Tang Luping

CHLORIDE BINDING CAPACITY AND BINDING ISOTHERMS OF OPC PASTES AND MORTARS

A method for evaluating chloride binding capacity of concrete was proposed based on the adsorption from solution and chloride binding isotherms of OPC pastes and mortars with water-cement ratio 0.4, 0.6 and 0.8. The experimental results show that the chloride binding capacity of concrete strongly depends on the content of CSH gel in the concrete, regardless of the water-cement radio and the addition of aggregate. The relationship between the bound chloride and the free chloride can be described by Freundlich isotherm at high free chloride concentrations and Langmuir isotherm at low free chloride concentrations. (11 refs.)

A study of the quantitative relationship between strength and pore-size distribution of porous materials

Abstract A porous material is assumed to be made up of many porous bodies which contain various size pores and are parallelly connected. The quantitative relationship between strength and pore-size distribution of porous materials was derived based on the Griffiths theory and the theory of composite, and the block diagram of computer program used to treat this relationship was also put out. Various cement mortar samples and line-sand silicate concrete samples were tested by using the model of cylindrical pores crossed perpendicularly in three-dimensional space, same as the model in mercury porosimetry. The results show that there is much correspondence between the actual strength and the strength calculated based on the relationship derived in this paper.

A STUDY OF THE QUANTITATIVE RELATIONSHIP BETWEEN PERMEABILITY AND PORE SIZE DISTRIBUTION OF HARDENED CEMENT PASTES

The fluid flow through hardened cement paste was theoretically analyzed by introducing the conception of long-range force and the quantitative relationship between permeability and pore size distribution was derived based on the model of intercepting cylindrical pores and the model of parallel porous bodies. Thirteen sets of data of various hardened cement pastes reported by other researchers were used to verify the derived relationship. The result show a good correspondence between the calculated permeability and the experimental permeability and the regressive square correlative coefficient is up to 0.97. The definition of impermeability coefficient was proposed and the difference between water and gas permeabilities was discussed. The derived relationship gives a better explanation to this difference. It might be accurate and convenient enough to evaluate or predict the impermeability of hardened cement paste by using the impermeability coefficient proposed in this paper instead of time consumptive and labour intensive permeability experiment.