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    Posts in Joint Sealing

    Maintenance of Concrete Expansion Joints

    June 23rd, 2017 Posted by Insights, Joint Sealing, Projects 0 thoughts on “Maintenance of Concrete Expansion Joints”

    FCS Concrete Repairs are fully resourced to provide maintenance and repair services for concrete Expansion Joints in commercial, industrial and residential properties.

    Expansion Joints in carparks and hardstand areas can also be repaired through permeation grouting of the sub-base to fill voids and polyurethane injection to lift the slab back to level where there is a step in the joint due to subsidence or washout. This process can avoid extremely costly and disruptive demolition and replacement of the concrete slab.

    FCS Concrete Repairs are experts in the field of concrete repair and are approved contractors for the major suppliers of joint sealants and joint repair products.

    You can rely on FCS Concrete Repairs, as we are Quality Accredited under the International Standard ISO 9001: 2015 to carryout quality workmanship with full backup services, if required.

    Expansion Joint Re-sealing

    Expansion Joints in concrete floors and walls control movement and over time the joint sealant can deteriorate. The sealant can be removed and replaced to ensure that the joint is waterproof and performs as required.

    Expansion Joint Reinstatement

    Expansion joints require that the facing edges of the adjoining concrete slabs are sound so that the flexible joint sealant forms a strong bond between the concrete slab or wall elements. Industrial floors, which may be on ground or suspended, require regular maintenance as they are vulnerable to impact damage from mobile plant including forklifts which are often hard-wheeled. Broken and crumbling edges along an expansion joints is an indication of future extensive and costly damage.

    Where considerable damage has occurred it may be necessary to carry out more extensive repair including concrete saw cutting and edge reinstatement. Regular inspection is a cost saving option to ensure that the jointing material is still performing and protecting the concrete joint edge faces. Heavy duty repair mortars may be required to re-construct the joint and these can be fast drying/curing to minimise downtime. FCS Concrete Repairs can provide professional advice in this regard.

    Widening Expansion Joints

    Expansion Joints may widen over time due to slab movement and damage.

    Narrow expansion joints can provide a smoother transition across the joint and minimise future damage. FCS Concrete Repairs can re-form wide expansion joints cost effectively to reduce the gap and the impact over widening joints.

    Joints are not the problem; Cracks are!

    June 23rd, 2017 Posted by Blog, Concrete Repair, Concrete Repairs, Joint Sealing, Reinforced Concrete 0 thoughts on “Joints are not the problem; Cracks are!”

    Joints are placed in concrete pavement to accommodate slab movement and to prevent natural cracking. The theory is that cracking will follow along the joints if they are correctly positioned.

    The first concrete pavement slabs had no real design and no crack control joints or dowels and no steel reinforcement.

    In the first part of the 1900s Joint Reinforced Concrete Pavement appeared containing steel reinforcement mesh to hold cracking tightly. Then followed Jointed Plain Concrete Pavement using contraction joints to control cracking with no reinforcement steel and dowel bars were introduced to transverse joints to assist in load transfer in 1917. In 1923 Continuous Reinforced Concrete Pavement was introduced whereby transverse cracks are allowed to form but are held tightly together with continuous reinforcing steel.

    Joint Spacing

    Joint spacing is very important in crack control as cracks can form naturally during the curing process without suitable control joints in place.

    The formula for maximum joint spacing is the relationship between:

    • The radius of relative stiffness (mm),
    • the modulus of elasticity of concrete (Mpa)
    • the slab thickness (mm),
    • the modulus of subgrade reaction (Mpa/m),
    • Poisson’s ratio for concrete, usually 0.15.

    Saw Cutting

    There is a short window of opportunity for saw-cutting joints in slabs. Too early and you get ravelling of the joint and the faces are torn and damaged. Too late and the internal stresses causing cracking have already started randomly in the slab.

    The saw cut depth and timing is critical for joint formation.

    Types of Joints

    There are several types of joints which can be transverse or longitudinal in direction:

    • Contraction Joints
    • Construction Joints
    • Isolation Joints
    • Expansion Joints

    All are designed to induce or control cracking.

