INVESTIGATION OF EFFECTS OF RECYCLED AGGREGATES AND BLAST FURNACE SLAG ON PROPERTIES OF SELF-COMPACTING CONCRETE

2020 ◽  
Vol XVII (3) ◽  
pp. 1-14
Author(s):  
Leila Shahryari ◽  
Maryam Nafisinia ◽  
Mohammad Hadi Fattahi

The effects of simultaneous use of recycled aggregates and ground blast furnace slag as a percentage of cement-constituting materials on different properties of fresh self-compacting concrete (SCC) are investigated in this study. To this end, three series of SCC mixtures with a fixed volume of cement paste equalling 380 ltr/m3 (2.36 gal/ft3) and the replacement ratio of coarse aggregates (fifty percent and one hundred percent) and total aggregates (zero percent, fifty percent and one hundred percent) were prepared. The water content ratios in the first, second and third series were 0.4, 0.45, and 0.5, respectively. The results of the compressive strength tests for 7-day, 14-day and 28-day cubic specimens and compressive strength and Brazilian test results for 28-day cylindrical specimens were used as control parameters governing the SCC resistive quality. The results of fresh SCC tests (including slump-flow and T50 tests, V-funnel test, and L-box test) showed that the negative effect of recycled fine aggregates on fresh SCC properties is significantly more than that of recycled coarse aggregate. However, recycled SCC with acceptable properties can be obtained with a slight increase in the amount of superplasticisers used in the presence of slag.

2020 ◽  
Vol 323 ◽  
pp. 01018
Author(s):  
Wei-Ting Lin ◽  
Lukáš Fiala ◽  
An Cheng ◽  
Michaela Petříková

In this study, the different proportions of co-fired fly ash and ground granulated blast-furnace slag were used to fully replace the cement as non-cement blended materials in a fixed water-cement ratio. The recycled fine aggregates were replaced with natural fine aggregates as 10%, 20%, 30%, 40% and 50%. The flowability, compressive strength, water absorption and scanning electron microscope observations were used as the engineered indices by adding different proportions of recycled fine aggregates. The test results indicated that the fluidity cannot be measured normally due to the increase in the proportion of recycled fine aggregates due to its higher absorbability. In the compressive strength test, the compressive strength decreased accordingly as the recycled fine aggregates increased due to the interface structure and the performance of recycled aggregates. The fine aggregates and other blended materials had poor cementation properties, resulting in a tendency for their compressive strength to decrease. However, the compressive strength can be controlled above 35 MPa of the green non-cement blended materials containing 20% recycled aggregates.


Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5879
Author(s):  
Sung-Ho Bae ◽  
Jae-In Lee ◽  
Se-Jin Choi

Recently, interest in environmentally friendly development has increased worldwide, especially in the construction industry. In this study, blast furnace slag powder (BFSP) and mixed steel fine aggregates were applied to cement mortars to reduce the environmental damage caused by the extraction of natural aggregate and to increase the recycling rate of steel by-products in the construction industry. We investigated the fluidity, compressive strength, tensile strength, accelerated carbonation depth, and chloride ion penetration resistance of mortars with steel slag aggregate and their dependence on the presence or absence of BFSP. Because the recycling rate of ferronickel slag is low and causes environmental problems, we considered mortar samples with mixed fine aggregates containing blast furnace slag fine aggregate (BSA) and ferronickel slag fine aggregate (FSA). The results showed that the 7-day compressive strength of a sample containing both 25% BSA and 25% FSA was nearly 14.8% higher than that of the control sample. This trend is likely due to the high density and angular shape of steel slag particles. The 56-day compressive strength of the sample with BFSP and 50% FSA was approximately 64.9 MPa, which was higher than that of other samples with BFSP. In addition, the chloride ion penetrability test result indicates that the use of BFSP has a greater effect than the use of steel slag aggregate on the chloride ion penetration resistance of mortar. Thus, the substitute rate of steel slag as aggregate can be substantially enhanced if BFSP and steel slag aggregate are used in an appropriate combination.


