An expansion joint or movement joint is an assembly designed to safely absorb the heat-induced expansion and contraction of construction materials, to absorb vibration, to hold parts together, or to allow movement due to ground settlement or earthquakes. They are commonly found between sections of buildings, bridges, sidewalks, railway tracks, piping systems, ships, and other structures.
Building faces, concrete slabs, and pipelines expand and contract due to warming and cooling from seasonal variation, or due to other heat sources. Before expansion joint gaps were built into these structures, they would crack under the stress induced.
Bride expansion joints are designed to allow for continuous traffic between structures while accommodating movement, shrinkage, and temperature variations on reinforced and prestressed concrete, composite, and steel structures. They stop the bridge from bending out of place in extreme conditions, and also allow enough vertical movement to permit bearing replacement without the need to dismantle the bridge expansion joint.
There are various types, which can accommodate movement from 30 to 500 millimetres. They include joints for small movement and medium movement and large movement.
Modular expansion joints are used when the movements of a bridge exceed the capacity of a single gap joint or a finger type joint. Modular multiple-gap expansion joints can accommodate movements in every direction and rotations about every axis. They can be used for longitudinal movements of little as 160 mm, or for very large movements of well over 3000mm. The total movement of the bridge deck is divided among a number of individual gaps which are created by horizontal surface beams. The individual gaps are sealed by watertight elastomeric profiles, and surface beam movements are regulated by an elastic control system. The drainage of the joint is via the drainage system of the bridge deck. Certain joints feature so-called “sinus plates” on their surface, which reduce noise from over-passing traffic by up to 80%.
KRIDHAN-C type, KRIDHAN-Z type, KRIDHAN-F type, KRIDHAN-L type bridge expansion device are suitable to bridge joints with expansion amount less than 80mm.
Features & Benefits
The KRIDHAN type RE and RE-LS single gap joint systems are expansion joints for gap widths up to 80 mm for the RE type and 100 mm for the RE-LS type (these values can vary depending on the construction standard).
Type RE-LS is also equipped with a nisereducing surface in the form of “sinus plates”. This results in noise reduction of up to 80%. The steel edge profiles of the KRIDHAN expansion joints are anchored in KRIDHAN waterproof polymer concrete. The joints are suitable for new constructions as well as for refurbishment projects. A major advantage is the fast and cost-effective installation of the system, because the joint is only installed in the cross-sectional area of the wearing surface and no further interference with the underlying carrying construction takes place.
The KRIDHAN expansion joint is mainly used for asphalt and concrete connections and can be installed on virtually all new and existing bridges. Thanks to its low installation depth, it is particularly suitable for retrofitting in cases where bituminous expansion joints are rolled out or are fissured as a result of intensive use. The same applies to the replacement of worn mat joints (e.g. those damaged by heavy vehicles and equipment). Fast installation time of KRIDHAAN expansion joints and the additional possibility of phased assembly reduce traffic congestion.
Anchoring no additional reinforcement or anchoring is necessary with the KRIDHAN expansion joints. All loads are transmitted directly through the bond between the polymer concrete and the substructure. To allow the transmission of forces into the adjacent structural elements, the surface of the recess must have a minimum tensile bond strength of 1.5 N/mm2 (concrete) or 3.0 N/mm2 (steel). KRIDHAN should not be applied to new concrete within 14 days of pouring.
The installation of the KRIDHAN expansion joints and the insertion of the KRIDHAN polymer concrete must be carried out by qualified and certified personnel. The on-site coordination of these activities is carried out by our experienced project managers or trained personel by KRIDHAN.
1. Exposed recess.
2. Positioned RE-LS type expansion joint.
3. Mixing of the polymer concrete.
4. Laying of the polymer concrete.
Compressive strength (Prism 40x40x160 mm, 28d) at least 22.3 N/mm2
Tensile strength (Prism 40x40x160 mm, 28d) at least 7.4 N/mm2
E modulus (Prism 40x40x160 mm, 28d) at least 55 N/mm2
Bond to sand-blasted steel at least 3.0 N/mm2
Bond to sand-blasted concrete at least 1.5 N/mm2
The following high-quality materials are used for the production of the KRIDHAN expansion joints:
The application surface temperature and air temperature for the installation of the KRIDHAN polymer concrete must be between 8 C and 30 C. Depending on the temperature, the polymer concrete is sufficiently hard within 4 to 6 hours curing time to withstand the traffic loads.
After uncovering the recess – by removing the previously laid asphalt layer the old joint – the further steps for the installation of KRIDHAN expansion joint are as follows:
1. Surface preparation pre-treatment (e.g. sand blasting) of concrete or steel surface in the recess, so that it reaches the tensile bond strength of 1.5 n/mm2 (concrete) or 3.0 n/mm2 (steel).
2. Setting up the profiles Lining and levelling of the edge profiles.
3. Laying the polymer concrete the polymer concrete is mixed, poured and cured to form a smooth carriageway surface. Due to its excellent distribution properties no cavities are left and no additional compaction is necessary. The polymer concrete reaches the compressive strength required to withstand the traffic loads within 4 to 6 hours (depending on temperature).
4. Sealing profile: Insertion of the KRIDHAN sealing profile over the entire length of the joint if the latter has been installed in stages (e.g. laneby-lane). Otherwise, the sealing profile is already installed in the factory.
Quality & Support
For five decades, KRIDHAN expansion joints have proven their worth in thousands of structures under the most demanding conditions. In addition to the product properties, the extensive experience of our well-qualified manufacturing and installation staff also contributes to the high quality and durability of the products. KRIDHAN has a process-oriented quality system that is certified in accordance with ISO 9001:2008. Quality is also regularly inspected by independent institutes.
Saving on steel.
Faster connection cycle.
Modern construction techniques.
Demand for increased speed in construction
Increased labour and material costs.
Safety performance criteria for excellent connection strength.
Add. Value to construction.
Traditionally accepted from of splicing reinforcing steel bars has been to lap them. The method involves placing two bars together next to each other, over defined minimum lengths and then holding them in position using wire ties. At Kridhan infra ltd,. We have developed an innovative mechanical splicing system. The system involves the use of Couplers that is cost effective, quick effective, quick & easy to install in a superior office. Importantly engineers globally have recognized the advantage of the Kridhan system overlap splicing.
Designed and manufactured in compliance with AC1318, JGJ 107, UBC 1997, NF32-20-1, DIN 1045, ACI349.
Full-Tension splice, bar break under tensile tests.
Easy to operate and maintain, high production efficiency and fast installation, no need for skilled technicians. Several types of splices, which would be suitable for rebar slicing when the rebar cage or the blending –rebar is used.
The splices could be produced in advanced without influencing the construction period.
Inexpensive to purchase, maintain and repair.
Couplers and threaded bars are protected by plastic cover.
Full traceability of material origin and production batch.
Manufactured under strict quality assurance plan ISO 9001.
No staggering bars are required.
Practical alternative to lap splicing.
Solves bar congestion problems.
Shortens construction cycle time.
Reduces steel wastages.
Cutting: The end of rebar is cut square by special cutting machine for bar splicing or cutting machine with blade.
Upsetting: Enlarge the end of rebar by cold upsetting dies.
Threading: Cutting parallel thread on the enlarged end of rebar by roating chasers.
Splicing: Connection rebar by coupler.
Sys A- Normal Coupler: Parallel thread rebar spice with upset end. Both end short thread.
Sys B- Position Coupler: Parallel thread rebar spice with upset end. One end long thread and other end short thread.