Importance of long life waterproof concrete; achieves sound buildings and structures
Our director Mr Robert Speirs-Ferrari who is a diagnostic construction and waterproofing expert, offers the following observations from his many years (40+ years) education and experience with waterproofing and construction failures.
According to the National Construction Code – Building Code of Australia (NCC/BCA), buildings, structures and civil concrete infrastructure, and all types of residential and commercial buildings including strata properties, must be provided with long-life waterproofing protection. Construction is required to last 50 to 60 years with only minor maintenance. Due to the history of faulty construction, lack of supervision and the use of incorrect products, buildings and structures fail well short of the Building Code of Australia and the applicable Australia Standards. Strata residential buildings suffer the most damage and disruptive to the owners and tenants of these buildings. All at tremendous costs and destruction of peoples lives, environments and creating financial difficulties.
He advises Building Diagnosis Centre have continuously for 40 + years built / project managed and investigated new and defective construction, in his capacity as building diagnostician, project manager and as an expert witness. Drafted specifications for new building contracts and remedial works contracts for clients with deteriorating buildings and structures. Especially water ingress through the building fabric. He advise the most common and expensive remedial works relate to rectifying incorrect, failed and deteriorated liquid waterproofing. Including certain sheet membranes all contributing to concrete cracking. and premature concrete deterioration (i.e. spalling concrete) and unnecessary inconvenience and expense on the owners of these buildings.
As a consulting waterproofing and construction expert, he advise it is common knowledge in the building and construction industry including with property owners and strata managers, that over the last 20 years, waterproofing failures of concrete has become the most major and expensive common construction rectification issue. With exception to differential settlement movement of structures requiring buildings to be partly demolished or to be vacated to allow for extensive expensive remedial work.
Concrete construction types and structural issues and damage:
Construction components especially exposed external façades, rooftops, concrete basements, retaining walls, and concrete components of infrastructure like roadway over-passes, bridges, wharves, and the like, all have one thing in common. They can allow water to ingress concrete when not properly waterproofed.
Structural concrete issues occur from premature deterioration either due to not being satisfactory constructed and waterproofed at the construction stages. Also from failed waterproof coatings, sheet membranes and incorrect concrete placement causing shrinkage cracks to develop. Robert advise damaged concrete is caused from being porous due to low cement content, moisture migration and atmospheric pollutants including coastal soluble salt ingress even into ‘sound looking’ concrete.
He advises the damaged structural concrete components without sound waterproofing, eventually suffer with structural concrete explosion from the embedded unprotected reinforcement steel. Due to the reinforcement suffering rust corrosion expansion.
The term widely used for damage concrete is “spalling concrete cancer”. The premature structural concrete damage from concealed rust corrosion of the steel reinforcement, he advises can occur within 15% to 20% of the 60 to 100 year life expediency of concrete. Thus requiring extensive and expensive early structural remedial work that often owners and investors have not allowed for in their budgets.
Waterproofing and National Construction Code Building Code of Australia
Traditional waterproofing products are liquid waterproofing and sheet waterproofing membrane systems installed onto concrete surfaces at each post-construction stage. Liquid waterproofing membranes usually have 6-years installation workmanship warranty period and can perform for 10-years under the manufacturer warranty period. Sheet waterproofing membranes can have up to 20-years warranty provided the sheet membrane is not damaged by the occupants or from other issues including building movement and during the construction. Warranty periods are quite short when considering the life expectancy of buildings and structures is 60 years according to NCC/BCA. However buildings do last 100 + years but normally require expensive maintenance / rectifications. Robert advises in the last 30 years a new breed of building contractors have developed and are referred to as “Remedial Builders”.
Concrete quality and strength is not always consistent
It’s common knowledge soundly constructed concrete with high strength 40 MPa concrete mix (not the lower strength concrete 20 – 30 MPa) without cracks is or almost waterproofed. Concrete protected with best applied surface waterproofing systems normally don’t fail if professionally installed, the correct products are applied including allowing for movements in buildings and structures.
