Hydration is a main process following mixing of cement with water, producing a chemical reaction between cement particles and water molecules known as Calcium-Silica-Hydroxide (C-S-H). The C-S-H acts as a binder between coarse and fine mix aggregates. During mixing, capillary voids are formed where water can easily become trapped. The van der Waals force being the principal source of strength between such compounds, voids become detrimental to long-term strength of concrete because they decrease the amount of surface area aggregate and cement particles have to come into contact with each other. An overall decrease in both pores size and their distribution in concrete increase density, therefore increasing the van der Waals force between these particles. In order to reduce capillary pores size and their distribution, in this paper we present a result from preliminary investigation on how gamma ray exposure during the early stages of the curing process affect the concrete mixture strength values. The gamma ray enhanced curing is expected to break the water molecules trapped in capillary pores into H+ and OH−, allowing these ions to escape and therefore result in densifying the concrete mixture.
Concrete cubes of 5cm3 in volumes are exposed to isotropic 137Cs gamma emitting source. The absorbed dose in cubes is measured as well as calculated using MCNP6. Each concrete cube is exposed to a 630 MBq 137Cs source for seven continuous days. The absorbed dose is experimentally measured using a Landauer nanoDot system. The average measured dose is 1.12 Gy at the front and 0.33 at the back of a concrete, totaling 0.79 Gy. The average measured dose is 0.98 Gy at the front and 0.29 Gy at the back, totaling 0.69 Gy of absorbed dose, thus showing a good agreement between the numerical predictions and experimental measurements.
Compressive strength of concrete mixes exposed to gamma rays during the curing time and those cured without exposure to gamma radiation are tested. Preliminary data shows that the average compressive strength for gamma ray enhanced curing of concrete mixes is in order of 9,000 psi while the average com-pressive strength for the cubes cured in dry air is on average about 5,000 psi. A number of new experiments is planed until the time of the Conference in providing more exact answer to the question: does gamma ray enhanced curing of concrete increase its strength and reduces the curing time?