Twenty (20) different local and imported tiles were sampled from major hardware's in Bungoma. The samples collected were separately ground, sieved, through a 0.5mm mesh, dried at 110° C, weight and packed in a 200ml stoppered plastic bottles. The samples were stamped with identification numbers and kept for 30 days for secular equilibrium to be reached between the activity of 238 U, 232 Th , 40 K radium and their progeny. The average activity concentration of 238 U, 232 Th and 40 K was found to be 109±5.48Bqkg -1 , 11±0.55 Bqkg -1 and 1574±78.7 Bqkg -1 respectively. The average absorbed dose rate was found to be 140±7.03 nGyh -1 which is higher than the worlds average value of 60 nGyh -1 . The average radium equivalent was found to be 288±14.44 Bqkg -1 which is lower than the world limit value of 370Bqkg -1 . External and internal hazard indices were found to be 0.70±0.03 msvy -1 and 0.80±0.04 msvy -1 respectively. Therefore, the sampled tiles used in Bungoma county for construction has minimal radiological threat to population.

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Samples of sand were collected along the course of ten selected rivers two from each river through random sampling. Activity concentration of 238 U, 232 Th and 40 K were measured using high resolution NaI(Ti) gamma ray spectrometer. Activity concentration of the three primordial radionuclides obtained were used to calculate, absorbed dose rate, annual effective dose rate, interna and external hazard indices and radium equivalent. The average activity concentration for the three primordial radioactive nuclides were; 2±0.1Bq/kg with a range of 0± 0.03Bq/kg to 4±0.24Bq/kg for 238 U, 55±2.78Bq/kg with a minimum value of 32±1.6Bq/kg and a maximum value of 87±4.38Bq/kg for 232 Th and 51±2,56Bq/kg with a minimum value of 27±1.37Bq/kg and a maximum value of 76±3.8Bq/kg for 40 K. The mean activity concentrations for 238 U and 40 K were below the world averages of 33Bq/kg and 420Bq/kg respectively. The indoor and outdoor annual effective dose rate varied from 0±0mSv/y to 0.2±0.01mSv/y with an average of 0.1±0 mSv/y and 0±0.003mSv/y to 0.1±0.009mSv/y with a mean of 0.1±0.006 mSv/y respectively. The annual effective dose rates were below the safe limits of 1mSv/y. Therefore, use of sand from the selected rivers in Bungoma County, Kenya for construction has minimal health risks to the inhabitants.

Concrete is among the foremost used construction materials around the world, however, there is limited information to determine how aging concrete is affected by chemicals. Concrete is used in the construction of domestic and industrial infrastructure including walls, beams, roof slabs, pipes and drainage systems. With increasing industrialization, chemicals are continuously released contributing to concrete degradation. Sulfuric acid is one of the most detrimental chemicals to concrete, yet it is commonly used in most industries. The effects of carbon dioxide, alum, and soda ash on 40–50 year old concrete structures were determined. Results showed the presence of Fe3+ ions with a mean concentration of 3.24 ± 0.02 mg/L in the residuum on the alum tank. This was due to the slightly acidic alum solution reacting with calcium hydroxide and iron in the concrete matrix over years thus depriving concrete of its binding power. The high amount of soda ash, a strong base, corrodes the concrete walls and surfaces hence creating cracks on the concrete matrix. Carbonation effects brought about by carbon dioxide were also observed at the time of the study.

Superabsorbent hydrogels continue to be very important materials due to their applications in several technologies. Unfortunately, most superabsorbent hydrogels currently on the market are acrylate-based products that are non-biodegradable, and, most importantly, some concerns exist about their toxicity for use in agriculture. This study aimed at synthesizing and characterizing biocompatible superabsorbent hydrogel derived from lemon juice. The process involved polymerizing lemon juice (LJ) with glycerol (G) monomers to form polymeric material (HLG-1). HLG-1 was then converted to HLG-2 by crosslinking with maleic acid. Characterization of the hydrogels was done using Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscope (SEM), and X-ray diffraction (XRD). The synthesis conditions producing optimal swelling capacity were studied by varying contact time and dosage of both lemon juice and the cross-linker. The FT-IR results showed a peak at 1528 cm-1 and 1591.34 cm-1 associated with –COO- stretching indicating successful polymerization and crosslinking processes. XRD analysis showed conversion from amorphous to crystalline phases upon crosslinking. SEM micrographs showed clear pores with large surface area in HLG-2 compared with the rigid and constricted surface of HLG-1 hydrogel. A maximum swelling capacity of 910% was obtained upon synthesizing hydrogel HLG-2 with lemon juice, glycerol, and maleic acid of a volume ratio of 5.4: 3.75: 3.75 respectively. Crosslinking the hydrogel with maleic acid was found to improve the water absorption capacity of the hydrogel. The superabsorbent hydrogel with such high swelling and water absorption ability has the potential of being applied in arid and semi-arid regions to boost agricultural production.