was able to improve the strength of the concrete.

scholarly journals Predicting the drying shrinkage behavior of high strength portland cement mortar under the combined influence of fine aggregate and steel micro fiber

2017 ◽  
Vol 67 (326) ◽  
pp. 119 ◽  
Author(s):  
Zhengqi Li
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
Cement Mortar ◽  
Drying Shrinkage ◽  
High Strength ◽  
Fiber Content ◽  
Fine Aggregate ◽  
Aggregate Content ◽  
Normal Strength ◽  
Gardner Model

The workability, 28-day compressive strength and free drying shrinkage of a very high strength (121-142 MPa) steel micro fiber reinforced portland cement mortar were studied under a combined influence of fine aggregate content and fiber content. The test results showed that an increase in the fine aggregate content resulted in decreases in the workability, 28-day compressive strength and drying shrinkage of mortar at a fixed fiber content. An increase in the fiber content resulted in decreases in the workability and drying shrinkage of mortar, but an increase in the 28-day compressive strength of mortar at a fixed fine aggregate content. The modified Gardner model most accurately predicted the drying shrinkage development of the high strength mortars, followed by the Ross model and the ACI 209R-92 model. The Gardner model gave the least accurate prediction for it was developed based on a database of normal strength concrete.

scholarly journals Investigation on the Properties of Sustainable Reactive Powder Concrete by Utilization of Coir Pith Aggregates and Pyrogenic Silica

2021 ◽  
Author(s):  
Oorkalan A ◽  
Chithra S
Keyword(s):  
Silica Fume ◽  
Low Cost ◽  
Autogenous Shrinkage ◽  
Drying Shrinkage ◽  
Particle Packing ◽  
Reactive Powder Concrete ◽  
Fine Aggregate ◽  
Coir Pith ◽  
Pyrogenic Silica ◽  
Reactive Powder

Abstract The present study investigates the properties of RPC developed using low cost eco-friendly materials such as pyrogenic silica (PS) and coir pith (CP) fine aggregates. This study investigates the effects of PS as silica fume replacement which is the main constituent for the production of reactive powder concrete which contained coir pith as a fine aggregate replacement instead of quartz sand up to 25%. The use of silica fume increases the particle packing density of RPC but increases the shrinkage phenomenon in RPC due to the minimum w/b ratio adopted. Therefore, in this research PS is used as a partial substitute for SF up to 30% and its effect on the mechanical and durability properties of coir pith containing RPC is studied. The test results showed that the mechanical strength values decreased with an increase in the addition of CP aggregate beyond 5% whereas the decrement in compressive strength was partially reduced when PS is used as silica fume replacement up to a maximum of 30%. The chloride penetration resistance was also improved with increasing PS substitution in RPC containing CP aggregates. The autogenous shrinkage and drying shrinkage were also significantly reduced due to the internal curing ability of the CP aggregates in combination with PS. The development of dense CSH gels from hydration is also evident from low CaO/ SiO2 ratio obtained from the EDS analysis. Hence the combination of PS with CP aggregates can reduce the shrinkage characteristics of RPC thereby providing eco-friendly sustainable concrete at low cost.

scholarly journals Effect of Using River Sand on The Strength of Normal and High Strength Concrete

2018 ◽  
Vol 7 (4.20) ◽  
pp. 222 ◽  
Author(s):  
Haitham Al-Thairy
Keyword(s):  
High Strength Concrete ◽  
High Strength ◽  
Partial Replacement ◽  
Fine Aggregate ◽  
River Sand ◽  
Strength Concrete ◽  
Concrete Mixtures ◽  
Test Parameters ◽  
Normal Strength ◽  
Compressive And Flexural Strengths

