Product Overview

Centrament Retard is a set-retarding admixture from MC-Bauchemie based on a hydroxycarboxylic acid or lignosulphonate-gluconate blend that retards the hydration of Portland cement by adsorbing onto the surface of calcium silicate and calcium aluminate clinker particles, forming a thin inhibiting layer that slows the dissolution and hydration reaction rate. The retardation mechanism allows concrete to remain workable for a longer period after mixing — the concrete behaves as fresh, placeable concrete for the extended working period and then sets and gains strength normally after the retarding effect is exhausted. The fundamental need for Centrament Retard in Indian construction is the extreme hot weather concreting challenge in the North Indian plains: at ambient temperatures of 40 to 47 degrees Celsius in May and June in Delhi NCR, Ghaziabad, Agra, Kanpur, and the broader Indo-Gangetic plain, the concrete temperature at the point of mixing may reach 35 to 40 degrees Celsius (already at the IS 456 hot weather concreting precaution threshold of 35 degrees Celsius for concrete temperature at point of delivery) — at this concrete temperature, the initial set time for OPC concrete without a retarder may be as short as 30 to 40 minutes, creating critical risks of: construction joints forming within raft slab pours where concrete is placed in one area before an adjacent area can be poured; slump loss during truck transport from RMC plant to site in heavy Delhi NCR traffic (30 to 60 minute haul times are common); flash set of concrete in pump lines during brief stoppages caused by congestion at the point of placement; and inadequate time for surface finishing operations on flat slab and pavement pours before the concrete stiffens. Centrament Retard addresses all these risks by providing a controlled, predictable extension of the initial set time — fully compatible with the Centrament Flow PCE superplasticiser range for combined water reduction and workability retention. Space Arc Engineering supplies Centrament Retard for RMC plants, site batching plants, and concrete contractors in Ghaziabad, Delhi NCR, Noida, and Uttar Pradesh for summer concreting operations.

Applications

• Hot weather raft slab concreting in summer — retardation of large raft slab pours in residential and commercial buildings in Ghaziabad and Delhi NCR during April to June when ambient temperatures reach 40 to 47 degrees Celsius — raft slabs of 1,000 to 5,000 cubic metres poured in a single continuous operation require workable concrete at the pour face for 2 to 4 hours after mixing to prevent cold joints forming where fresh concrete is placed against partially set concrete — Centrament Retard at 0.2 to 0.4 percent by mass of cement extends the initial set time by 2 to 3 hours, providing the workability window required for large continuous raft pour operations in Indian summer conditions
• Ready-mix concrete long-haul delivery in heavy urban traffic — extending the workable life of ready-mix concrete delivered from RMC plants in Ghaziabad, Noida, and Faridabad to construction sites in central Delhi, where urban traffic congestion routinely extends truck haul times to 60 to 90 minutes — without Centrament Retard, the concrete arriving at a central Delhi construction site in May at 40 degrees Celsius ambient may have less than 15 minutes of remaining workability, making it unusable for structural concrete placement; with Centrament Retard at the appropriate dosage, the concrete maintains workability throughout the haul plus placement time
• Mass concrete abutments, pier caps, and thick sections — retardation of mass concrete pours in bridge abutments, pier caps, thick raft slabs, and retaining walls where the large concrete volume generates significant heat of hydration, causing the internal concrete temperature to rise 20 to 30 degrees Celsius above the ambient temperature — this temperature rise further accelerates cement hydration and shortens the working time; Centrament Retard provides extended workability and delays the peak temperature rise, reducing the differential temperature between core and surface and lowering the risk of early thermal cracking in mass concrete sections
• Slip-form and continuously poured concrete operations — retardation of concrete in slip-form construction of silos, chimneys, cooling towers, and bridge piers where the continuous concrete operation requires consistent concrete plasticity at the point of form lifting — the concrete must remain plastic long enough to be placed and consolidated below the slipping form but must set and gain adequate strength to support the form and the weight of the fresh concrete above within the slip cycle time — Centrament Retard provides the precisely controlled retardation required for slip-form operations
• Precast concrete summer production — retardation of precast concrete mixes in precast manufacturing plants in Delhi NCR where the combination of high ambient temperature, direct sun on the precast beds, and exothermic release of heat from the cement hydration causes the concrete to set too rapidly for adequate consolidation and surface finishing before the precast bed is closed — Centrament Retard extends the working time while still allowing the precast element to achieve demoulding strength within the planned production cycle time of 18 to 24 hours (the retarding effect is exhausted before the demoulding time, and the concrete achieves its normal strength gain thereafter)

Key Advantages

• Controlled, predictable workability extension — the retardation time is proportional to the Centrament Retard dosage, allowing the concrete designer and RMC plant technologist to specify exactly the required workability extension (1 hour, 2 hours, or 3 hours) by adjusting the dosage — the predictable retardation-dosage relationship (established by trial mixes with the specific cement and aggregates to be used) avoids the variability of site-added water or uncontrolled cement substitution as workability management strategies
• No long-term strength reduction — Centrament Retard delays the onset of hydration but does not reduce the ultimate quantity of hydration products or the 28-day and 56-day compressive strength — the 28-day strength of retarded concrete is equal to or slightly higher than non-retarded control concrete of the same w/c ratio — any minor 1-day or 3-day strength reduction is irrelevant for structural concrete design based on 28-day strength
• Compatible with PCE superplasticisers — Centrament Retard is compatible with the Centrament Flow PCE superplasticiser range — the two admixtures can be combined in a single mix design for combined water reduction (PCE) and workability retention (retarder) — this combination is the standard specification for high-performance hot weather concrete in India: low w/c for durability, PCE for workability at low w/c, and Centrament Retard for workability retention during the delivery and placement period
• Reduces risk of cold joints in large pours — the extended workability window eliminates the practical time limit on concrete pour size in hot weather — with Centrament Retard, a 2,000 cubic metre raft slab pour can be planned and executed as a single continuous operation rather than being broken into sequential sections with planned cold joints — reducing the number of construction joints, the waterproofing joints requiring detailed treatment, and the overall pour planning complexity
• IS 9103 compliant — Centrament Retard complies with IS 9103 (Specification for Admixtures for Concrete) requirements for Type B (set-retarding) or Type D (water-reducing and retarding) admixtures — providing specification compliance for projects governed by IS codes as required by Indian government infrastructure contracts