An improved post-initial set applied colloidal silica – a liquid densifier that strengthens concrete from within – distributed by concrete protection supplier SprayLock Africa is strengthening the floors of numerous mining, industrial and commercial sites.

The Spray-Lock Concrete Protection (SCP) Post-Placement Pozzolan (P3) silica “actively interacts with the concrete matrix, as it is designed to permanently waterproof and protect new or existing concrete by sealing capillary voids, reducing moisture migration and improving durability,” says SprayLock Africa MD Carl White.

With SprayLock filling the concrete capillaries, water, oxygen and sulphates cannot penetrate, thereby protecting and extending the life of the concrete.

The SCP P3 particles react with the alkalis that occur naturally in the pore space of concrete, specifically calcium hydroxide. This reaction produces additional calcium silicate hydrate (C-S-H) in an amorphous form that is indistinguishable from the C-S-H produced from cement hydration.

However, it differs from the crystalline C-S-H that is formed from most surface- applied densifiers, as those crystalline formations are not a permanent reaction product and are subject to fatigue after repeated wetting and drying cycles, explains White.

“When we say, ‘deep penetration’ we do not mean the 5 mm to 10 mm that many conventional topical sealers or densifiers reach,” he stresses, adding that SCP P3 products penetrate as deeply as the capillary void structure allows, often reaching the centre of a standard concrete slab. This significantly reduces maintenance cycles and ensures that the structure’s service life is extended.

“We have proven SCP P3’s efficiencies at a prominent fast-moving consumable goods silo complex, at various coal silos, on a large bridge repair project, as well as at a group of data centres,” he points out, citing the diverse range of applications in which the silica product can be used.

Research Interest

The success of SCP P3 has garnered the attention of tertiary institution Stellenbosch University’s award-winning concrete researcher Talita Thesnaar.

Her work involves testing liquid densifiers, finishing techniques, dry-shake hardeners and experimental graphene-enhanced mixtures that provide distinct insights into concrete performance and durability. Among the products included in her investigation is SCP P3.

Thesnaar is evaluating abrasion, chloride penetration, stain resistance and durability.

“As the research continues, my objective remains consistent: To develop a deeper understanding of how these treatments influence the performance and life span of concrete floors.”

In terms of in-house testing, SprayLock has engaged with civil engineering company Specialised Concrete Consulting Services, which has assisted in durability testing, while the University of Cape Town’s Concrete Materials and Structural Integrity Research Unit conducted durability index testing.

The South African concrete market relies on additional durability index tests that include an oxygen permeability index, the chloride conductivity index, water sorptivity and carbonation.

White concludes that the SCP P3 silica is applied by approved specialist applicators using an airless spray machine.