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Compressive strength prediction of Portland cement concrete with age using a new model. Abstract. Based on the existing experimental data for compressive strength values of different concrete mixes, a statistical analysis for the gathered data was conducted.
The analysis revealed a model for predicting the compressive strength of concrete mixes at any age with the help of two constants (A) and (B) that are considered as a characteristic property for a concrete mix. The constant (A) is introduced as a rate of strength gain constant whereas, (B) is introduced as grade of strength constant. Once the values of constants (A) and (B) are defined for a concrete mix, the compressive strength at any age could be simply predicted without collecting data at that age. Keylogger Refog Download. The values of (A) and (B) could be determined by one of two methods. Solving two simultaneous equations at two different ages while performing either design or trial concrete mix is a method that could be used to define the two constants.
Other method is based on concrete strength at 2. The proposed model was studied for different concrete mixes. The study covered some parameters including the influence of, mineral admixtures as a partial replacement of cement, metakaolin, nano silica fume, curing in water or lime and the effect of curing temperature. The analysis reveals that mixes containing no admixtures, mixes containing silica fume and cured at normal temperature, mixes containing nano silica and cured in water are following with high accuracy the proposed model.
Keywords. Concrete; Compressive strength; Prediction; Hydration degree. Introduction. Compressive strength of concrete is one of the most important and useful properties. As a construction material, concrete is employed to resist compressive stresses. While, at locations where tensile strength or shear strength is of primary importance, the compressive strength is used to estimate the required property. Common trend in concrete technology is to use compressive strength as a quantitative measure for other properties of hardened concrete . CSH is the compound resulting from hydration and it gives concrete its strength. Cement based materials develop strength with continued hydration.
The rate of gain of strength is faster at start and the rate gets reduced with age . In spite of considering the 2. Most codes of practice do not consider the increase of strength beyond 2. Many research workers have attempted to estimate the strength of concrete at 1, 3 or 7 days and correlate to 2. Numerous research works have provided certain relationships.
For instance; In Germany, the relation between 2. K1 and K2 are the coefficients which are varied for different cements and curing conditions. The value of K1 ranges from 0. K2 from 3 to 6 . Whereas, for rapid strength Portland cement concrete those values were given as 0. But with issuing the last version of ECP . Abrams suggested a mathematical relationship between concrete strength and water/cement ratio as: where (fc) is the compressive strength of concrete; A and B are experimental parameters for a given age, material and curing conditions; and (x) is water/cement ratio by mass. For an average Portland cement concrete cured under normal temperature and moisture, Abrams gave the relationship between compressive strength and water/cement ratio as .
Moreover (x) is the water/cement ratio. To consider the use of mineral admixtures in concrete, many studies have shown that when the water/binder ratio is used instead of water/cement ratio as basis for mix design; strength prediction becomes more accurate.