Phosphogypsum as a Component of Flowable Fill

1996 ◽  
Vol 1546 (1) ◽  
pp. 79-87
Author(s):  
S. Gandham ◽  
R. K. Seals ◽  
Paul T. Foxworthy
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Unconfined Compressive Strength ◽  
Preliminary Test ◽  
Flowable Fill ◽  
Final Design ◽  
Potential Component ◽  
Class C ◽  
The Individual ◽  
Minimal Environmental Impact

Phosphogypsum (PG) is a by-product of the production of phosphoric acid, a key ingredient in the manufacture of fertilizers. Large amounts of PG have been stockpiled in Florida, Louisiana, and Texas, as well as other parts of the world. The means of using and disposing of this by-product with minimal environmental impact have been developed in research spanning almost 20 years. A study was conducted to investigate PG as a potential component of flowable fill materials along with Class C fly ash. Both Class F and Class C fly ashes have been used successfully to provide flowability and strength characteristics to flowable fill. A number of mix proportions of PG and fly ash were tested for flowability, time of setting, and unconfined compressive strength in a preliminary test series. Using the results of these preliminary tests, three final design mixtures were developed. These mixtures were then subjected to different physical and engineering property tests, including flowability, time of setting, unconfined compressive strength, flexural strength, dimensional stability, and permeability. Tests were also conducted to evaluate the environmental effects of the individual mixtures. These tests included the toxicity characteristic leaching procedure and radon emission testing. The results of this study indicated that PG can be used successfully as a component of flowable fill.

Mix Design for Flowable Fill

1997 ◽  
Vol 1589 (1) ◽  
pp. 26-28 ◽  
Author(s):  
S. T. Bhat ◽  
C. W. Lovell
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Ultimate Strength ◽  
Coal Combustion ◽  
Unconfined Compressive Strength ◽  
Mix Design ◽  
Target Strength ◽  
Fresh Material ◽  
Flowable Fill ◽  
Strength Material

The grout-like material called flowable fill has experienced new popularity, particularly the controlled low-strength material variety, which is easily excavated. The properties ordinarily desired of the mix are: (a) flow under gravity; (b) hardening for early walkability and cover; and (c) ultimate strength low enough to allow ready excavation. Flowability of fresh material is evaluated in a simple spread test. Hardening is measured by a mortar penetrometer, and these values are correlated with unconfined compressive strength. It is desirable to keep the ultimate strength to less than 1 035 kPa (150 lbf/in.2); somewhat less target strength is selected for the 28-day value. Mix design is empirical, but the time and expense required may be reduced by following a rational and logical procedure, which is described. The materials emphasized in this paper are Class F coal combustion fly ash and waste sands from greensand ferrous castings.

scholarly journals A Comparative Study on the Effect of Class C and Class F Fly Ashes on Geotechnical Properties of High-Plasticity Clay

CivilEng ◽  
2021 ◽  
Vol 2 (4) ◽  
pp. 1009-1018
Author(s):  
Salar Shirkhanloo ◽  
Mohammad Najafi ◽  
Vinayak Kaushal ◽  
Mehrdad Rajabi
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Unconfined Compressive Strength ◽  
Geotechnical Properties ◽  
Dry Density ◽  
High Plasticity ◽  
Fly Ashes ◽  
High Plasticity Clay ◽  
Class C ◽  
Class F

Clays generally have a low strength and capacity, and additives are usually used to stabilize them. In recent years, using fly ash to stabilize soil has decreased environmental pollution while also having an economic benefit. The objective of this study is to perform a comparative investigation on the effect of class C and class F fly ashes on geotechnical properties of high-plasticity clay using the Atterberg’s limit, compaction, California Bearing Ratio (CBR), and unconfined compressive strength tests. The results showed that with an increase in the amount of fly ash, there was a decrease in the maximum dry density and an increase in the optimum moisture content. Moreover, an addition of fly ashes of up to 25% caused a reduction of the liquid limit and plasticity index, and an increase in the maximum unconfined compressive strength and CBR. Lengthening the curing time had a positive impact on the unconfined compressive strength of the soil. The soil samples with class C fly ash were seen to possess more efficient geotechnical properties as compared to class F fly ash.

scholarly journals Characterization and Comparison Research on Composite of Alluvial Clayey Soil Modified with Fine Aggregates of Construction Waste and Fly Ash

2021 ◽  
Vol 28 (1) ◽  
pp. 83-95
Author(s):  
Qu Jili ◽  
Wang Junfeng ◽  
Batugin Andrian ◽  
Zhu Hao
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Unconfined Compressive Strength ◽  
Clayey Soil ◽  
Dry Density ◽  
Maximum Dry Density ◽  
Construction Waste ◽  
Comparison Research ◽  
Fine Aggregates ◽  
Optimum Water Content

Abstract Fine aggregates of construction waste and fly ash were selected as additives to modify the characteristics of Shanghai clayey soil as a composite. The laboratory tests on consistency index, maximum dry density, and unconfined compressive strength were carried out mainly for the purpose of comparing the modifying effect on the composite from fine aggregates of construction waste with that from fly ash. It is mainly concluded from test results that the liquid and plastic limit of the composites increase with the content of two additives. But their maximum dry density all decreases with the additive content. However, fine aggregates of construction waste can increase the optimum water content of the composites, while fly ash on the contrary. Finally, although the two additive all can increase the unconfined compressive strength of composites, fly ash has better effect. The current conclusions are also compared with previous studies, which indicates that the current research results are not completely the same as those from other researchers.