The shortage and high cost of quarries sand in some regions around the world has motivated engineers and researchers to investigate the possibility and feasibility of using other materials to be used as a fine aggregate in concrete mixtures. The main objective of this research is to experimentally investigate the effect of using river sand as a partial replacement of the ordinary quarries sand on the mechanical properties of normal and high strength concrete. Nine concrete mixtures were prepared and tested in terms of fresh and hardened properties using different replacement ratios of the required proportion of the normal sand. Four replacement ratios were used for normal strength concrete (NSC) which are: 0%, 25%, 50% and 75%, whereas, five replacement ratios were used for high strength concrete (HSC) namely: 0%, 35%, 60% and 90%. For each strength grade, the test parameters of the prepared mixtures included compressive and tensile strength. The experimental test results have revealed that it is possible to obtain a normal and high strength concrete with acceptable compressive and flexural strengths values by using river sand with replacement ratios up to 25% and 35% for NSC and HSC, respectively. When the replacement ratios were increased to more than the aforementioned ratios, the strength of the concrete decreased accordingly.  

MECHANICAL PROPERTIES AND SHRINKAGE PROPERTIES OF THE CONCRETE WITH RECYCLED FINE AGGREGATE AND ADMIXTURE

2018 ◽  
Vol 5 (2) ◽  
Author(s):  
Yuji Nakata ◽  
Koji Takasu ◽  
Hidehiro Koyamada ◽  
Hiroki Suyama
Keyword(s):  
Compressive Strength ◽  
Pore Volume ◽  
Drying Shrinkage ◽  
High Strength ◽  
Recycled Aggregate ◽  
Fine Aggregate ◽  
Shrinkage Ratio ◽  
Recycled Fine Aggregate ◽  
High Durability ◽  
The Relationship

In Japan, it is forecasted that massive amounts of concrete waste material will be generated in the future as a result of demolition of many buildings, and expansion of the use of recycled aggregate is expected. In this study, it was verified the effect when relatively large amount of admixture is mixed, a combination of recycled fine aggregate of different quality and various admixtures, combination of each admixture in order to realize high strength and high durability by using recycled aggregate. The increase in the drying shrinkage ratio due to the deterioration of the recycled fine aggregate quality was larger than the fluctuation due to the admixture mixing ratio and the drying shrinkage ratio was distributed by forming a group for each quality of recycled fine aggregate. In the relationship between the pore volume and the compressive strength, when evaluated with pore volume of 2 μm or less in both cases, a good linear relationship could be confirmed. The relationship between the pore volume and the drying shrinkage rate was similar. Therefore, it was suggested that compressive strength and drying shrinkage ratio of mortar contained composite recycled fine aggregate and admixture could be predicted by evaluating with the pore volume of 2 μm or less.

scholarly journals Shrinkage Effects of Using Fly Ash instead of Fine Aggregate in Concrete Mixtures

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Dongsheng Zhang ◽  
Pengfei Han ◽  
Qiuning Yang ◽  
Mingjie Mao
Keyword(s):  
Fly Ash ◽  
Autogenous Shrinkage ◽  
Drying Shrinkage ◽  
Experimental Results ◽  
Fine Aggregate ◽  
Ordinary Concrete ◽  
Concrete Shrinkage ◽  
Substitution Level ◽  
Concrete Mixtures ◽  
Binder Ratio

China is the world’s largest emitter of fly ash, an industrial by-product of coal combustion. Motivated towards greener development, China’s engineering industries must determine how to effectively utilize this by-product, while ensuring environmental and public safety protections. This study investigated the use of fly ash instead of fine aggregate in concrete mixtures with a focus on concrete shrinkage. A series of experiments were performed in which fly ash substitution levels, water-binder ratios, and ambient humidities were each respectively and exclusively varied to determine changes in the concrete’s drying and autogenous shrinkages. Experimental results indicated that the substitution of fly ash consistently decreased the drying shrinkage relative to ordinary concrete; a substitution level of 25% optimally reduced the drying shrinkage by 20.81%. A substitution level of 15% decreased the autogenous shrinkage relative to ordinary concrete, whereas higher levels (25, 35, and 45%) increased it. Ambient humidities also affected the concrete shrinkage, but the water-to-binder ratio effects were negligible. Drying shrinkage largely occurred before 28 d, whereas autogenous shrinkage continued after 28 d. Based on these experimental results, we evaluated common theoretical shrinkage models and subsequently developed a modified shrinkage model for application to concrete containing fly ash as fine aggregate.

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