Repair and rehabilitation of concrete pavements Indireddy
This paper provides an overview of the current methods of analysing and repairing cracks in concrete pavements. The Finite element method (FEM) models and non-destructive analysis method, and the repairing methods using electro-deposition, electro chemical, recycled steel fibres are reviewed.
Biogenic treatment improves the durability and remediates the cracks of concrete structures
Abstract Microbially induced calcium carbonate precipitation is a naturally occurring biological process that has various applications in remediation and restoration of range of building materials. In the present study the role of bacteria Bacillus sp. on the durability properties and remediation of cracks in cementitious structures were studied. “Biocement” induced by a Bacillus sp. lead to more than 50% reduction in the porosity of mortar specimens, while chloride permeability of concrete changed from “moderate” to “very low” as indicated by rapid chloride permeability test. The bacteria successfully healed the simulated cracks of depths including 27.2 mm in cement mortars with increase in the compressive strength as high as 40% of that of control. The results clearly showed microbially induced calcium carbonate precipitation can be applied for various building materials for remediation of cracks and enhancement of durability.
Mechanical behaviour and durability of high volume fly ash cementitious composites
The purpose of this research is to separate different morphological particles of ASTM class F fly ash, and study their effect on mechanical behaviour and durability of high volume cementitious mixtures. In this research wet separation of raw fly ash is carried out, which resulted in three layers of different morphological particles. The first layer of particles float, comprise of about 1-5% of fly ash, is identified as cenospheres or hollow spheres. The second layer of particles is measured to be 55-60% of raw fly ash and consisting of porous spherical and rounded particles rich in Si and Al. The third layer particles is measured to be about 35-40% of raw fly ash. High volume fly ash cementitious composites containing second or third layer particles are tested under compression and bending, highlighting a higher strength and ductility in comparison to cementitious ones containing raw fly ash particles. KEYWORDS. Cementitious matrix; Raw fly ash; Second layer particles; Third layer particles.