CITY PROJECT - 1821 & 1823 E Chestnut Ave - Plan

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ASSOCIATED SOILS ENGINEERING, INC. Project No.: 7160.23 2860 Walnut Avenue, Signal Hill CA 90755 January 23, 2024 Tel: (562) 426 -7990 * Fax: (562) 426 -1842 Page 25 5.8.1 Concrete Corrosion: Disintegration of concrete may be attributed to the chemical reaction of soils sulfates and hydrated lime and calcium aluminate with the cement. The severity of the reaction resulting in expansion and disruption of the cement is primarily a function of the concentration of soluble sulfates and the water-cement ratio of the concrete. A soluble sulfate content of 0.002% by weight has been recorded from testing per California Test Method (CTM) 417 conducted on on-site soils, as indicated in Appendix A. As per Table 19.3.1.1 of ACI 318-19, soils exhibiting soluble content less than 0.1% by weight are classified as having “S0” sulfate exposure category. As such, for structural features to be in direct contact with on-site soils, the special geotechnical requirements on the type of Portland cement or water cement ratio corresponding to the tested “S0” sulfate exposure category as per stipulated in Table 19.3.2.1 of ACI 318-19 should be considered. 5.8.2 Metal Corrosion: In the evaluation of soil corrosivity to metal, the hydrogen ion concentrates (pH) and the electrical resistivity of the site and backfill soils are the principal variables in determining the service life of ferrous metal conduit. The pH of soil and water is a measure of acidity or alkalinity, while the resistivity is a measure of the soils resistance to the flow of electrical current. Currently available design charts indicate that corrosion rates decrease with increasing resistivities and increasing alkalinities. It can also be noted that for alkaline soils, the corrosion rate is more influenced by resistivity than by pH. The resistivity value of 1,953 ohm-cm per ASTM G187-23 Test Method coupled with a pH-value of 8.22 per CTM 643 classifies the on-site soils tested to be “Corrosive” to buried ferrous metals. Based on CTM 643, the year to perforation for 18-gauge steel in contact with soils of similar resistivity and pH-value is approximately 32 years for the “Corrosive” on-site soils. In lieu of additional testing, alternative piping materials, i.e. plastic piping, may be used instead of metal if longer service life is desired or required for utility pipes and fittings in direct contact with on-site soils. These resistivity values of on-site soils may also have implications to other building materials and depths of embedment for steel reinforcement, etc. It is recommended that a qualified corrosion consultant be engaged to review the building plans. A soluble chloride content of 14 ppm was recorded in our laboratory tests per CTM 422. Per Caltrans guidelines and specifications (References 21 and 22), soils exhibiting soluble chloride contents exceeding 500 ppm are considered “corrosive”. The soils are thus classified as “non- corrosive” per Caltrans criterion. In addition, special measure in terms of rebar protection against