2020 ◽  
Vol 13 (2) ◽  
pp. 111
Author(s):  
Anni Susilowati ◽  
Pratikto Pratikto ◽  
Dennis Yudha Praditya ◽  
Kusno Wijayanto

Self Compacting Concrete (SCC) as one type of concrete that is mostly used in building construction has good workability and can be obtained by adding filler instead of cement. Ground Granulated Blast Furnace Slag (GGBFS) has a chemical composition similar to the content in cement. Therefore, the study of the use of GGBFS was used as a partial substitute for cement in the SCC to examine the influences and quality of GGBFS on fresh concrete and to obtain SCC with the best compressive strength. This research method uses an experimental method by making SCC concrete specimens with an initial fas of 0.4 according to ACI 211.4R-93. The specimens were worked using GGBFS levels of 0%, until 80%, and using 1,4% superplasticizer, and 2% accelerator by weight of cement. The use of GGBFS at SCC can increase the value of compressive strength of about 4,27%-25,64 compared to SCC without using GGBFS. The resulted are known that GGBFS can influence compression strength. Based on the testing of fresh and hard concrete, it concluded that the best quality of SCC used 20% of GGBFS.


2014 ◽  
Vol 627 ◽  
pp. 393-396
Author(s):  
Jun Hyoung Park ◽  
Jung Jun Park ◽  
Jae Heum Moon ◽  
Sung Wook Kim

This study investigates the effects of the compressive strength and area ratio of coarse aggregate of concrete for offshore construction on the erosion depth. To evaluate the erosion resistance of concrete, test was performed according to ASTM C 1138 using a plain mix with design strength of 30 MPa using only Portland cement and five other mixes including different quantities of fly ash and blast furnace slag. The test results showed that the erosion depth is influenced not only by the compressive strength but also by the area ratio of coarse aggregate.


2011 ◽  
Vol 250-253 ◽  
pp. 866-869 ◽  
Author(s):  
Hong Zhu Quan

To utilize the recycled powder as concrete additives, self-compaceing concerte with recycled powder, granulated blast-furnace slag and granulated limestone were tested for slump-flow, compressive strength, modulus of elasticity and drying shrinkage. Reduction in superplasticizing effect of high-range water reducer was found for concrete with recycled powder. Compressive strength of concrete with recycled powder were the same as those with granulated limestone, and lower than those with granulated blast-furnace slag. Concrete with recycled powder showed lower elastic modulus and higher drying shrinkage than those with granulated blast-furnace slag and granulated limestone. The addition of granulated blast-furnace slag together with recycled powder to self-compacting concrete improved superplasticizing effect of high-range water reducer and properties of concrete.


2019 ◽  
Vol 8 (4) ◽  
pp. 5045-5049

This paper enumerates strength gain efficiency of Rice Husk Ash (Rha) and Ground Granulated Blast Furnace Slag (Gbbfs) blend in Self-Compacting Concrete (SCC). From the precious studies carried by the authors it was observed that optimal use of Rha+Ggbfs in low and medium strength concretes imparts initial strengths and also later strengths. In low and medium strength SCC mixes, Ggbfs replaces OPC optimally (30%) and Rha replaces Ggbfs optimally (3%) but in case of high strength SCC mixes, RHA replacing Ggbfs does not offer the required workability or strength so instead of replacing Ggbfs by certain amount, Rha is added to the SCC. It was found that GGBFS does not yield the required workability so RHA is added to GGBFS based SCC. So after various trial mixes it was found that 25% GGBFS by weight of OPC and 5% RHA by weight of GGHFS is added to OPC. It was observed that 5% RHA addition to OPC made with 25% Ggbfs gives desired workability and strength. Due to addition of GGBFS to SCC will enhance the later age compressive strength but early age compressive strength decreases while the desired workability is controlled using SP appropriately. In M60 GGBFS+RHA based SCC, the strength increase at 3 days is nearly 33% and the compressive strength at 28 days decreased by 10%. Similarly tensile strength in a GGBFS and RHA admixed SCC increases by around 27% in M60 grade.


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