A Proposal of Temperature-Time Function on the Strength Development of Concrete Under Sub-Zero Temperature

Abstract

Compressive strength development of concrete is essential for cold weather concreting. It is well known that strength development of concrete under the freezing point is much delayed. But the evaluation method has not been shown clearly yet. Therefore when average outside air temperature is under the freezing point planning method of cold weather concreting is not clear. We focus on the concept of equivalent maturity method proposed by Sudo, attempted to propose a time-temperature function representing the strength development of concrete under sub-zero temperature. As a result, we have proposed a function to calculate the maturity under sub-zero temperature. The proposed function could explain the strength development of the concrete exposure in winter.

Influence of Pre-Curing Period at Sub-Zero Temperature （-20℃） on the Compressive Strength of Concrete

“…The freezing temperature of Group 1 has remarkably pressive strength curve for Group 2. The accumulated temperatures were calculated using Equation ［1］ and Equation ［2］ according to AIJ guideline 11,12) . All curves show same tendency regardless of the pre-curing period.…”

Maturity and Strength Development of Mortar with Antifreezing Admixture at Temperatures Lower than 0 °C

“…It is generally acceptable to compute the maturity with Equation (1) for predicting the strength development of concrete. The maturity equation applicable at temperatures lower than 0 °C, as proposed in previous studies, is given in Equation (2) [5,11]. Case of T ≧ 0 M = ∑( T + 10) Δt Case of T < 0 M = ∑10 × exp(−0.60 × (− T ) 0.74 ) Δt where M denotes the maturity (°D·D), T the temperature (°C), and Δt the time interval (days).…”

“…The equivalent age, which is a temperature–time function obtained using Equation (5), can be expressed as follows in terms of the reaction rate integer k T and the reference temperature K rf [11]. t e = ∑( k T /k rf )· Δt = −(exp((∑ E + αμ / RT ) − (− E / RT rf )))· Δt where t e denotes the equivalent age (days), K rf the reaction rate integer at the reference temperature T rf (K) , and Δt the time interval.…”

“…Here, based on Equation (2), which gives the temperature–time function in the absence of the antifreezing admixture [5,11], a temperature–time function that can be expressed with variables such as temperature and addition of the antifreezing admixture is regarded as a logarithmic value of the equivalent age, as given below: ln ( t e ) = (−0.60 + βx ) × (− T c − ex ) (0.74 + γx ) where T c denotes temperature (°C); β , γ , and e are experiment integers; and x denotes the quantity of the antifreezing admixture (ℓ) added per 100 kg of cement.…”

“…Generally, a maturity is used to estimate the strength of concrete in cold-weather construction [5,9,10,11]. A maturity equation for estimating the strength of concrete at temperatures lower than 0 °C has been proposed in the literature [5,11]. However, this empirical equation is limited to ordinary Portland cement (OPC) and fly ash cement Type B (FB).…”