STRENGTH OF CONCRETE MORTAR PREPARED BY PARTIAL SUBSTITUTION OF CEMENT WITH RECYCLED GLASS POWDER

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Pranshoo Solanki ◽  
Harsh Chauhan
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Crucial Role ◽  
Glass Powder ◽  
Partial Substitution ◽  
Recycled Glass ◽  
Mortar Strength ◽  
Waste Glass Powder ◽  
Flowable Fill

This experiment was conducted to determine the utility of substituting cement with the recycled glass powder (RGP) in mortar mixtures. A total of 21 mortar mixtures were produced using various RGP (FG) ratios (CG), and fly ash (FA) powders. The mortar mixtures were used to prepare cubes which were tested for 7-and 28-day compressive strength. The substitution of cement with FG and CG in mortar resulted in reduced 7-and 28-day compressive strength values. However, the amount and type of RGP substituted for cement plays a crucial role in the determination of mortar strength. Above contraction in compressive strength was observed at an initial maturity than at the final maturity. Further, replacement of cement with Fly Ash showed increase in compressive strength up to certain content. More research and testing for the optimal percentage and size of waste glass powder that can be used is required in flowable fill.

scholarly journals Experimental study on the properties of highperformance concrete made with class C fly ash

2019 ◽  
Vol 276 ◽  
pp. 01014
Author(s):  
I Made Alit Karyawan Salain ◽  
I Nyoman Sutarja ◽  
Teguh Arifmawan Sudhiarta
Keyword(s):  
Experimental Study ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Fly Ash ◽  
Permeability Coefficient ◽  
Splitting Tensile Strength ◽  
Type I ◽  
Fine Aggregate ◽  
Hydration Time ◽  
Class C

This experimental study presents the properties of highperformance concrete (HPC) made by partially replacing type I Portland cement (OPC) with class C fly ash (CFA). The purpose of this study is to examine, with hydration time, the development of the compressive strength, the splitting tensile strength and the permeability of HPC utilizing different quantity of CFA. Four HPC mixtures, C1, C2, C3, and C4, were made by utilizing respectively 10%, 20%, 30% and 40% of CFA as replacement of OPC, by weight. One control mixture, C0, was made with 0% CFA. The mix proportion of HPC was 1.00 binder: 1.67 fine aggregate: 2.15 coarse aggregate with water to binder ratio 0.32. In each mixture, it was added 5% silica fume and 0.6% superplasticizer of the weight of the binder. Tests of HPC properties were realized at the age of 1, 3, 7, 28, and 90 days. The results indicate that CFA used to partially replace OPC in HPC shows adequate cementitious and pozzolanic properties. The compressive strength and the splitting tensile strength of HPC increase while the permeability coefficient decreases with increasing hydration time. It is found that the optimum replacement of OPC with CFA is 10%, however the replacement up to 20% is still acceptable to produce HPC having practically similar harden properties with control mixture. At this optimum replacement and after 90 days of hydration, the compressive strength, the splitting tensile strength and the permeability coefficient can reach 68.9 MPa, 8.3 MPa and 4.6 E-11 cm/sec respectively. These results are 109%, 101%, and 48% respectively of those of control mixture.

scholarly journals Fly Ash-Based Geopolymer Building Materials for Green and Sustainable Development

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5699
Author(s):  
Rosicky Methode Kalombe ◽  
Victor Tunde Ojumu ◽  
Chuks Paul Eze ◽  
Sammy Mwasaha Nyale ◽  
John Kevern ◽  
...  
Keyword(s):  
Sustainable Development ◽  
Compressive Strength ◽  
Fly Ash ◽  
Environmental Impact ◽  
Co2 Emissions ◽  
Building Materials ◽  
Curing Conditions ◽  
High Alkalinity ◽  
Series Of Experiments ◽  
Minimal Environmental Impact

This study reports on formulations and conditions for producing fly ash-based geopolymers with a view to showing that the compressive strength required for construction applications can be obtained without the addition of aggregates, sand, and/or cement. It was shown in a series of experiments constituting at least 73% fly ash that a compressive strength of up to 90 MPa can be obtained depending on the curing conditions. While high alkalinity resulted in stronger materials, the results showed about 40% savings in CO2 emissions without using sand and cement. Such materials are suited for construction applications with minimal environmental impact.

Effect of Partial Replacement of Fly Ash by Metakaolin on Strength Development of Fly Ash Based Geopolymer Mortar

2017 ◽  
Vol 744 ◽  
pp. 131-135 ◽  
Author(s):  
Muhammad Zahid ◽  
Nasir Shafiq ◽  
Mohd Fadhil Nuruddin ◽  
Ehsan Nikbakht ◽  
Asif Jalal
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Sodium Hydroxide Solution ◽  
Base Material ◽  
Sodium Silicate Solution ◽  
Silicate Solution ◽  
Partial Replacement ◽  
Strength Development ◽  
Class C ◽  
Class F

This article aims to investigate the compressive strength variation by the addition of metakaolin as a substitute of fly ash in the fly ash based geopolymer mortar. Five, ten and fifteen percent by weight of fly ash was replaced by highly reactive metakaolin. Two type of fly ashes namely, ASTM class F and ASTM class C were used as a base material for the synthesis of geopolymer mortar. Eight molar sodium hydroxide solution mixed with sodium silicate solution was used as alkaline activator. For optimum geopolymerization, mortar was cured at sixty degree Celsius for twenty four hours duration. Results show different behavior of metakaolin replacement on compressive strength for two different types of fly ash based geopolymer mortar. Improvement in compressive strength was seen by addition of metakaolin in ASTM class F fly ash based geopolymer. On the other hand compressive strength was decreased abruptly in fly ash class C based geopolymer up to certain replacement level.

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