13.2
Ejemplo de diseño: juntas en pavimentos de hormigón
Las juntas de pavimento de hormigón son esenciales para mantener la integridad estructural y la longevidad del pavimento, ya que controlan dónde y cóm…
Se propone la ampliación de un pavimento de hormigón liso existente para su construcción mediante losas de hormigón, lo que garantiza un agrietamiento mínimo del pavimento.
Un ingeniero de pavimentos decide proporcionar juntas de construcción, expansión, aislamiento y contracción para controlar el agrietamiento del pavimento.
Las juntas de construcción son espacios dispuestos entre la nueva losa y una losa existente para permitir cualquier posible movimiento en la nueva losa. Las barras de espigas incrustadas en el hormigón unen las losas adyacentes.
Las juntas de dilatación son espacios provistos entre losas adyacentes para permitir la expansión térmica del hormigón.
Su construcción consiste en la disposición de las barras de espigas en filas en la dirección transversal del pavimento y el vertido de hormigón sobre las barras.
A continuación, el espacio que queda se rellena con rellenos y selladores compresibles.
Se proporcionan juntas de aislamiento donde el pavimento se encuentra con un pozo de inspección. Una junta de media pulgada de ancho alrededor del pozo de registro, llena de un material compresible, forma la junta de aislamiento.
Por último, la junta de contracción se proporciona mediante el aserrado de una ranura en el pavimento de hormigón recién endurecido orientada perpendicularmente a la dirección del flujo de tráfico.
Esto ayuda a localizar y controlar la formación de grietas durante la contracción del hormigón.
View the full transcript and gain access to JoVE Core videos
Q1: What are the main types of joints used in concrete pavement design?
Concrete pavements use four primary joint types: construction joints, which connect new and existing slabs; expansion joints, which accommodate thermal expansion; isolation joints, which separate pavement from fixed objects like manholes; and contraction joints, which are saw-cut grooves that control crack formation. Each joint type serves a specific function in managing pavement movement and preventing random cracking.
Q2: How do construction joints work in concrete pavement extensions?
Construction joints are gaps between new and existing concrete slabs that allow movement in the new slab during curing. Dowel bars embedded in the concrete tie adjacent slabs together, transferring loads while permitting controlled movement. This design prevents stress concentration at the interface between old and new pavement sections.
Q3: Why are expansion joints necessary in concrete pavements?
Expansion joints accommodate concrete's thermal expansion, preventing high compressive forces that can cause joint spalling or structural failure. These joints are created by arranging dowel bars in transverse rows and filling the gap with compressible fillers and sealants. This allows adjacent slabs to expand independently without damaging the pavement structure.
Q4: What is the purpose of contraction joints in concrete pavements?
Contraction joints are saw-cut grooves made perpendicular to traffic flow in recently hardened concrete. These joints create a weakened vertical plane that localizes and controls crack formation during concrete's contraction, directing cracks to predetermined locations rather than allowing random cracking across the slab.
Q5: How are isolation joints designed around pavement obstacles?
Isolation joints are provided where pavement encounters fixed objects like manholes. A half-inch wide joint filled with compressible material surrounds the obstacle, allowing the pavement and adjacent structures to move independently. This prevents stress transfer between the pavement and the fixed object.
Q6: What materials are used to fill concrete pavement joints?
Concrete pavement joints are filled with compressible fillers and sealants that accommodate movement while maintaining structural integrity. These materials allow adjacent concrete sections to expand and contract independently while preventing water infiltration and debris accumulation in the joint spaces, ensuring long-term pavement durability.
Q7: How do dowel bars function in concrete pavement joints?
Dowel bars are embedded in concrete to tie adjacent slabs together while facilitating controlled movement. In construction joints, they connect new and existing slabs; in expansion joints, they're arranged in transverse rows to transfer loads. This design maintains load transfer capacity while allowing thermal and contraction movements.