Influence of bagasse ash, calcium carbide residue and polyester fiber addition on shear strength of organic clay

A series of experiments including unconfined compression tests, three-axial tests, compaction tests, and split tensile tests were undertaken to investigate the influence of compaction parameters on the behaviour of bagasse ash-calcium carbide residue stabilized soil. A preliminary study on soil with the addition of 4%, 6%, 8%, 10%, and 12% calcium carbide residue established that the lime fixation point (LFP) was 4%. Then 9% bagasse ash was added to soil with 4% calcium carbide residue, and the cation exchanges and pozzolanic reactions were investigated. The addition of calcium carbide residue to bagasse ash stabilized soil caused short-term changes due to cation exchange reactions, including an increase in the friction angle and cohesion in the stabilized soil. In addition, due to the short-term reaction, the maximum stiffness in three-axial tests occurred in the samples moulded with less than their optimum moisture content (OMC), whereas the peak strength occurred in the samples moulded at their OMC. After a 28-day curing period, pozzolanic reactions improved significantly the three-axial peak strength and stiffness of the stabilized soil, and the maximum three-axial shear strength and stiffness occurred in the samples prepared below their OMC.

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Experimental analysis of steel fiber reinforced concrete beams in shear

Revista IBRACON de Estruturas e Materiais ◽

10.1590/s1983-41952022000300001 ◽

2022 ◽

Vol 15 (3) ◽

Author(s):

Aaron Kadima Lukanu Lwa Nzambi ◽

Dênio Ramam Carvalho de Oliveira ◽

Marcus Vinicius dos Santos Monteiro ◽

Luiz Felipe Albuquerque da Silva

Keyword(s):

Shear Strength ◽

Reinforced Concrete ◽

Steel Fiber ◽

Concrete Beams ◽

Reinforcement Ratio ◽

Steel Fibers ◽

Reinforced Concrete Beams ◽

Experimental Program ◽

Longitudinal Reinforcement ◽

Fiber Addition

Abstract Some normative recommendations are conservative in relation to the shear strength of reinforced concrete beams, not directly considering the longitudinal reinforcement rate. An experimental program containing 8 beams of (100 x 250) mm2 and a length of 1,200 mm was carried out. The concrete compression strength was 20 MPa with and without 1.00% of steel fiber addition, without stirrups and varying the longitudinal reinforcement ratio. Comparisons between experimental failure loads and main design codes estimates were assessed. The results showed that the increase of the longitudinal reinforcement ratio from 0.87% to 2.14% in beams without steel fiber led to an improvement of 59% in shear strength caused by the dowel effect, while the corresponding improvement was of only 22% in fibered concrete beams. A maximum gain of 109% in shear strength was observed with the addition of 1% of steel fibers comparing beams with the same longitudinal reinforcement ratio (1.2%). A significant amount of shear strength was provided by the inclusion of the steel fibers and allowed controlling the propagation of cracks by the effect of stress transfer bridges, transforming the brittle shear mechanism into a ductile flexural one. From this, it is clear the shear benefit of the steel fiber addition when associated to the longitudinal reinforcement and optimal values for this relationship would improve results.

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Multi-scale laboratory evaluation of the physical, mechanical, and microstructural properties of soft highway subgrade soil stabilized with calcium carbide residue

Canadian Geotechnical Journal ◽

10.1139/cgj-2015-0245 ◽

2016 ◽

Vol 53 (3) ◽

pp. 373-383 ◽

Cited By ~ 51

Author(s):

Ning-Jun Jiang ◽

Yan-Jun Du ◽

Song-Yu Liu ◽

Ming-Li Wei ◽

Suksun Horpibulsuk ◽

...

Keyword(s):

Particle Size ◽

Size Distribution ◽

Calcium Carbide ◽

Clayey Soils ◽

Microstructural Properties ◽

Curing Time ◽

Multi Scale ◽

Calcium Carbide Residue ◽

Mechanical And Microstructural Properties ◽

Highway Embankment

Calcium carbide residue (CCR) is an industrial by-product, stockpiles of which are rapidly accumulating worldwide. Highway embankment construction has been identified as an avenue to consume huge quantities of CCR as an economical, less energy intensive, and environmentally friendly chemical additive for soil stabilization. Previous studies have investigated the mechanical behavior of soils stabilized by CCR or blends of CCR with other additives; however, interpretation of the macroscale geomechanical behavior of CCR-stabilized soft soils from a systematically microstructural observation and analysis is relatively unknown. This paper presents a multi-scale laboratory investigation on the physical, mechanical, and microstructural properties of CCR-stabilized clayey soils with comparison to quicklime-stabilized soils. Several series of tests were conducted to examine the Atterberg limits, particle-size distribution, compaction characteristics, unconfined compressive strength, California Bearing Ratio, and resilient modulus of the CCR-stabilized clayey soils. The influences of binder content, curing time, and initial compaction state on the physical and mechanical properties of treated soils are interpreted with the aids of physicochemical and microstructural observations including soil pH, soil mineralogy obtained from X-ray diffraction and thermogravimetric analysis, and pore-size distribution obtained from mercury intrusion porosimetry. Soil particle flocculation and agglomeration at the early stage and pozzolanic reactions during the entire curing time, which originate from the finer particle size, greater specific surface area, and higher pH value of CCR, are the controlling mechanisms for the superior mechanical performance of CCR-stabilized soils. The outcomes of this research will contribute to the usage of CCR as a sustainable and alternative stabilizer to quicklime in highway embankment applications.

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