However many concrete failures (i.e. cracking causing spalling concrete cancer) occur when the concrete is not properly cured at the construction stage which unfortunately is often the case. Cracking occurs making the concrete not waterproof. Rainwater and contamination (salts and the acid environment) penetrate cracks causing the embedded reinforcement steel to corrode. This causes concrete expansion hence wider cracking allowing more water and contaminants to penetrate deeper thus further concrete damage occurs and often goes undetected. Damage is only detected once the concrete surface cracks, and displaced from the building to the ground or sections of concrete sag and deflect or worst case scenario collapse.
Waterproof concrete free of damage can be achieved with long life embedded ‘Hydrogel’ waterproofing chemicals
To avoid concrete damage and achieve long life concrete. Robert Speirs-Ferrari believes is to initially have a Hydrogel (an environmental friendly safe water-based waterproofing liquid chemicals) mixed within 40 MPa concrete to control shrinkage cracking. This long-term waterproofing liquid penetrating chemical, chemically cure the concrete after it is poured in-situ. Long life waterproofing chemicals is an alternative waterproofing system and methodology to the usual surface applied waterproofing membranes and sheet membranes. He advises the following from experience in the Building and Construction Industry and as expert witness in building claims and 1000’s of failed waterproofing events he has investigated.
- Hydrogel water-based waterproofing liquid chemicals is successfully used throughout Australia and New Zealand and other overseas markets for large buildings and structures include public infrastructure, coastal properties, wharfs, basements and below ground constructions. User safe and environmental friendly, Hydrogel waterproofs inside the concrete extending out to the surface to stop water migration at the forefront.
- Concrete treated with Hydrogel waterproofing liquid chemicals prevent moisture born contaminants including coastal soluble salt chloride environments from entering concrete structures usually via porous concrete (faulty) and concrete shrinkage and movement cracking. These moisture born soluble contaminants also penetrate through surface applied liquid waterproofing membranes and sheet membrane at locations of deterioration and damaged sheet joints. Exposed concrete floor beams, columns and slab edges protected with Hydrogel waterproofing stops moisture born contaminants from migrating for life. Independent chemical testing laboratories show Hydrogel helps to arrest deterioration reactions, thus restore, and extend beyond the design service life of buildings and structures. Robert advises this waterproofing liquid chemical therefore stop cracking and concrete damage and corrosion of the embedded reinforcement steel for the life of the concrete.
- Soundly constructed reinforced concrete buildings, structures, roofs and balcony floor slabs without these corrosive penetrating contaminants, will prevent concrete damage. Including to connecting building components. Concrete without these Hydrogel water-based waterproofing liquid chemicals will suffered premature damage and deterioration eventually causing embedded reinforcement steel expansion from rust corrosion. He advise it financially benefits building contractors, building owners including governments and the end users of buildings and structures including private investors and saves our government building costs.
- The the common in usual surface applied liquid waterproofing and sheet waterproofing systems are no longer required, when Hydrogel water-based waterproofing liquid chemicals are within the concrete. As the hydrogel water-based waterproofing liquid chemicals prevent moisture born contaminants entering and migrating through the concrete resulting in contaminating the reinforcement steel hence expansion cracking. Hydrogel waterproofing chemicals help arrest deterioration reactions, and restore, and extend beyond the design service life of concrete building elements and structures. Robert advises that the usual liquid and sheet waterproofing membrane systems are no longer required. Therefore the Hydrogel chemicals save other concealed parts of buildings from damage; normally need to be replaced when damage liquid and sheet membrane waterproofing is being replaced.
- Robert also advises that his Building Diagnosis Centre project managers and inspectors specify and oversee structures when being waterproofed with these waterproofing liquid chemicals. The on-site product process is sprayed over the fresh concrete, where it then penetrates a minimum of 150 mm into the concrete structure. Thus controlling shrinkage cracking therefore locking out salt water contaminated and acid environment from entering once sufficiently dry and or to walk upon. The Hydrogel waterproofing chemicals cure the concrete surface after penetrating the minimum 150mm into the concrete structure thus controls shrinkage cracking therefore locking out water and contaminated salts and acid environment from entering.
- Robert advises architects, engineers, building designers, builders, contractors, property owners and managers, when concrete in buildings and structures are treated with Hydrogel waterproofing chemical systems, they meet the Performance Solution requirements of the National Construction Code Building Code of Australia (NCC/BCA) and therefore meets requirements of the local government councils and private certifiers.