Cement Types – Slower early strength but comparable long-term strength to OPC Which cement type generally develops a somewhat lower early-age strength than ordinary Portland cement during the first few months but later attains similar strength levels?

Introduction / Context:
Blended cements modify hydration kinetics and microstructure. While some types boost early strength, others trade early gain for improved durability and comparable or better later-age performance. Recognising these trends is important when scheduling formwork removal or specifying mixes for mass concrete and aggressive environments.

Given Data / Assumptions:

• Comparison is with ordinary Portland cement (OPC).
• “First few months” indicates beyond 28 days, up to about 90 days.
• Standard curing conditions are implied.

Concept / Approach:
Portland blast furnace slag cement (PBFS/PBFSC) contains latent hydraulic slag. Early strength gain (1–28 days) is typically slower than OPC, but slag reacts progressively to form additional hydrates, resulting in comparable or superior strengths at 90 days and beyond. PPC (pozzolana) shows a similar but often less pronounced trend; however, the classic statement associating “first three months lower, afterwards equal” is most consistently attributed to slag cement in many standard texts.

Step-by-Step Solution:
Identify which cement has slower early kinetics but strong later gain → slag cement.Eliminate rapid-hardening cement: it has faster early strength than OPC.Low-heat cement slows early heat and strength and may remain lower longer; the standard equivalence at later ages is more typical of slag cement.

Verification / Alternative check:
Performance curves in materials handbooks show PBFSC approaching/equaling OPC by 90 days, with added benefits of reduced permeability and better sulphate resistance.

Why Other Options Are Wrong:

• Rapid-hardening cement: opposite trend (higher early strength).
• Low-heat cement: designed to limit heat evolution; long-term parity is not the textbook emphasis.
• PPC: also slower early, but the canonical “after three months equal” phrasing is most closely tied to slag cement in many exam contexts.

Common Pitfalls:
Assuming all blended cements behave identically; mix design, slag/pozzolana content, and curing significantly influence the curves.

Final Answer:
Portland blast furnace slag cement