    Joint Sealants

    Joint Sealants are used to minimise infiltration of surface water and incompressible material into the joint. Unsealed joints can allow sub-soil washout and voids to form and uneven subsidence of slabs resulting in differing RLs and rough transitions across joints.

    Dowel Bars

    Dowel Bars are used to control the joints and their alignment and spacing is critical. If dowels are misaligned and both ends of the dowels are locked in the slab concrete failure and cracking will result. The absence of dowels may cause the transitions across joints to become uneven when the adjoining slab moves out of level or concrete curling occurs.

    Dowel racks are an excellent innovation as they ensure that the dowels are aligned correctly and held in place during the concrete pour.

    Sub-base

    The sub-base material must be compactible and pumping of water through the sub-base through un-doweled joints needs to be eliminated.

    Curing

    Proper curing practices delay the development of these internal stresses, controls internal temperature, delays moisture evaporation, and fosters the development of increased strength.

    Curing therefore controls the evaporation of moisture during the concrete setting process and helps to prevent premature drying of the surface which can prevent or delay the evaporation of the remaining moisture below resulting in an uneven set and issues with strength and surface dusting.

    Steel Reinforcement

    The correct placement of steel reinforcement bars and mesh is critical to provide strength, reduce width and frequency of cracking and hold slabs together whilst setting and under load.

    Typical Jointing Problems

    • Concrete sawing too early causing ravelling or spalling
    • Concrete sawing too late causing early-age cracking
    • Concrete cracking due to insufficient joint depth
    • Concrete cracking due to excessive joint spacing
    • Concrete cracking due to excessive unrestrained warping
    • Concrete cracking due to too much edge restraint
    • Concrete cracking due to excessive slab to sub-base bonding
    • Concrete cracking due to misalignment of dowel bars
    • Concrete cracking due to lack of consideration of weather conditions
    • Sealant not adhering to joint faces
    • Sealant pulls out during operation
    • Sealant gelling
    • Sealant cracking or debonding
    • Voids of bubbles in sealant
    • Water pumping into sub-base
    • Sub-base washout
    • Concrete slab moving out of level

    The Solution

    FCS Concrete Repairs are fully resourced to Inspect, Test, Diagnose and make informed recommendations on the best permanent and cost effective methods to rectify any concrete cracking and maintenance issues. Joint repair and reinstatement is our forte!

    Ref: All About Concrete Pavement Joint Design & Construction
    September 19, 2013, Eric Ferrebee, EITTechnical Services Engineer, ACPA

    Expansion Joint Remediation – Wyong NSW

    June 23rd, 2017 Posted by Joint Sealing, Projects 0 thoughts on “Expansion Joint Remediation – Wyong NSW”

    Product Used:

    Sikaflex® Tank N is a 1-part Elastic Sealant for Joints Exposed to Chemicals.

    Sikaflex® Tank N is used in areas for the storage, filling and handling of water polluting liquids such as floor joints in petrol stations, joints in handling areas, storage tanks and containment bunds, movement- and connection joints according to IVD data sheet no. 1. I. E. in workshops and parking garages

    BEFORE

    AFTER

    Remediation Process:

    Prior to Sealing:

    • Removal of existing joints
    • Clean out existing expansion joints to depth of min 50mm using road saw with flat wire wheel
    • Clean out joints. Vacuum and sweep joints
    • Repair cracked concrete by pinning and stitching

    Sealing to Expansion Joints:

    • Tape up sides of joint repair with Masking Tape to avoid spilling over
    • Install foam backing rods into the joints
    • Prime seal expansion joints with Sika® Primer-3-N
    • Installation of Sikaflex® Tank N into joint at a min. depth of 15mm
    • Remove masking tape
    • Final Inspection and hand-over.
    Swimming Pool

    Hastings Pde North Bondi

    March 14th, 2017 Posted by Concrete Repair, Concrete Topping, Joint Sealing, Leak Sealing, Projects, Protective Coating, Swimming Pool 0 thoughts on “Hastings Pde North Bondi”

    Client: MDF Group
    Project: Hastings Pde North Bondi
    Location: North Bondi NSW
    Scope: Grind and apply SikaDur and Combiflex

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