After actual fires with plastic materials involved concrete surfaces are often infested with high chloride concentrations, causing a serious risk of corrosion of the reinforcement. Absorption techniques with lime paste have been recommended to remove chlorides from concrete surfaces. To study this reaction concrete beams with different chloride contents, added as sodium chloride, were cast. The chloride distribution in the concrete before and after lime paste treatment and the chloride content of the used lime were determined analytically. The results show that the lime does not absorb chlorides, and within the concrete, the chlorides are redistributed. Further tests were made to study the rate of chloride absorption from aqueous solutions by lime, acti-vated carbon and ion exchange resins. The amount of absorbed chloride was very low. Corresponding the absorption of chlorides by fresh pastes of different cements and completely hydrated cements was studied. An effect of absorption but much more of chemical bond was shown.

A study was carried out to assess the residual strength of reinforced concrete columns after exposure to a standard fire for various lengths of time, and cooling. The use of a mathematical model, an ultrasonic pulse test method and a load test method are investigated. Calculated temperatures and residual strengths of test columns were compared with those measured. Comparisons were also made between calculated and measured pulse velocities. The results indicated that using the calculation procedure and the method of measuring pulse velocity described in the study, the residual strength of concrete columns can be assessed with an accuracy sufficient for practical purposes.

Experiments were carried out ith measurements of the total defo ission in order to investigate the evelopment and deformation behavio y temperature conditions.S purpose specimens were loaded wi th different stress le- on normal concrete specirmation and of the acou-correlation between ur of concrete during vels and heated up to maximum temperatures between 150 "C and 750 OC. After a holding period the specimens were cooled under load. The creep deformations showed strongly increasing rates at about 450 OC during heating and at the beginning of the cooling phase. , In the heating phase the activity of acoustic emissions increased considerably. During the holding period no remarkable activity e observed. A new increase of the acoustic activity could rly observed at the beginning of the cooling phase. rmal concrete specimen, the main a.ctivity in the damaging occurs during unsteady temperature conditions, and is nt on the maximum temperature reac hed. parison between acoustic emission activity and creep de-formations shows that the acoustic emission activities are high at e time that creep deformations areI high.

Generalised response curves for the transient thermal strain behaviour of concrete have been developed from a series of tests employing a wide range of materials and a lower than normal heating , rate. The latter allowed detailed assessment of underlying "material" behaviour to be made which was not complicated by "structural" effects that develop at a fast heating rate. The temperature, stress and moisture conditions within a cylindrical test specimen have been investigated and a study of the behaviour of individual constituents has confirmed that aggregate thermal stability is a critical factor. Thermal strains during virgin heating were separated into "Free" and "Load Induced" components possessing different and distinct properties allowing successful prediction of residual strains. A master with te m first h analysis the mast While t effect 0 clearly sensitiv thermal curve connecting Load Induced perature up to 450°C was found eating for different concretes of heated concrete structures er curve signified onset of c ransient creep did not occur duringf cracking caused bv thermal inc evident. Strain measurements, the indicators cycle. of damage taking Thermal Strain to exist during thus simplifying Departure from concrete damage. ing cooling, the ompatibility was harefore, proved place during the

SP92 This publication is a compilation of 11 papers dealing exclusively with the analysis and repairability of concrete damaged in building fires. Due to the importance of concrete and its role in the structural performance of modern buildings, the ability to deal with fire-damaged concrete is a central issue. This symposium volume combines the knowledge and experience of fire safety experts from around the world. The topics covered include the following: experience of fires in concrete structures; fires during nuclear power plant construction; assessment and repair of fire-damaged concrete; residual properties of concrete heated rapidly; and residual strength of fire-exposed reinforced concrete columns. Evaluation and Repair of Fire Damage to Concrete will give the reader substantial insight into both the problems and solutions associated with concrete which has been exposed to high temperatures.