WHAT IS PUDLO?
PUDLO CWP is a hydrophobic and pore-blocking admixture. A dual-purpose, multi-component, cementitious powdered admixture providing outstanding durability and waterproofing properties to all concrete mixes. It also enhances plasticising and corrosion-inhibiting benefits. PUDLO CWP conforms to BS EN 934-2 as water resisting admixture.
PUDLO outperforms any other admixture of its kind in both durability and impermeability. Where long term durability is critical and / or exposure to aggressive environments is present, PUDLO provides significant and cost effective solutions when added to the concrete mix.
Hydrophobic: The hydrophobic element of PUDLO provides hydrophobic lining along the pore walls reducing the surface tension, capillary suction and absorption properties of concrete.
Pore blocking: In addition to providing hydrophobic lining, PUDLO also produces pore-blocking compounds. These compounds permanently seal remaining voids in the concrete to further increase structural durability, providing an additional level of protection against water migration and corrosive attack.
Durability is the ability of concrete to resist weathering action, chemical attack, and abrasion while maintaining its desired engineering properties. Different concretes require different degrees of durability depending on the exposure environment and the properties desired. Concrete ingredients, the proportioning, performance, placing and curing practices, and the service environment determine the ultimate durability and life of the concrete.
The use of PUDLO CWP causes the reduction of the ingress of water within concrete through flow under pressure as well as absorption.
The impermeability (waterproofing) is the single most important performance characteristic with respect to preventing the ingress of the aggressive substances within the concrete, and thus the biggest influence on long term durability. The benefits of using PUDLO CWP modified concrete thereof are discussed in more detail below.
Permeability is a flow property of concrete which quantitatively characterizes the ease by which a fluid will pass through it, under a pressure differential.
Capillary pore size and pore interconnections are important factors affecting permeability of concrete. PUDLO modified durable concrete exhibits reduced capillary pore size and increase the tortuosity of pore networks by densifying the microstructure and physically blocking the pores to reduce the movement of moisture due to hydrostatic pressure.
The reduction in permeability and the associated decrease in the rate of the ingress of the aggressive substances within concrete is one of the most important attributes in relation to enhancement of the durability of concrete (Hewlett, 1998).
Absorption is a process by which concrete takes in water by capillary action. Factors affecting absorption are moisture gradient, capillary pore size and pore interconnection.
The hydrophobic properties of PUDLO significantly reduce the capillary suction. Thus concrete treated by PUDLO has very low water absorption values.
Diffusion & Chloride Induced Corrosion
Diffusion and Chloride Induced Corrosion is a process by which water, vapour gas or ions can pass through concrete under the action of a concentration gradient. This, in the case of for example chloride ions can cause corrosion of the reinforcing steel.
PUDLO modified durable concrete effectively protects the steel reinforcement from corrosion induced by both chloride ingression and carbonation process by reducing the diffusion rate of the aggressive substances by modifying the pore structure of the hardened concrete.
Sulphate attack is characterized by the chemical reaction between sulphate ions from the ground water with aluminate and calcium component of hardened Portland cement. The reaction leads to the formation of expansive gypsum and etringite. This causes expansion leading to cracking, allows further ingress of sulphate and accelerates the degradation process.
By enhancing the permeation properties, PUDLO makes concrete water resistant, therefore PUDLO treated concrete is more resistant to sulphate attack.
PUDLO to Resist Corrosion
The unique properties of PUDLO densify the cement paste by reducing the porosity and pore sizes. This enhanced microstructure reduces the permeability and diffusion properties of PUDLO modified concrete making into a high performance and durable concrete. It also significantly reduces the absorption of concrete by providing hydrophobic lining along the pore walls, thus reducing capillary suction of pores.
By enhancing the permeation properties such as reducing the permeability, absorption and diffusion into concrete, PUDLO CWP makes the concrete considerably more water resistant with a fivefold reduction in permeability relative to the control concrete. Such attributes are key factors for minimising steel corrosion, providing greater chloride and sulphate resistance and thus a more durable concrete.